FindLaw - 600 Technology Square (Cambridge, MA) Lease - Technology Square LLC and Akamai Technologies Inc.
                               EXHIBIT 1, SHEET 1
                                Building No. 600
                                TECHNOLOGY SQUARE
                         Cambridge, Massachusetts 02139

                                   LEASE DATA

Execution Date:     NOVEMBER 28, 2000

Tenant:             AKAMAI TECHNOLOGIES, INC.
                    a Delaware corporation

Mailing Address:    Akamai Technologies, Inc.
                    500 Technology Square
                    Cambridge, Massachusetts 02139-3539

Landlord:           TECHNOLOGY SQUARE LLC, a Delaware limited liability company
                    (the sole manager of which is Beacon Capital Partners L.P.,
                    a Delaware limited partnership d/b/a Beacon Capital Partners
                    Limited Partnership; the sole general partner of which is
                    Beacon Capital Partners, Inc., a Maryland corporation)

Mailing Address:    c/o Beacon Capital Partners, One Federal Street, Boston,
                    Massachusetts 02110, Attention: General Counsel

Complex:            The land, buildings and other improvements thereon, from
                    time to time, located off Main Street in the City of
                    Cambridge, Middlesex County, Commonwealth of Massachusetts
                    known as Technology Square. The Complex is initially
                    substantially as shown on Exhibit 6, Sheet 1, and the legal
                    description of the Complex is set forth on Exhibit 6, Sheets
                    2, 3, and 4; however, the Complex may change from time to
                    time as set forth herein. Without limiting the foregoing,
                    the parties acknowledge that the Complex presently consists
                    of Buildings 200, 400 and 500. The parties anticipate that
                    Building 300 will be added to the Complex in May 2001;
                    Building 600 will be added to the Complex on or before the
                    Full Rent Commencement Date and Building 700 will be added
                    to the Complex one month after Building 600. There is no
                    current estimate of when Building 100 will be added to the
                    Complex.

Building:           600 Technology Square, Cambridge, Massachusetts

Premises:           A PORTION OF THE FIRST (1ST) AND THE ENTIRETY OF THE
                    SECOND (2ND), THIRD (3RD), FOURTH (4TH) AND FIFTH
                    (5TH) FLOORS OF THE BUILDING, SUBSTANTIALLY AS SHOWN
                    ON LEASE PLAN, EXHIBIT 2, SHEETS 1, 2, 3, 4 AND 5.

Art. 3.1            Specified Commencement Date:         May 1, 2001

<PAGE>   2

                               EXHIBIT 1, SHEET 2
                                Building No. 600
                                TECHNOLOGY SQUARE
                         Cambridge, Massachusetts 02139

                        Tenant: AKAMAI TECHNOLOGIES, INC.
                        Execution Date: NOVEMBER 28, 2000


                    Term Commencement Date: Substantial Completion Date

                    Estimated Full Rent Commencement Date:      October 1, 2001

Art. 3.2            Termination Date:  TWELVE (12) YEARS AFTER THE FULL RENT
                                       COMMENCEMENT DATE

Art. 4.3            Landlord's Construction Representative: Greg Walsh

                    Tenant's Construction Representative: Skip Hartwell

Art. 5              Use of Premises: GENERAL BUSINESS OFFICE USE

Art. 6              Yearly Rent:

                    RENT YEAR            YEARLY RENT      MONTHLY PAYMENT

                     1 - 6:(1)          $6,818,760.00      $568,230.00

                      7-12:             $7,386,990.00      $615,582.50

Art. 7              Total Rentable Area of the Premises:    113,646 square feet

                    Total Rentable Area of the Building:    127,150 square feet

                    Total Rentable Non-Retail Area of
                        the Building                        113,646 square feet

                    Initial Total Rentable Area of the Complex:

                    Buildings 200, 400 and 500              532,279 square feet
                    Building 300                            175,226 square feet
                    Building 600                            127,150 square feet

----------------------------
(1) For the purposes of this Lease, "Rent Year 1" shall be defined as the
twelve-(12)-month period commencing as of the Rent Commencement Date and ending
on the last day of the month in which the first (1st) anniversary of the Rent
Commencement Date occurs. Thereafter, "Rent Year" shall be defined as any twelve
(12) month period during the term of the Lease commencing as of the first (1st)
day of the month following the month in which any anniversary of the Rent
Commencement Date occurs.

                                       -2-
<PAGE>   3

                               EXHIBIT 1, SHEET 3
                                Building No. 600
                                TECHNOLOGY SQUARE
                         Cambridge, Massachusetts 02139

                        Tenant: AKAMAI TECHNOLOGIES, INC.
                        Execution Date: NOVEMBER 28, 2000

                    Building 700                             49,508 square feet

Art. 8              Electricity:     Electric current will be metered and paid
                                     for by Tenant in accordance with Article
                                     8.1 of the Lease.

Art. 9              Operating and Tax Escalation:

                         Operating Cost Base: $681,876.00 (i.e. $6.00 per square
                                              foot of Total Rentable Area of the
                                              Non-Retail Area of the Building)

                         Tax Base:            $397,761.00 (i.e. $3.50 per square
                                              foot of the Total Rentable Area of
                                              the Premises)

                         Tenant's Building Operating Cost Percentage:  100%

                         Tenant's Building Tax Percentage: 89.38%

                         Tenant's Complex Tax Percentage: The Total Rentable
                         Area of the Premises divided by the Total Rentable Area
                         of the Complex, as the same may change from time to
                         time.

Art. 29.3           Co-Brokers:    INSIGNIA/ESG AND SPAULDING & SLYE

Art. 29.5           Arbitration:   SUPERIOR COURT; MIDDLESEX COUNTY

                    Exhibit Date:  LEASE PLAN, EXHIBIT 2, SHEETS 1, 2, 3, 4 AND
                                   5 DATED NOVEMBER 28, 2000

                                      -3-
<PAGE>   4

                               EXHIBIT 1, SHEET 4
                                Building No. 600
                                TECHNOLOGY SQUARE
                         Cambridge, Massachusetts 02139

                        Tenant: AKAMAI TECHNOLOGIES, INC.
                        Execution Date: NOVEMBER 28, 2000

LANDLORD:                               TENANT:

TECHNOLOGY SQUARE LLC,                  AKAMAI TECHNOLOGIES, INC.
a Delaware limited liability company    a Delaware corporation

By: Beacon Capital Partners L.P.,
    a Delaware limited partnership
    d/b/a Beacon Capital Partners
    Limited Partnership, its manager

    By: Beacon Capital Partners, Inc., a
        Maryland corporation, its general
        partner

        By: /s/ Thomas Ragno            By: /s/ Kathryn L. Jorden
            -----------------------         ----------------------------
        Name: Thomas Ragno              Name: /s/ Kathryn L. Jorden
                                              --------------------------
        Title: Senior Vice President    Title: VP, General Counsel
                                               -------------------------
Date Signed: 12/05/00                   Date Signed: 12/05/00
             ----------------------                  -------------------


                                      -4-
<PAGE>   5

                                TABLE OF CONTENTS



<TABLE>
<S>                                                                          <C>
1.       REFERENCE DATA                                                       1


2.       DESCRIPTION OF DEMISED PREMISES                                      1
         2.1      DEMISED PREMISES............................................1
         2.2      APPURTENANT RIGHTS..........................................1
         2.3      PARKING.....................................................1
         2.4      EXCLUSIONS AND RESERVATIONS.................................2


3.       TERM OF LEASE                                                        2
         3.1      DEFINITIONS.................................................2
         3.2      HABENDUM....................................................3
         3.3      DECLARATION FIXING TERM COMMENCEMENT DATE...................3


4.       CONSTRUCTION                                                         3
         4.0      LANDLORD'S WORK.............................................3
         4.1      TENANT'S REMEDIES BASED ON DELAYS IN LANDLORD'S WORK........9
         4.2      TENANT'S WORK..............................................11
         4.3      QUALITY AND PERFORMANCE OF WORK............................13


5.       USE OF PREMISES                                                     13
         5.1      PERMITTED USE..............................................13
         5.2      PROHIBITED USES............................................14
         5.3      LICENSES AND PERMITS.......................................14


6.       RENT AND SPECIAL ALLOWANCE                                          14
         6.1.     RENT.......................................................14
         6.2      LANDLORD'S CONTRIBUTION....................................15


7.       RENTABLE AREA                                                       17


8.       SERVICES FURNISHED BY LANDLORD                                      17
         8.1      ELECTRIC CURRENT...........................................17
         8.2      WATER......................................................18
         8.3      ELEVATORS, HEAT, CLEANING..................................18
         8.4      AIR CONDITIONING...........................................19
         8.5      ADDITIONAL HEAT, CLEANING AND AIR CONDITIONING SERVICES....19
         8.6      ADDITIONAL AIR CONDITIONING EQUIPMENT......................19
         8.7      REPAIRS....................................................20
         8.8      INTERRUPTION OF CURTAILMENT OF SERVICES....................20
</TABLE>

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<PAGE>   6

<TABLE>
<S>                                                                          <C>
         8.9      ENERGY CONSERVATION........................................21
         8.10     MISCELLANEOUS..............................................21


9.       ESCALATION                                                          21
         9.1      DEFINITIONS................................................21
         9.2      TAX EXCESS.................................................29
         9.3      OPERATING EXPENSE EXCESS...................................30
         9.4      PART YEARS.................................................30
         9.5      EFFECT OF TAKING...........................................30
         9.6      ADJUSTMENT OF OPERATING COSTS BASED UPON OCCUPANCY.........31
         9.7      EFFECT OF CONVERSION OF COMPLEX TO A CONDOMINIUM...........31
         9.8      DISPUTES, ETC..............................................31
         9.9      TENANT'S AUDIT RIGHTS......................................31


10.      CHANGES OR ALTERATIONS BY LANDLORD                                  35


11.      FIXTURES, EQUIPMENT AND IMPROVEMENTS--REMOVAL BY TENANT             35


12.      ALTERATIONS AND IMPROVEMENTS BY TENANT                              36


13.      TENANT'S CONTRACTORS--MECHANICS' AND OTHER LIENS--
         STANDARD OF TENANT'S PERFORMANCE--COMPLIANCE WITH LAWS              37


14.      REPAIRS BY TENANT--FLOOR LOAD                                       39
         14.1     REPAIRS BY TENANT..........................................39
         14.2     FLOOR LOAD--HEAVY MACHINERY................................39


15.      INSURANCE, INDEMNIFICATION, EXONERATION AND EXCULPATION             39
         15.1     GENERAL LIABILITY INSURANCE................................39
         15.2     CERTIFICATES OF INSURANCE..................................40
         15.3     GENERAL....................................................40
         15.4     PROPERTY OF TENANT.........................................41
         15.5     BURSTING OF PIPES, ETC.....................................41
         15.6     REPAIRS AND ALTERATIONS--NO DIMINUTION OF RENTAL VALUE.....42


16.      ASSIGNMENT, MORTGAGING AND SUBLETTING                               42


17.      MISCELLANEOUS COVENANTS                                             46
         17.1     RULES AND REGULATIONS......................................46
         17.2     ACCESS TO PREMISES--SHORING................................47
         17.3     ACCIDENTS TO SANITARY AND OTHER SYSTEMS....................47
</TABLE>

                                      -ii-
<PAGE>   7

<TABLE>
<S>                                                                          <C>
         17.4     SIGNS, BLINDS AND DRAPES...................................48
         17.5     ESTOPPEL CERTIFICATE.......................................49
         17.6     PROHIBITED MATERIALS AND PROPERTY..........................49
         17.7     REQUIREMENTS OF LAW--FINES AND PENALTIES...................49
         17.8     TENANT'S ACTS--EFFECT ON INSURANCE.........................50
         17.9     MISCELLANEOUS..............................................50


18.      DAMAGE BY FIRE, ETC.                                                50


19.      WAIVER OF SUBROGATION                                               53


20.      CONDEMNATION - EMINENT DOMAIN                                       53


21.      DEFAULT                                                             55
         21.1     CONDITIONS OF LIMITATION - RE-ENTRY - TERMINATION..........55
         21.2     INTENTIONALLY OMITTED......................................56
         21.3     DAMAGES - TERMINATION......................................56
         21.4     FEES AND EXPENSES..........................................57
         21.5     WAIVER OF REDEMPTION.......................................57
         21.6     LANDLORD'S REMEDIES NOT EXCLUSIVE..........................58
         21.7     GRACE PERIOD...............................................58


22.      END OF TERM - ABANDONED PROPERTY                                    58


23.      SUBORDINATION                                                       59


24.      QUIET ENJOYMENT                                                     61


25.      ENTIRE AGREEMENT -- WAIVER -- SURRENDER                             62
         25.1     ENTIRE AGREEMENT...........................................62
         25.2     WAIVER.....................................................62
         25.3     SURRENDER..................................................62


26.      INABILITY TO PERFORM - EXCULPATORY CLAUSE                           63


27.      BILLS AND NOTICES                                                   63


28.      PARTIES BOUND -- SEIZIN OF TITLE                                    64
</TABLE>

                                     -iii-
<PAGE>   8

<TABLE>
<S>                                                                          <C>
29.      MISCELLANEOUS                                                       64
         29.1     SEPARABILITY...............................................64
         29.2     CAPTIONS, ETC..............................................64
         29.3     BROKER.....................................................65
         29.4     MODIFICATIONS..............................................65
         29.5     ARBITRATION................................................65
         29.6     GOVERNING LAW..............................................66
         29.7     ASSIGNMENT OF RENTS........................................66
         29.8     REPRESENTATION OF AUTHORITY................................66
         29.9     EXPENSES INCURRED BY LANDLORD UPON TENANT REQUESTS.........66
         29.10    RETAIL AREA................................................67
         29.11    SURVIVAL...................................................67


EXHIBIT 2  Lease Plan                                                        69


EXHIBIT 2-1  Plan of Complex                                                 70


EXHIBIT 3  Requirements for Tenant's Plans                                   71


EXHIBIT 4  Building Services                                                 72


EXHIBIT 5  Form of Letter of Credit                                          75


EXHIBIT 6  Base Building Specifications                                      77


EXHIBIT 7  Exterior Signage                                                  78


EXHIBIT 8  Tenant's Removable Property                                       79



RIDER TO LEASE                                                               80
</TABLE>

                                      -iv-
<PAGE>   9

     THIS INDENTURE OF LEASE made and entered into on the Execution Date as
stated in Exhibit 1 and between the Landlord and the Tenant named in Exhibit 1.

Landlord does hereby demise and lease to Tenant, and Tenant does hereby hire and
take from Landlord, the Premises hereinafter mentioned and described
(hereinafter referred to as "Premises"), upon and subject to the covenants,
agreements, terms, provisions and conditions of this Lease for the term
hereinafter stated:

1.   REFERENCE DATA

     Each reference in this Lease to any of the terms and titles contained in
any Exhibit attached to this Lease shall be deemed and construed to incorporate
the data stated under that term or title in such Exhibit.

2.   DESCRIPTION OF DEMISED PREMISES

     2.1  DEMISED PREMISES. The Premises are that portion of the Building as
described in Exhibit 1 and is hereinafter referred to as "Building",
substantially as shown hatched or outlined on the Lease Plan (Exhibit 2) hereto
attached and incorporated by reference as a part hereof.

     2.2  APPURTENANT RIGHTS. Tenant shall have, as appurtenant to the Premises,
rights to use in common, with others entitled thereto, subject to reasonable
rules from time to time made by Landlord of which Tenant is given notice; (a)
the common lobbies, hallways, stairways and elevators of the Building, serving
the Premises in common with others, (b) common walkways necessary for access to
the Building, and (c) if the Premises include less than the entire rentable area
of any floor, the common toilets and other common facilities of such floor; and
no other appurtenant rights or easements. Landlord shall allow Tenant's
telecommunication service provider to have access to the Building and to
Tenant's Premises, provided however, that Landlord shall have the right to
charge Tenant's provider fees in connection with the services being performed by
such provider. Notwithstanding the foregoing, so long as Tenant's
telecommunications service provider ("Provider") does not provide
telecommunications service to any other tenant of the Building, Landlord shall
not require such Provider to pay any fees for such access.

     2.3  PARKING. During the term of the Lease, commencing on the Rent
Commencement Date (and, if there is more than one Rent Commencement Date
pursuant to Article 3.1 hereof commencing on a pro rata basis with each such
Rent Commencement Date), the Landlord will make available, at Tenant's written
request, which request must be made on or before the Full Rent Commencement
Date, up to one and one-half (1.5) monthly parking passes per 1,000 square feet
of Total Rentable Area leased by Tenant (the "Parking Space Cap") for use in the
garage of the Complex or surface parking areas in the Building, as the same may
change from time to time ("Parking Areas"). If Tenant fails timely to make such
request for any such parking passes, Tenant shall have no right to obtain such
parking passes under this Article 2.3, except to the extent thereafter
available, as more specifically set forth herein. If Tenant requests fewer
passes than the Parking Space Cap prior to the Full Rent Commencement Date,
Tenant shall have the right, from time to time during the term of the Lease, to
request additional parking passes up to the Parking Space Cap. If Landlord has
such passes available, Landlord will provide the same to Tenant (but in no event
more than the Parking Space Cap), provided

                                      -1-
<PAGE>   10

however, that, if such passes are not available, Landlord shall have no
obligation to provide additional passes to Tenant. Tenant shall have no right to
sublet, assign, or otherwise transfer said parking passes, other than to an
Assignee or a Qualified Transferee pursuant to an approved assignment or
sublease under Article 16 of the Lease. Said parking passes shall be paid for by
Tenant at the then current prevailing rate in the Parking Areas, as such rate
may vary from time to time. If, for any reason, Tenant shall fail timely to pay
the charge for said parking passes, and if such default continues for ten (10)
days after written notice, Tenant shall have no further right to the parking
passes for which Tenant failed to pay the charge under this Article 2.3. Said
parking passes will be on an unassigned, non-reserved basis, and shall be
subject to such reasonable and uniform rules and regulations as may be in effect
for the use of said Parking Areas (including, without limitation, Landlord's
right, without additional charge to Tenant above the prevailing rate for parking
passes, to institute a valet or attendant-managed parking system), from time to
time in force.

     2.4  EXCLUSIONS AND RESERVATIONS. All the perimeter walls of the Premises
except the inner surfaces thereof, any balconies (except to the extent same are
shown as part of the Premises on the Lease Plan (Exhibit 2)), terraces or roofs
adjacent to the Premises, and any space in or adjacent to the Premises used for
shafts, stacks, pipes, conduits, wires and appurtenant fixtures, fan rooms,
ducts, electric or other utilities, sinks or other Building facilities, and the
use thereof, as well as the right of access through the Premises for the
purposes of operation, maintenance, decoration and repair, are expressly
excluded from the Premises and reserved to Landlord.

3.   TERM OF LEASE.

     3.1  DEFINITIONS. As used in this Lease the words and terms which follow
mean and include the following:

          (a)  "SPECIFIED COMMENCEMENT DATE" - The "Specified Commencement Date"
is the date (as stated in Exhibit 1) on which it is estimated that Landlord's
Work Necessary to Trigger Term Commencement Date will be substantially
completed.

          (b)  "TERM COMMENCEMENT DATE" - The "Term Commencement Date" is the
date on which the First Substantial Completion Date, as defined in Article
4.0(b), occurs.

          (c)  "RENT COMMENCEMENT DATE" - Subject to the provisions of this
Article 3.1(c), the "Rent Commencement Date" is the earlier of (i) the Outside
Rent Commencement Date, as defined in Article 3.1(d), or (ii) the date Tenant
takes possession of the whole of the Premises for use and operation of Tenant's
business as set forth in Exhibit 1. If Tenant takes earlier possession of any
portion of any floor on which the Premises are located prior to the Outside Rent
Commencement Date for use as set forth in Exhibit 1, then the Rent Commencement
Date for the entirety of the portion of the Premises located on such floor shall
occur as of the date that Tenant first takes such possession. As used herein,
the term "FULL RENT COMMENCEMENT DATE" shall mean the date on which the Rent
Commencement Date has occurred for the entirety of the Premises.

          (d)  "OUTSIDE RENT COMMENCEMENT DATE" - Subject to the provisions of
this Article 3.1(d), the "Outside Rent Commencement Date" shall be later of: (i)
one hundred fifty (150) days after the Term Commencement Date, or (ii) one
hundred twenty (120) days after

                                      -2-
<PAGE>   11

the Third and Fourth Floor Substantial Completion Date, as hereinafter defined,
or (iii) ninety (90) days after the First and Second Floor Substantial
Completion Date, as hereinafter defined, or (iv) sixty (60) days after the
Permanent Power Turn-On Date, as hereinafter defined, or (v) the Base Building
Substantial Completion Date, as hereinafter defined, or (vi) five (5) days after
the HVAC Operational Date, as hereinafter defined. Notwithstanding the
foregoing, if Tenant does not, in fact, substantially complete Tenant's Work
prior to the Outside Rent Commencement Date, as determined pursuant to the first
sentence of this Article 3.1(d), and if any Landlord Delays occur, then the
Outside Rent Commencement Date shall be extended by the number of days that any
Landlord Delay actually delays the substantial completion of Tenant's Work
beyond the Outside Rent Commencement Date, as determined pursuant to the first
sentence of this Article 3.1(d).

     3.2  HABENDUM. TO HAVE AND TO HOLD the Premises for a term of years
commencing on the Term Commencement Date and ending on the Termination Date as
stated in Exhibit 1 or on such earlier date upon which said term may expire or
be terminated pursuant to any of the conditions of limitation or other
provisions of this Lease or pursuant to law (which date for the termination of
the terms hereof will hereafter be called "Termination Date"). Notwithstanding
the foregoing, if the Termination Date as stated in Exhibit 1 shall fall on
other than the last day of a calendar month, said Termination Date shall be
deemed to be the last day of the calendar month in which said Termination Date
occurs.

     3.3  DECLARATION FIXING TERM COMMENCEMENT DATE, RENT COMMENCEMENT DATE, AND
TERMINATION DATE. As soon as may be after the execution date hereof, each of the
parties hereto agrees, upon demand of the other party to join in the execution,
in recordable form, of a statutory notice, memorandum, etc. of lease and/or
written declaration in which shall be stated the Term Commencement Date, the
Rent Commencement Date(s), and (if need be) the Termination Date. If this Lease
is terminated before the term expires, then upon Landlord's request the parties
shall execute, deliver and record an instrument acknowledging such fact and the
date of termination of this Lease, and Tenant hereby appoints Landlord its
attorney-in-fact in its name and behalf to execute such instrument if Tenant
shall fail to execute and deliver such instrument after Landlord's request
therefor within ten (10) days.

4.   CONSTRUCTION

     4.0  LANDLORD'S WORK.

     (a)  Landlord, at Landlord's sole cost and expense, shall perform the base
building work ("LANDLORD'S WORK") as defined in the Base Building Specifications
attached hereto as Exhibit 6. Landlord shall not make any material change in the
Base Building Specifications without obtaining the prior written approval of
Tenant (which approval shall not be unreasonably withheld, conditioned, or
delayed). Without limiting the foregoing, Landlord shall not make any material
changes in the finishes of the lobby of the Building without obtaining the prior
written approval of Tenant (which approval shall not be unreasonably withheld,
conditioned, or delayed). Notwithstanding the foregoing, Tenant hereby agrees
that: (i) with respect to the glasswall finish adjacent to the retail areas in
the lobby, Landlord may use an alternate wall finish in lieu of the materials
specified in the Base Building Specifications (which alternate finish shall be
at least equal in quality to the finishes contained in the lobby at 500
Technology Square as of the date hereof) and Landlord shall perform, as part of
the Landlord's Work, whatever sprinkler work is required by applicable codes in
connection with such wall finish, and

                                      -3-
<PAGE>   12

(ii) with respect to the lobby walls, Landlord may use an alternate finish in
lieu of the finish specified in the Base Building Specifications, provided that
such alternate finish is at least equal in quality to the finishes contained in
the lobby at 500 Technology Square as of the date hereof. Subject to delays due
to governmental regulation, unusual scarcity of or inability to obtain labor or
materials, labor difficulties, casualty or other causes reasonably beyond
Landlord's control (collectively "Landlord's Force Majeure"), Landlord shall use
reasonable speed and diligence in the construction of Landlord Work Necessary to
Trigger Term Commencement Date (as defined in Article 4.0(g) below) so as to
have the same substantially completed on or before the Specified Commencement
Date set forth in Exhibit 1, but Tenant shall have no claim against Landlord for
failure to complete construction of Landlord's Work, except as expressly set
forth in Article 4.1. In each such instance of Landlord's Force Majeure,
Landlord shall exercise reasonable diligence to eliminate the cause of such
inability to perform.

     (b)  The "FIRST SUBSTANTIAL COMPLETION DATE" shall be defined as the date
on which the Landlord's Work Necessary to Trigger Term Commencement Date, as
defined in Article 4.0(g), has been substantially completed, so that any
remaining Landlord's Work can be performed with a minimum of interference or
delay in the progress of Tenant's Work on the fifth floor, Tenant acknowledging,
however, the priority of Landlord's Work, as set forth in Article 4.2(c).

     (c)  The "THIRD AND FOURTH FLOOR SUBSTANTIAL COMPLETION DATE" shall be
defined as the date on which Landlord's Work Necessary to Trigger Third and
Fourth Floor Substantial Completion Date, as defined in Article 4.0(h), has been
substantially completed, so that any remaining Landlord's Work can be performed
with a minimum of interference or delay in the progress of Tenant's Work on the
third and fourth floors, Tenant acknowledging, however, the priority of
Landlord's Work, as set forth in Article 4.2(c). Notwithstanding the foregoing,
in the event of any Tenant Delays which actually delay the performance of
Landlord's Work Necessary to Trigger Third and Fourth Floor Substantial
Completion Date, the Third and Fourth Floor Substantial Completion Date shall be
defined as the date on which Landlord's Work Necessary to Trigger Third and
Fourth Floor Substantial Completion Date would have been substantially completed
but for such Tenant Delays.

     (d)  The "FIRST AND SECOND FLOOR SUBSTANTIAL COMPLETION DATE" shall be
defined as the date on which Landlord's Work Necessary to Trigger First and
Second Floor Substantial Completion Date, as defined in Article 4.0(i), has been
substantially completed, so that any remaining Landlord's Work can be performed
with a minimum of interference or delay in the progress of Tenant's Work on the
first and second floors, Tenant acknowledging, however, the priority of
Landlord's Work, as set forth in Article 4.2(c). Notwithstanding the foregoing,
in the event of any Tenant Delays which actually delay the performance of
Landlord's Work Necessary to Trigger First and Second Floor Substantial
Completion Date, the First and Second Floor Substantial Completion Date shall be
defined as the date on which Landlord's Work Necessary to Trigger First and
Second Floor Substantial Completion Date would have been substantially completed
but for such Tenant Delays.

     (e)  The "PERMANENT POWER TURN-ON DATE" shall be defined as the date on
which Landlord has made permanent electric power and the base building heating
and air conditioning system operational for the entire Premises, except that in
the event of any Tenant Delays which actually delay Landlord's ability to
achieve the Permanent Power Turn-On Date, the Permanent Power Turn-On Date shall
be defined as the date on which Landlord would have been able to

                                      -4-
<PAGE>   13

make permanent electric power and the base building heating and air conditioning
system operational for the entire Premises but for such Tenant Delays.

     (f)  The "BASE BUILDING SUBSTANTIAL COMPLETION DATE" shall be defined as
the date on which Landlord's Work Necessary to Trigger Rent Commencement Date,
as defined in Article 4.0(j), has been substantially completed, except that in
the event of any Tenant Delays which actually delay the performance of
Landlord's Work Necessary to Trigger Rent Commencement Date, the Base Building
Substantial Completion Date shall be defined as the date on which Landlord's
Work Necessary to Trigger Rent Commencement Date would have been substantially
completed but for such Tenant Delays.

     (g)  The "LANDLORD WORK NECESSARY TO TRIGGER TERM COMMENCEMENT DATE" shall
be defined as the following items of work:

          i.)       Site utilities serving the Building;
          ii.)      Foundation piles, grade beams, and structural slab on grade;
          iii.)     Under slab drainage and utilities;
          iv.)      Structural steel erected and set;
          v.)       Composite concrete decks;
          vi.)      Spray fireproofing;
          vii.)     Precast concrete Building exterior panels;
          viii.)    The fifth floor is Building Tight, as defined in Article
                    4.0(k), and
          ix.)      Any other portions of Landlord's Work necessary to enable
                    Tenant and its contractor to commence the Tenant's Work (as
                    defined in Article 4.2) on the fifth floor.

     (h)  The "LANDLORD WORK NECESSARY TO TRIGGER THIRD AND FOURTH FLOOR
SUBSTANTIAL COMPLETION DATE" shall be defined as the following items of work:

          i.)       The Landlord Work Necessary to Trigger Term Commencement
                    Date;
          ii)       Both the third and fourth floors are Building Tight, as
                    defined in Article 4.0(k); and
          iii)      Any other portions of Landlord's Work necessary to enable
                    Tenant and its contractor to commence the Tenant's Work on
                    both the third and fourth floors.

     (i)  The "LANDLORD WORK NECESSARY TO TRIGGER FIRST AND SECOND FLOOR
SUBSTANTIAL COMPLETION DATE" shall be defined as the following items of work:

          i.)       The Landlord Work Necessary to Trigger Term Commencement
                    Date;
          ii.)      The Landlord Work Necessary to Trigger Third and Fourth
                    Floor Substantial Completion Date;
          iii.)     Both the first and second floors are Building Tight, as
                    defined in Article 4.0(k); and
          iv.)      Any other portions of Landlord's Work necessary to enable
                    Tenant and its contractor to commence the Tenant's Work on

                                      -5-
<PAGE>   14

                    the second floor and in the portion of the first floor in
                    which the Premises are located.

     (j)  The Landlord Work necessary to trigger the "BASE BUILDING SUBSTANTIAL
COMPLETION DATE" shall be defined as the following items of work:

          i.)       The Landlord Work Necessary to Trigger Term Commencement
                    Date;
          ii.)      The Landlord Work Necessary to Trigger Third and Fourth
                    Floor Substantial Completion Date;
          iii.)     The Landlord Work Necessary to Trigger First and Second
                    Floor Substantial Completion Date;
          iv.)      The following items of Landlord's Work, to the extent not
                    included in clauses (i), (ii), and (iii) of this Article
                    4.0(j):

                    (a)  Curtainwall;
                    (b)  Roofing;
                    (c)  Windows;
                    (d)  Elevators;
                    (e)  Mechanical, Electrical & Plumbing Systems for Building
                         Core & Shell;
                    (f)  Building Cores including bathroom, mechanical,
                         electrical, and telephone/data rooms;
                    (g)  Building Lobby and Lobby interior finishes to the
                         extent which would be necessary to satisfy the
                         Certificate of Occupancy Test, as defined in Article
                         4.0(l);
                    (h)  Mechanical/Electrical & Plumbing finishes;
                    (i)  Base Building Fire Alarm Panels & Life Safety Systems;
                    (j)  Exterior walkways at least five (5) feet wide and
                         sufficient to permit access to and egress from the
                         Premises and adjacent public streets and parking areas,
                         as well as around the perimeter of the Building; and
                    (k)  All elements of Landlord's Work necessary to satisfy
                         the Certificate of Occupancy Test, as further defined
                         in Article 4.0(l).

Any portion of Landlord's Work which is not completed on or before the Base
Building Substantial Completion Date which affects a particular portion of the
Premises, or the access thereto, shall be completed within thirty (30) days
after a Certificate of Occupancy has been issued for such portion of the
Premises, except for (x) items of Landlord Work which are not complete due to
delays caused by weather (for those items which are weather-sensitive), and (y)
items of Landlord Work which are not complete due to delays caused by long lead
time items and causes beyond Landlord's reasonable control (provided, however,
that items of Landlord Work which are not complete due to delays caused by long
lead time items and causes beyond Landlord's reasonable control shall in any
event be completed within ninety (90) days after the issuance of the Certificate
of Occupancy for the portion of the Premises in question). Without limiting the
foregoing, the final balancing of mechanical systems need not be completed as of
the Rent Commencement Date, however, the air handling units serving the Premises
shall be

                                      -6-
<PAGE>   15

operational (the date such units are made operational being herein referred to
as the "HVAC Operational Date").

     (k)  BUILDING TIGHT. Any floor shall be deemed to be "Building Tight" if
all of the following have been achieved:

          i.)       The roof of the Building has been installed and is
                    weather-tight;
          ii.)      The windows on such floor have been installed and are
                    weather-tight;
          iii.)     The precast concrete on such floor has been installed and
                    is weather-tight;
          iv.)      All core walls facing the tenanted areas of such floor have
                    been substantially completed;
          v.)       The perimeter wall of the Building on such floor has been
                    installed, is weather tight and has interior drywall ready
                    for finish treatment;
          vi.)      Temporary power is available to Tenant on such floor;
          vii.)     All base building mechanical systems which are to be
                    provided to such floor have been stubbed to such floor.

     (l)  CERTIFICATE OF OCCUPANCY TEST.

          i.)  As a Condition to the Base Building Substantial Completion Date.
Reference is made to clauses (g) and (j) of Article 4.0(j)(iv), which provide
that, as a condition to achieving the Base Building Substantial Completion Date,
Landlord's Work must have been completed to the extent necessary to enable
Tenant to obtain a Certificate of Occupancy for the Premises (hereinafter
referred to as the "Certificate of Occupancy Test"). Landlord shall apply to the
Building Inspector of the City of Cambridge ("Building Inspector") for a
Certificate of Occupancy with respect to Landlord's Work ("Base Building") in
order to assist the parties in determining whether the Base Building Substantial
Completion Date has occurred. If the Building Inspector issues a Base Building
Certificate of Occupancy, the Certificate of Occupancy Test shall be
conclusively deemed to have been satisfied. The parties acknowledge that: (a) if
Tenant's Work has not progressed to the point where Tenant is able to apply for
a Certificate of Occupancy with respect to at least a portion of the Premises,
the Building Inspector may not be willing to perform such inspection, (b) given
that Tenant's Work includes a portion of the sprinkler system, the Building
Inspector may not be able to issue a Base Building Certificate of Occupancy if
Tenant's Work is not complete, and (c) other incomplete portions of Tenant's
Work may prevent Landlord from obtaining a Base Building Certificate of
Occupancy. If the Building Inspector is willing to perform such inspection and
if the Building Inspector denies the issuance of the Base Building Certificate
of Occupancy based solely on deficiencies identified by the Building Inspector
in Landlord's Work, then the Certificate of Occupancy Test shall not be deemed
satisfied until Landlord corrects such deficiencies to the satisfaction of the
Building Inspector. If, despite Landlord's application for a Base Building
Certificate of Occupancy, the Building Inspector does not perform such
inspection, or if the Building Inspector performs such inspection, but does not
identify any deficiencies in Landlord's Work and does not issue a Base Building
Certificate of Occupancy, then the Certificate of Occupancy Test may still be
satisfied as follows: Landlord shall notify Tenant when it believes that all of
Landlord's Work necessary for Tenant to obtain a Certificate of Occupancy has
been substantially completed ("Landlord's Completion Notice"). If Tenant
disputes Landlord's assertion of substantial

                                      -7-
<PAGE>   16

completion, it shall so notify Landlord within ten (10) days after receipt of
Landlord's Completion Notice, whereupon such dispute shall be immediately
submitted to arbitration in accordance with the provisions of Article 29.5. The
parties hereby acknowledge that Tenant, and not Landlord, is responsible for all
items of Tenant's Work which must be completed in order to enable Tenant to
obtain a Certificate of Occupancy for the Premises and in no event shall
Landlord be deemed to have failed to satisfy the Certificate of Occupancy Test
based upon any deficiency or lack of completion of Tenant's Work.

          ii.) Tenant's Inability to Obtain a Certificate of Occupancy after the
Occurrence of the Base Building Substantial Completion Date. If the Base
Building Substantial Completion Date (i.e. and the Rent Commencement Date)
occurs prior to the issuance of a Certificate of Occupancy with respect to any
portion of the Premises, and if, subsequently Tenant is denied a Certificate of
Occupancy with respect to any portion of the Premises, solely by reason of any
deficiency in Landlord's Work, then: (x) Landlord shall, as promptly as
possible, remedy such deficiency so as to remove such impediment to Tenant's
obtaining such Certificate of Occupancy, and (y) Tenant's obligation to pay
Yearly Rent and other charges due under the Lease in respect of the portion of
the Premises which Tenant is unable to occupy because it cannot obtain such
Certificate of Occupancy shall be fully abated during the period of time
commencing as of the date that Tenant is denied such Certificate of Occupancy
until Landlord cures such deficiency in Landlord's Work so that it is no longer
prevents Tenant from obtaining such Certificate of Occupancy.

     (m)  TENANT DELAY. A "Tenant Delay" shall be defined as any act or omission
by Tenant, or any agent, employee, consultant, contractor, or subcontractor of
Tenant, which causes an actual delay in the performance of Landlord's Work
Necessary to Trigger Full Rent Commencement Date. Notwithstanding the foregoing,
no event shall be deemed to be a Tenant Delay until and unless Landlord has
given Tenant written notice ("Tenant Delay Notice") advising Tenant: (i) that a
Tenant Delay is occurring, (ii) of the basis on which Landlord has determined
that a Tenant Delay is occurring, and (iii) the actions which Landlord believes
that Tenant must take to eliminate such Tenant Delay. No period of time prior to
the time that Tenant receives a Tenant Delay Notice shall be included in the
period of time charged to Tenant pursuant to such Tenant Delay Notice.

     (n)  LANDLORD DELAY. A "Landlord Delay" shall be defined as any act or
omission by Landlord or any agent, employee, consultant, contractor or
subcontractor of Landlord which: (i) is not a result of the priority granted to
Landlord's Work as set forth in Article 4.2(c) hereof, and (ii) causes an actual
delay in the performance of Tenant's Work. Notwithstanding the foregoing, except
as set forth in Article 4.2(e), no event shall be deemed to be a Landlord Delay
until and unless Tenant has given Landlord written notice ("Landlord Delay
Notice") advising Landlord: (i) that a Landlord Delay is occurring, (ii) of the
basis on which Tenant has determined that a Landlord Delay is occurring, and
(iii) the actions which Tenant believes that Landlord must take to eliminate
such Landlord Delay. No period of time prior to the time that Landlord receives
a Landlord Delay Notice shall be included in the period of time charged to
Landlord pursuant to such Landlord Delay Notice.

     (o)  LANDLORD'S WARRANTY; SATISFACTION OF LANDLORD'S OBLIGATIONS UNDER
ARTICLE 4.

                                      -8-
<PAGE>   17

     i.)  Landlord's Warranty. Landlord warrants to Tenant that: (x) materials
and equipment furnished in the performance of Landlord's Work will be of good
quality and new unless otherwise required or permitted by the Base Building
Specifications, (y) Landlord's Work will be free from defects not inherent in
the quality required or permitted under the Base Building Specifications, and
(z) Landlord's Work will conform the requirements of the Base Building
Specifications. Any portion of Landlord's Work not conforming to the
requirements of this clause (i), including substitutions not properly approved
and authorized, may be considered defective. Landlord's warranty excludes remedy
for damage or defect caused by abuse, modifications not executed by Landlord,
improper or insufficient maintenance (other than by Landlord, where Landlord is
required to perform maintenance on the item or system in question), improper
operation (other than by Landlord, where Landlord operates the item or system in
question), or normal wear and tear and normal usage.

     ii.) Warranty Period. Landlord shall be deemed to have satisfied all of its
obligations under this Article 4 (including, without limitation, Landlord's
warranty obligations under this Article 4.0(o) and under Article 4.3) except to
the extent that, on or before the Warranty Expiration Date, as hereinafter
defined, Tenant gives written notice to Landlord in accordance with the
provisions of Article 27 setting forth with specificity the manner in which
Tenant believes that Landlord has failed to comply with its obligations under
this Article 4. The "Warranty Expiration Date" shall be defined as the date
three hundred fifty-eight (358) days after the Full Rent Commencement Date.

     iii.) Repair of Defective Work. Landlord agrees that it shall, without cost
to Tenant, correct any portion of Landlord's Work which is found not to be in
accordance with the requirements of the warranties set forth in this Article
4.0(o) and in Article 4.3, unless Tenant has previously given Landlord a written
acceptance of such condition, provided that: Tenant gives Landlord written
notice of such condition in accordance with the provisions of Article 27
promptly after it becomes aware of such condition, and in any event on or before
the Warranty Expiration Date. The provisions of this Article 4.0(o) shall not
relieve Landlord of any obligation which Landlord has to make repairs or to
perform maintenance pursuant to Article 8 of the Lease.

     (p)  Any dispute between the parties with respect to the provisions of this
Article 4 shall be submitted to arbitration in accordance with Article 29.5.

     4.1  TENANT'S REMEDIES BASED ON DELAYS IN LANDLORD'S WORK.

     (a)  If the Term Commencement Date shall not have occurred on or before
October 1, 2001 ("INITIAL OUTSIDE COMPLETION DATE") (which date shall be
extended for up to ninety (90) days on account of any Force Majeure Delays, as
hereinafter defined), Tenant shall have the right to terminate this Lease by
giving notice to Landlord of Tenant's desire to do so before such completion and
within the time period from the Initial Outside Completion Date (as so extended)
until the date which is thirty (30) days subsequent to the Initial Outside
Completion Date (as so extended); and, upon the giving of such notice, the Term
of this Lease shall cease and come to an end without further liability or
obligation on the part of either party unless, within thirty (30) days after
receipt of such notice, the Term Commencement Date occurs. If Tenant terminates
the Lease pursuant to this Paragraph (a), Landlord shall return to Tenant any
Letter of Credit given by Tenant to Landlord within fifteen (15) business days
after Landlord's receipt written request for such return from Tenant, and
Landlord shall reimburse Tenant an amount equal to the

                                      -9-
<PAGE>   18

lesser of: (x) Five Hundred Sixty-Eight Thousand Two Hundred Thirty
($568,230.00) Dollars, or (y) the actual cost incurred by Tenant through the
Effective Termination Date in preparing the plans and specifications for
Tenant's Work. Landlord shall make such payment to Tenant within thirty (30)
days after Tenant delivers to Landlord evidence reasonably satisfactory to
Landlord of the amount such costs. Landlord shall have the right to audit
Tenant's books and records with respect to Tenant's costs.

     (b)  If the Base Building Substantial Completion Date does not occur on or
before March 1, 2002 ("INTERIM OUTSIDE COMPLETION DATE") (which date shall be
extended (i) for the period of any Tenant Delays, and (ii) for up to ninety (90)
days on account of any Force Majeure Delays), Tenant shall have the right to
terminate this Lease by giving notice to Landlord of Tenant's desire to do so
before such completion and within the time period from the Interim Outside
Completion Date (as so extended) until the date which is thirty (30) days
subsequent to the Interim Outside Completion Date (as so extended); and, upon
the giving of such notice ("Effective Termination Date"), the Term of this Lease
shall cease and come to an end without further liability or obligation on the
part of either party unless the Base Building Substantial Completion Date occurs
on or before the date thirty (30) days after receipt of such notice (as so
extended). If Tenant has occupied part of the Premises for the Permitted Use
prior to such termination, then the Effective Termination Date with respect to
the part of the Premises so occupied shall be ninety (90) days subsequent to the
Interim Outside Completion Date (as so extended). If Tenant terminates the Lease
pursuant to this Paragraph (b), Landlord shall return to Tenant any Letter of
Credit given by Tenant to Landlord within fifteen (15) business days after
Landlord's receipt written request for such return from Tenant, and Landlord
shall reimburse Tenant an amount equal to the actual cost incurred by Tenant
through the Effective Termination Date in performing and designing the Tenant's
Work to the extent that such amount exceeds any portion of Landlord's
Contribution theretofore paid to or for the account of Tenant. Landlord shall
make such payment to Tenant within thirty (30) days after Tenant delivers to
Landlord evidence reasonably satisfactory to Landlord of the amount such costs.
Landlord shall have the right to audit Tenant's books and records with respect
to Tenant's costs.

     (c)  If the Base Building Substantial Completion Date does not occur on or
before June 1, 2002 ("FINAL OUTSIDE COMPLETION DATE") (which date shall be
extended for the period of any Tenant Delays), Tenant shall have the right to
terminate this Lease by giving notice to Landlord of Tenant's desire to do so
before such completion and within the time period from the Final Outside
Completion Date until the date which is thirty (30) days subsequent to the Final
Outside Completion Date; and, upon the giving of such notice ("Effective
Termination Date"), the Term of this Lease shall cease and come to an end
without further liability or obligation on the part of either party unless the
Base Building Substantial Completion Date occurs on or before the date thirty
(30) days after receipt of such notice. If Tenant has occupied part of the
Premises for the Permitted Use prior to such termination, then the Effective
Termination Date with respect to the part of the Premises so occupied shall be
ninety (90) days subsequent to the Final Outside Completion Date. If Tenant
terminates the Lease pursuant to this Paragraph (c), Landlord shall return to
Tenant any Letter of Credit given by Tenant to Landlord within fifteen (15)
business days after Landlord's receipt written request for such return from
Tenant, and Landlord shall reimburse Tenant an amount equal to the actual cost
incurred by Tenant through the Effective Termination Date in performing and
designing the Tenant's Work to the extent that such amount exceeds any portion
of Landlord's Contribution theretofore paid to or for the account of Tenant.
Landlord shall make such payment to Tenant within thirty (30) days after Tenant
delivers to

                                      -10-
<PAGE>   19

Landlord evidence reasonably satisfactory to Landlord of the amount such costs.
Landlord shall have the right to audit Tenant's books and records with respect
to Tenant's costs.

     (d)  FORCE MAJEURE DELAYS. For the purposes of this Article 4.1, "Force
Majeure Delays" shall be defined as any delays in the performance of Landlord's
Work to the extent arising from causes beyond Landlord's reasonable control
other than Tenant Delays, provided however, that no delay shall be deemed to be
a Force Majeure Delay unless Landlord advises Tenant in writing of such delay on
or before the date thirty (30) days after Landlord first becomes aware of such
delay.

     (e)  RENT CREDIT. If the Full Rent Commencement Date has not occurred for
all or a portion of the Premises on or before the Liquidated Damage Date, as
hereinafter defined, then with respect to those portion(s) of the Premises with
respect to which the Rent Commencement Date has not occurred, Tenant shall be
entitled to a credit against the Yearly Rent on a day-for-day basis for the
lesser of (i) the number of days from the Liquidated Damage Date to but not
including the Rent Commencement Date with respect to such portion(s) of the
Premises, and (ii) one hundred eighty (180) days. The "Liquidated Damage Date"
shall be defined as December 1, 2001.

     (f)  The remedies set forth in this Article 4.1 are Tenant's sole and
exclusive rights and remedies based upon any delay in the performance of
Landlord's Work. If Tenant terminates this Lease pursuant to this Article 4.1,
then the Third Amendment to the Building 500 Lease (as defined in Article 21.1
hereof) shall also thereby be automatically terminated and of no further force
and effect.

     4.2  TENANT'S WORK.

     (a)  Tenant shall, on or before the Outside Tenant Work Commencement Date,
commence the performance of the work ("Tenant's Work") necessary to prepare the
Premises for Tenant's occupancy, and Tenant shall thereafter diligently
prosecute the Tenant's Work to completion. The "OUTSIDE TENANT WORK COMMENCEMENT
DATE" shall be defined as the date nine (9) months after the Term Commencement
Date, provided that if Tenant is delayed in the commencement of Tenant's Work by
reason of causes beyond Tenant's reasonable control, the Outside Tenant Work
Commencement Date shall be extended by the lesser of: (i) the period of time
which Tenant is so delayed, or (ii) three (3) additional months (i.e. in no
event shall the Outside Tenant Work Commencement Date occur later than the date
one (1) year after the Term Commencement Date).

     (b)  Tenant shall substantially complete Tenant's Work on or before the
Outside Tenant Work Completion Date. The "OUTSIDE TENANT WORK COMPLETION DATE"
shall be defined as the date fifteen (15) months after the Full Rent
Commencement Date, provided that if Tenant is delayed in the performance of
Tenant's Work by reason of causes beyond Tenant's reasonable control, the
Outside Tenant Work Completion Date shall be extended by the lesser of: (i) the
period of time which Tenant is so delayed, or (ii) three (3) additional months
(i.e. in no event shall the Outside Tenant Work Completion Date occur later than
the date eighteen (18) months after the Full Rent Commencement Date).

     (c)  COST OF TENANT'S WORK; PRIORITY OF WORK. Except for Landlord's
Contribution, as set forth in Article 6.2, all of the Tenant's Work shall be
performed at Tenant's

                                      -11-
<PAGE>   20

sole cost and expense, and shall be performed in accordance with the provisions
of this Lease (including, without limitation, Articles 11 and 12). Tenant and
Landlord shall each take necessary reasonable measures to the end that Tenant's
contractors and Landlord's contractors shall cooperate in all ways with
Landlord's contractors to avoid any delay in either Landlord's Work or Tenant's
Work or any conflict with the performance of either Landlord's Work or Tenant's
Work, Tenant acknowledging, however, that in the case of conflict that is not
reasonably avoidable, the performance of Landlord's Work shall have priority.
Tenant shall pay to Landlord, as additional rent, within ten (10) days of
billing therefor, charges (which shall be reasonably based on Tenant's usage)
for the use of elevators and/or hoisting in connection with the performance of
Tenant's Work. Tenant shall have access to the Premises and the Building on a
24-hour a day, 365-day a year basis in order to perform Tenant's Work. Landlord
and Tenant recognize that to the extent Tenant elects to perform some or all of
Tenant's Work during times other than normal construction hours, Landlord will
need to make arrangements to have supervisory personnel on site. Accordingly,
Landlord and Tenant agree as follows: Tenant shall give Landlord at least five
(5) days' written notice of any time outside of normal construction hours (i.e.,
Monday-Friday, 7 a.m. to 3 p.m., excluding holidays) when Tenant intends to
perform portions of Tenant's Work (the "After Hours Work"). Landlord shall pay
the cost of the first one hundred hours, in the aggregate, of Landlord's
supervisory personnel overseeing the After Hours Work. Tenant shall reimburse
Landlord, within thirty (30) days after demand therefor, for the cost of all
additional hours of Landlord's supervisory personnel overseeing the After Hours
Work. Landlord shall notify Tenant of the after hours hourly rates (which shall
be normal and customary) for such supervisory personnel from time to time upon
written request.

     (d)  TENANT'S PLANS. In connection with the performance of Tenant's Work,
Tenant shall submit to Landlord for Landlord's reasonable approval an initial
set of plans ("Initial Plans"), progress plans from time to time ("Interim
Plans") and a full set of construction drawings ("Final Plans") for Tenant's
Work (collectively "the Plans"). The Final Plans shall contain at least the
information required by, and shall conform to the requirements of, Exhibit 3.
Landlord's approval of the Initial Plans and the Interim Plans (and the Final
Plans, provided that the Final Plans are consistent with the Initial Plans and
the Interim Plans and contain at least the information required by, and conform
to the requirements of, said Exhibit 3), shall not be unreasonably withheld,
conditioned or delayed and shall comply with the requirements to avoid aesthetic
or other conflicts with the design and function of the balance of the Building.
Landlord's approval is solely given for the benefit of Landlord under this
Article 4.2 and neither Tenant nor any third party shall have the right to rely
upon Landlord's approval of Tenant's Plans for any other purpose whatsoever.
Without limiting the foregoing, Tenant shall be responsible for all elements of
the design of Tenant's plans (including, without limitation, compliance with
law, functionality of design, the structural integrity of the design, the
configuration of the Premises and the placement of Tenant's furniture,
appliances and equipment), and Landlord's approval of Tenant's Plans shall in no
event relieve Tenant of the responsibility for such design.

     (e)  TIME PERIODS FOR LANDLORD'S RESPONSE TO TENANT'S PLANS. Landlord
agrees to respond to any Initial Plans within ten (10) days of receipt thereof
and to Interim Plans and the Final Plans within fifteen (15) days of receipt
thereof. If Landlord has not responded to any submission of Tenant's Plans
within the ten (10) or fifteen (15) day, as applicable, time period set forth
above, then Tenant may send Landlord a notice of such failure to respond, which
notice ("Second Notice") shall contain the following language in bold face and
all capital letters: "SECOND NOTICE. FAILURE TO RESPOND TO THIS NOTICE WITHIN
FIVE (5)

                                      -12-
<PAGE>   21

DAYS SHALL CONSTITUTE A LANDLORD DELAY UNDER THE LEASE, WHICH MAY ENTITLE TENANT
TO A RENT ABATEMENT." If Landlord does not respond to the submission of Tenant's
Plans within five (5) days after receipt of the Second Notice, then each
additional day after five (5) days before Landlord responds to such submission
shall constitute a Landlord Delay.

     (f)  TENANT'S HOIST. Subject to Landlord's prior written approval of
Tenant's plans and specifications therefor (which approval shall not be
unreasonably withheld, conditioned, or delayed), Tenant shall have the right,
during the performance of Tenant's Work, to install a hoist at the Building in
order to enable Tenant's contractor to perform Tenant's Work. Tenant shall
maintain such hoist in good condition and in a manner which does not interfere
with the performance of Landlord's Work. The initial location of such hoist
shall be as reasonably approved by Tenant, recognizing the priority given to
Landlord's Work in Article 4.2(c) hereof. Once such hoist is installed, Tenant
shall not be required to relocate such hoist, except that Tenant shall remove
such hoist from the Building at the time that Landlord makes available to Tenant
an elevator for Tenant's exclusive use. Tenant shall repair any damage to the
Building caused by the installation or removal of such hoist.

     (g)  GAS LINE. Subject to (i) Landlord's prior written approval of Tenant's
plans and specifications therefor (which approval shall not be unreasonably
withheld, conditioned, or delayed), and (ii) Tenant having obtained all
necessary governmental approvals therefor, Landlord shall bring natural gas to
the perimeter of the Building at Landlord's expense and Tenant shall have the
right to tie into the same at its expense for the purpose of serving Tenant's
back-up generator.

     4.3  QUALITY AND PERFORMANCE OF WORK. All construction work required or
permitted by this Lease (whether constituting part of Landlord's Work or
Tenant's Work) shall be done in a good and workmanlike manner and in compliance
with all applicable laws, ordinances, rules, regulations, statutes, by-laws,
court decisions, and orders and requirements of all public authorities ("Legal
Requirements") and all insurance requirements of this Lease. All of Tenant's
Work shall be coordinated with any work being performed by, or for, Landlord,
and in such manner as to maintain harmonious labor relations. Each party
authorizes the other to rely in connection with design and construction upon the
written approval or other written authorizations on the party's behalf by any
Construction Representative of the party designated by the party. Each party's
initial Construction Representative is designated on Exhibit 1.

5.   USE OF PREMISES

     5.1  PERMITTED USE. Tenant shall continuously during the term hereof occupy
and use the Premises only for the purposes as stated in Exhibit 1 and for no
other purposes. Service and utility areas (whether or not a part of the
Premises) shall be used only for the particular purpose for which they were
designed. Without limiting the generality of the foregoing, Tenant agrees that
it shall not use the Premises or any part thereof, or permit the Premises or any
part thereof to be used for the preparation or dispensing of food, whether by
vending machines or otherwise. Notwithstanding the foregoing, but subject to the
other terms and provisions of this Lease, Tenant may, with Landlord's prior
written consent, which consent shall not be unreasonably withheld, install at
its own cost and expense so-called hot-cold water fountains, coffee makers and
refrigerator-sink-stove combinations for the preparation of beverages and foods,
provided that no cooking, frying, etc., are carried on in the Premises to such
extent as

                                      -13-
<PAGE>   22

requires special exhaust venting, Tenant hereby acknowledging that the Building
is not engineered to provide any such special venting. Landlord hereby agrees
that any equipment shown on Tenant's final approved plans and equivalent
equipment in substitution of such equipment shall not, if maintained in good
operating order, be deemed to violate the provisions of this Article 5.1.

     5.2  PROHIBITED USES. Notwithstanding any other provision of this Lease,
Tenant shall not use, or suffer or permit the use or occupancy of, or suffer or
permit anything to be done in or anything to be brought into or kept in or about
the Premises or the Building or any part thereof (including, without limitation,
any materials appliances or equipment used in the construction or other
preparation of the Premises and furniture and carpeting): (i) which would
violate any of the covenants, agreements, terms, provisions and conditions of
this Lease or otherwise applicable to or binding upon the Premises; (ii) for any
unlawful purposes or in any unlawful manner; (iii) which, in the reasonable
judgment of Landlord shall in any way (a) impair the appearance or reputation of
the Building; or (b) impair, interfere with or otherwise diminish the quality of
any of the Building services or the proper and economic heating, cleaning,
ventilating, air conditioning or other servicing of the Building; or Premises,
or with the use or occupancy of any of the other areas of the Building, or
occasion discomfort, inconvenience or annoyance, or injury or damage to any
occupants of the Premises or other tenants or occupants of the Building; or (iv)
which is inconsistent with the maintenance of the Building as an office building
of the first class in the quality of its maintenance, use, or occupancy. Tenant
shall not install or use any electrical or other equipment of any kind which, in
the reasonable judgment of Landlord, might cause any such impairment,
interference, discomfort, inconvenience, annoyance or injury.

     5.3  LICENSES AND PERMITS. If any governmental license or permit shall be
required for the proper and lawful conduct of Tenant's business, and if the
failure to secure such license or permit would in any way affect Landlord, the
Premises, the Building or Tenant's ability to perform any of its obligations
under this Lease, Tenant, at Tenant's expense, shall duly procure and thereafter
maintain such license and submit the same to inspection by Landlord. Tenant, at
Tenant's expense, shall at all times comply with the terms and conditions of
each such license or permit. Tenant shall furnish all data and information to
governmental authorities and Landlord as required in accordance with legal,
regulatory, licensing or other similar requirements as they relate to Tenant's
use or occupancy of the Premises or the Building.

6.   RENT AND SPECIAL ALLOWANCE

     6.1. RENT.

     (a)  During the term of this Lease the Yearly Rent and other charges, at
the rate stated in Exhibit 1, shall be payable by Tenant to Landlord by monthly
payments, as stated in Exhibit 1, in advance and without demand on the first day
of each month for and in respect of such month. The rent and other charges
reserved and covenanted to be paid under this Lease in respect of the Premises
shall commence on the Rent Commencement Date. If, by reason of any provisions of
this Lease, the rent reserved hereunder shall commence or terminate on any day
other than the first day of a calendar month, the rent for such calendar month
shall be prorated. The rent shall be payable to Landlord or, if Landlord shall
so direct in writing, to Landlord's agent or nominee, in lawful money of the
United States which shall be legal tender for payment of all debts and dues,
public and private, at the time of payment, at the office of the Landlord or

                                      -14-
<PAGE>   23

such place as Landlord may designate, and the rent and other charges in all
circumstances shall be payable without any setoff or deduction whatsoever.
Rental and any other sums due hereunder not paid on or before the date which is
five (5) business days after the date due shall bear interest for each month or
fraction thereof from the due date until paid computed at the annual rate of
three percentage points over the so-called prime rate then currently from time
to time charged to its most favored corporate customers by the largest national
bank (N.A.) located in the city in which the Building is located ("National
Bank"), or at any applicable lesser maximum legally permissible rate for debts
of this nature. In lieu of requiring Tenant to pay monthly installments of
Yearly Rent and other fixed monthly charges in the manner described above,
Tenant shall have the right to pay such amounts by means of an automated debit
system (the "Automatic Debit System") whereby any or all such payments shall be
debited from Tenant's account in a bank or financial institution designated by
Tenant and credited to Landlord's account in a bank or financial institution
designated by Landlord. In the event Tenant elects to pay monthly installments
of Yearly Rent and other fixed monthly charges by means of the Automatic Debit
System, Tenant, within thirty (30) days after written request by Landlord, shall
execute and deliver to Landlord any authorizations, certificates or other
documentation as may be required to establish and give effect to the Automatic
Debit System. Either party shall have the right to change its bank or financial
institution from time to time, provided that Tenant, no less than thirty (30)
days prior to the effective date of any such change, shall provide Landlord with
written notice of such change and any and all authorizations, certificates or
other documentation as may be required to establish and give effect to the
Automatic Debit System at Tenant's new bank or financial institution if Tenant
elects to continue to use such Automatic Debit System. Tenant shall promptly pay
all service fees and other charges imposed upon Tenant in connection with the
Automatic Debit System, and Tenant shall promptly reimburse Landlord for any
charges resulting from insufficient funds in Tenant's bank account (provided
however, that Tenant shall have the right to discontinue the use of the
Automatic Debit System at any time upon at least thirty (30) days' prior written
notice to Landlord). In the event that any Yearly Rent or other fixed monthly
charges are not paid on time as a result of insufficient funds in Tenant's
account, Tenant shall be liable for any interest in accordance with this
Article. Tenant shall remain liable to Landlord for all payments of Rent due
hereunder regardless of whether Tenant's account is incorrectly debited in any
given month, it being agreed that a debit of less than the full amount due shall
not be construed as a waiver by Landlord of its right to receive any unpaid
balance.

     (b)  Rentable Area. Landlord and Tenant acknowledge the Total Rentable Area
of the Premises, the Building and of the other buildings initially in the
Complex have been determined by agreement, and that the figures set forth in
Exhibit 1 shall be conclusive and binding on Landlord and Tenant with regard to
the Complex. In the event that Landlord alters any of the buildings in, or adds
other buildings to, the Complex, the Total Rentable Area of any such buildings
shall be included in the Total Rentable Area of the Complex when first occupied.

     6.2  LANDLORD'S CONTRIBUTION.

     (a)  As an inducement to Tenant's entering into this Lease, Landlord shall
provide to Tenant a special allowance equal to up to Thirty and 00/100 Dollars
($30.00) per square foot of Rentable Floor Area of the Premises initially
demised to Tenant (i.e. Three Million Four Hundred Nine Thousand Three Hundred
Eighty and 00/100 Dollars ($3,409,380.00)) ("Landlord's Contribution") to be
used by Tenant to pay for the cost of the Tenant's Work. For

                                      -15-
<PAGE>   24

the purposes hereof, the cost to be so reimbursed by Landlord shall include the
cost of leasehold improvements but not the cost of any of Tenant's personal
property, trade fixtures or trade equipment or any so-called soft costs.
Furthermore, in the event that Tenant does not build out all of the Premises,
Landlord's Contribution shall be limited to a maximum of Thirty and 00/100
Dollars ($30.00) per square foot of Rentable Floor Area of the Premises actually
built out by Tenant (the "Finished Area").

     (b)  Landlord shall pay Landlord's Proportion (as hereinafter defined) of
the cost shown on each requisition (as hereinafter defined) submitted by Tenant
to Landlord within twenty (20) days of submission thereof by Tenant to Landlord
until the entirety of Landlord's Contribution has been exhausted. For purposes
hereof, "Landlord's Proportion" shall be a fraction, the numerator of which is
Landlord's Contribution and the denominator of which is the total contract price
for Tenant's Work, and a "requisition" shall mean written documentation
(including, without limitation, invoices from Tenant's contractors, vendors,
service providers and consultants, lien waivers, and such other documentation as
Landlord or Landlord's mortgagee may reasonably request) showing in reasonable
detail the costs of the item in question or of the improvements installed to
date in the Premises, accompanied by certifications from Tenant that the amount
of the requisition in question does not exceed the cost of the items, services
and work covered by such requisition. Each requisition shall be accompanied by
evidence reasonably satisfactory to Landlord that items, services and work
covered by such requisition has been fully paid by Tenant and that the work has
been performed. Landlord shall have the right, upon reasonable advance notice to
Tenant, to inspect Tenant's books and records relating to each requisition in
order to verify the amount thereof. Tenant shall submit requisition(s) no more
often than monthly.

     (c)  Notwithstanding anything to the contrary herein contained:

          (i)  Landlord shall have no obligation to advance funds on account of
               Landlord's Contribution unless and until Landlord has received
               the requisition in question.

          (ii) Except with respect to work and/or materials previously paid for
               by Tenant, as evidenced by paid invoices and written lien waivers
               provided to Landlord, Landlord shall have the right to have
               Landlord's Contribution paid to directly to Tenant's
               contractor(s), consultants, service providers, and vendor(s). In
               no event shall Landlord's Contribution be applied to any fees
               paid to Tenant or any affiliate of Tenant.

          (iii) Landlord shall have no obligation to pay any portion of
               Landlord's Contribution in respect of any requisition submitted
               after the date ("Outside Requisition Date") which is the earlier
               of: (a) three (3) months after the completion of Tenant's Work,
               or (b) twenty-one (21) months after the Full Rent Commencement
               Date (provided, however, that if Tenant certifies to Landlord
               that it is engaged in a good faith dispute with its contractor,
               such Outside Requisition Date shall be extended while such
               dispute is ongoing, so long as Tenant is diligently prosecuting
               the resolution of such dispute). Tenant shall not be entitled to
               receive any portion of Landlord's Contribution except to the
               extent

                                      -16-
<PAGE>   25

               that it has submitted requisitions and/or made demand therefor,
               on or before the Outside Requisition Date.

          (iv) Tenant shall not be entitled to any unused portion of Landlord's
               Contribution.

          (v)  Landlord's obligation to pay any portion of Landlord's
               Contribution shall be conditioned upon there existing no default
               beyond the expiration of any applicable grace periods by Tenant
               in its obligations under the Lease at the time that Landlord
               would otherwise be required to make such payment.

7.   RENTABLE AREA

     Total Rentable Area of the Premises, the Building and the Complex have, as
of the Execution Date, been agreed to be the amounts set forth on Exhibit 1.

8.   SERVICES FURNISHED BY LANDLORD

     8.1  ELECTRIC CURRENT.

          (a)  As stated in Exhibit 1, Landlord will require Tenant to contract
directly with the company supplying electric current for the purchase and
obtaining by Tenant of electric current directly from such company to be billed
directly to, and paid for by, Tenant. Tenant shall have the right to choose
among companies supplying electric current to the Premises if there is more than
one such company available. Tenant acknowledges that such electric current
purchased directly by Tenant shall include the current used to operate the HVAC
equipment serving the Premises.

          (b)  Landlord shall (i) permit its risers, conduits and feeders to the
extent available, suitable and safely capable, to be used for the purpose of
enabling Tenant to purchase and obtain electric current directly from such
company, (ii) without cost or charge to Tenant, make such alterations and
additions to the electrical equipment and/or appliances in the Building as such
company shall specify for the purpose of enabling Tenant to purchase and obtain
electric current directly from such company, and (iii) at Landlord's expense,
furnish and install in or near the Premises any necessary metering equipment
used in connection with measuring Tenant's consumption of electric current and
Tenant, at Tenant's expense, shall maintain and keep in repair such metering
equipment.

          (c)  If Tenant shall require electric current for use in the Premises
in excess of the capacity available at the commencement of the term of this
Lease and if (i) in Landlord's reasonable judgment, Landlord's facilities are
inadequate for such excess requirements or (ii) such excess use shall result in
an additional burden on the Building air conditioning system and additional cost
to Landlord on account thereof then, as the case may be, (x) Landlord upon
written request and at the sole cost and expense of Tenant, will furnish and
install such additional wire, conduits, feeders, switchboards and appurtenances
as reasonably may be required to supply such additional requirements of Tenant
if current therefor be available to Landlord, provided that the same shall be
permitted by applicable laws and insurance regulations and shall not cause
damage to the Building or the Premises or cause or create a dangerous or
hazardous condition or

                                      -17-
<PAGE>   26

entail excessive or unreasonable alterations or repairs or interfere with or
disturb other tenants or occupants of the Building or (y) Tenant shall reimburse
Landlord for such additional cost, as aforesaid.

          (e)  Landlord, at Tenant's expense and upon Tenant's request, shall
purchase and install all replacement lamps of types generally commercially
available (including, but not limited to, incandescent and fluorescent) used in
the Premises.

          (f)  Subject to Article 8.8(b), Landlord shall not in any way be
liable or responsible to Tenant for any loss, damage or expense which Tenant may
sustain or incur if the quantity, character, or supply of electrical energy is
changed or is no longer available or suitable for Tenant's requirements.

          (g)  Tenant agrees that it will not make any material alteration or
material addition to the electrical equipment and/or appliances in the Premises
without the prior written consent of Landlord in each instance first obtained,
which consent will not be unreasonably withheld, and will promptly advise
Landlord of any other alteration or addition to such electrical equipment and/or
appliances.

     8.2  WATER. Landlord shall furnish hot and cold water for ordinary premises
cleaning, toilet, lavatory and drinking purposes. If Tenant requires, uses or
consumes water for any purpose other than for the aforementioned purposes,
Landlord may (i) assess a reasonable charge for the additional water so used or
consumed by Tenant or (ii) install a water meter and thereby measure Tenant's
water consumption for all purposes. In the latter event, Landlord shall pay the
cost of the meter and the cost of installation thereof and shall keep said meter
and installation equipment in good working order and repair. Tenant agrees to
pay for water consumed, as shown on said meter, together with the sewer charge
based on said meter charges, as and when bills are rendered, and on default in
making such payment Landlord may pay such charges and collect the same from
Tenant, but only to the extent that the charges shown on the meter exceed the
consumption reasonably expected for ordinary premises cleaning, toilet, lavatory
and drinking purposes. All piping and other equipment and facilities for use of
water outside the building core will be installed and maintained by Landlord at
Tenant's sole cost and expense.

     8.3  ELEVATORS, HEAT, CLEANING.

          (a)  Landlord at its expense shall: (i) provide necessary elevator
facilities (which may be manually or automatically operated, either or both, as
Landlord may from time to time elect) on Mondays through Fridays, excepting
legal holidays, from 8:00 a.m. to 6:00 p.m. and on Saturdays, excepting legal
holidays, from 8:00 a.m. to 1:00 p.m. (called "business days") and have one
elevator in operation available for Tenant's use, non-exclusively, together with
others having business in the Building, at all other times; (ii) furnish heat
(substantially equivalent to that being furnished in comparably aged similarly
equipped office buildings in the same city) to the Premises during the normal
heating season on business days; and (iii) cause the office areas and the
network operations center of the Premises to be cleaned on business days (except
on Saturdays) provided the same are kept in order by Tenant. Either Exhibit 4
(if annexed hereto) or, otherwise, the cleaning standards generally prevailing
in first-class office buildings in the city or town where the Building is
located, shall represent substantially the extent and scope of the cleaning by
Landlord referred to in this Article 8.3.

                                      -18-
<PAGE>   27

          (b)  The parties agree and acknowledge that, despite reasonable
precautions in selecting cleaning and maintenance contractors and personnel, any
property or equipment in the Premises of a delicate, fragile or vulnerable
nature may nevertheless be damaged in the course of cleaning and maintenance
services being performed. Accordingly, Tenant shall take reasonable protective
precautions with such property and equipment (including, without limitation,
computers or other data processing components or equipment and optical or
electronic equipment, etc.), e.g., housing the property and equipment in a
separate, locked room, so as to render it inaccessible to the Building's
cleaning personnel.

     8.4  AIR CONDITIONING. Landlord shall through the air conditioning
equipment of the Building furnish to and distribute in the Premises air
conditioning as normal seasonal changes may require on business days during the
hours as aforesaid in Article 8.3 when air conditioning may reasonably be
required for the comfortable occupancy of the Premises by Tenant. Tenant agrees
to use reasonable efforts to lower and close the blinds or drapes when necessary
because of the sun's position, whenever the air conditioning system is in
operation, and to cooperate fully with Landlord with regard to, and to abide by
all the reasonable regulations and requirements which Landlord may prescribe for
the proper functioning and protection of the air conditioning system. The air
conditioning system referred to in this Article 8.4 shall be capable of
maintaining the following: the air conditioning system referred to in this
Article 8.4 shall be capable of providing 75(Degree)F dry bulb and 55% of
relative humidity with outside conditions of 91(Degree)F dry bulb and
73(Degree)F wet bulb.

     8.5  ADDITIONAL HEAT, CLEANING AND AIR CONDITIONING SERVICES.

          (a)  Landlord will use reasonable efforts upon reasonable advance
written notice from Tenant of its requirements in that regard, to furnish
additional heat, cleaning or air conditioning services to the Premises on days
and at times other than as above provided.

          (b)  There shall be no charge for additional heat or air conditioning,
as Tenant pays the cost of electricity therefor directly pursuant to Article
8.1. Tenant will pay to Landlord a reasonable charge (i) for any such additional
cleaning service required by Tenant, (ii) for any extra cleaning of the Premises
required because of the carelessness or indifference of Tenant or because of the
nature of Tenant's business, and (iii) for any cleaning done at the request of
Tenant of any portions of the Premises which may be used for storage, shipping
room or other non-office purposes. If the cost to Landlord for cleaning the
Premises shall be increased due to the installation in the Premises, at Tenant's
request, of any materials or finish other than those which are building
standard, Tenant shall pay to Landlord an amount equal to such increase in cost.

     8.6  ADDITIONAL AIR CONDITIONING EQUIPMENT. In the event Tenant requires
additional air conditioning for business machines, meeting rooms or other
special purposes, or because of occupancy or excess electrical loads, any
additional air conditioning units, chillers, condensers, compressors, ducts,
piping and other equipment, such additional air conditioning equipment will be
installed and maintained by Landlord at Tenant's sole cost and expense, but only
if, in Landlord's reasonable judgment, the same will not cause damage or injury
to the Building or create a dangerous or hazardous condition or entail excessive
or unreasonable alterations, repairs or expense or interfere with or disturb
other tenants; and Tenant shall

                                      -19-
<PAGE>   28

reimburse Landlord in such an amount as will compensate it for the cost incurred
by it in operating such additional air conditioning equipment.

     8.7  REPAIRS. Except as otherwise provided in Articles 18 and 20, and
subject to Tenant's obligations in Article 14, Landlord shall keep and maintain
the roof, exterior walls, structural floor slabs, columns, elevators, public
stairways and corridors, lavatories, equipment (including, without limitation,
sanitary, electrical, heating, air conditioning, or other systems) and other
common facilities of the Building in good condition and repair.

     8.8  INTERRUPTION OR CURTAILMENT OF SERVICES.

          (a)  When necessary by reason of accident or emergency, or for
repairs, alterations, replacements or improvements which in the reasonable
judgment of Landlord are desirable or necessary to be made, or of difficulty or
inability in securing supplies or labor, or of strikes, or of any other cause
beyond the reasonable control of Landlord, whether such other cause be similar
or dissimilar to those hereinabove specifically mentioned until said cause has
been removed, Landlord reserves the right to interrupt, curtail, stop or suspend
(i) the furnishing of heating, elevator, air conditioning, and cleaning services
and (ii) the operation of the plumbing and electric systems. Landlord shall
exercise reasonable diligence to eliminate the cause of any such interruption,
curtailment, stoppage or suspension, but there shall be no diminution or
abatement of rent or other compensation due from Landlord to Tenant hereunder,
nor shall this Lease be affected or any of the Tenant's obligations hereunder
reduced, and the Landlord shall have no responsibility or liability for any such
interruption, curtailment, stoppage, or suspension of services or systems.

          (b)  Notwithstanding anything to the contrary in this Lease contained,
if the Premises shall lack any service which Landlord is required to provide
hereunder, or if Tenant's use and occupancy of the Premises shall be disturbed
in violation of Article 10 hereof (thereby rendering the Premises or a portion
thereof substantially untenantable) so that, for the Landlord Service
Interruption Cure Period, as hereinafter defined, the continued operation in the
ordinary course of Tenant's business is materially adversely affected and if
Tenant ceases to use the affected portion of the Premises during the period of
untenantability as the direct result of such lack of service or disturbance,
then, provided that Tenant ceases to use the affected portion of the Premises
during the entirety of the Landlord Service Interruption Cure Period and that
such untenantability and Landlord's inability to cure such condition is not
caused by the fault or neglect of Tenant or Tenant's agents, employees or
contractors, Yearly Rent, Operating Expense Excess and Tax Excess shall
thereafter be abated in proportion to such untenantability until the day such
condition is completely corrected. For the purposes hereof, the "Landlord
Service Interruption Cure Period" shall be defined as five (5) consecutive
business days after Landlord's receipt of written notice from Tenant of the
condition causing untenantability in the Premises, provided however, that the
Landlord Service Interruption Cure Period shall be ten (10) consecutive business
days after Landlord's receipt of written notice from Tenant of such condition
causing untenantability in the Premises if either the condition was caused by
causes beyond Landlord's control or Landlord is unable to cure such condition as
the result of causes beyond Landlord's control.

          (c)  The provisions of Paragraph (b) of this Article 8.8 shall not
apply in the event of untenantability caused by fire or other casualty, or
taking (see Articles 18 and 20).

                                      -20-
<PAGE>   29

     8.9  ENERGY CONSERVATION. Notwithstanding anything to the contrary in this
Article 8 or in this Lease contained, Landlord may institute, and Tenant shall
comply with, such policies, programs and measures as may be necessary, required,
or expedient for the conservation and/or preservation of energy or energy
services, provided however, that Landlord does not, by reason of such policies,
programs and measures, reduce the level of energy or energy services being
provided to the premises below the level of energy or energy services then being
provided in comparably aged, first-class office buildings in the greater Boston
area, or as may be necessary or required to comply with applicable codes, rules
regulations or standards.

     8.10 MISCELLANEOUS. Other than air conditioning, all services provided by
Landlord to Tenant are based upon an assumed maximum Premises population of one
person per one hundred fifty (150) square feet of Total Rentable Area. Tenant
acknowledges that if it exceeds the foregoing limitation, Landlord may incur
costs including, without limitation, additional costs due to the additional load
on building systems. Tenant agrees to reimburse Landlord for the amount of such
costs (if any), as reasonably determined by Landlord, due to a Premises
population in excess of the foregoing maximum.

9.   ESCALATION

     9.1  DEFINITIONS. As used in this Article 9, the words and terms which
follow mean and include the following:

     (a)  "Operating Year" shall mean a calendar year in which occurs any part
of the term of this Lease.

     (b)  "Operating Cost Base" shall be the amount as stated in Exhibit 1.

     (c)  Subject to the provisions of Article 6(b),"Tenant's Building
Percentage" and "Tenant's Complex Percentage" shall be the respective figures as
stated in Exhibit 1.

     (d)  "Taxes":

          Subject to Article 9.7:

          (d1) "Building Taxes" shall mean the real estate taxes and other
     taxes, levies and assessments imposed upon the Building and that portion of
     the land of the Complex comprised of the Building's footprint and an area
     surrounding the Building as shown on Exhibit 2-1, and upon any personal
     property of Landlord used in the operation of the Building, or on
     Landlord's interest in the Building or such personal property (provided
     that to the extent such taxes, levies, and assessments are also allocable
     to property other than the Building, such amounts shall be allocated among
     all real estate which is so jointly assessed based on the assessor's
     records or, if the records do not provide a separate allocation, based on
     square footage of the buildings in question); charges, fees and assessments
     for transit, housing, police, fire or other services or purported benefits
     to the Building; service or user payments in lieu of taxes; and any and all
     other taxes, levies, betterments, assessments and charges arising from the
     ownership, leasing, operating, use or occupancy of the Building or based
     upon rentals derived therefrom, which are or shall be imposed by federal,
     state, county, municipal or other governmental authorities. Notwithstanding
     anything to the contrary herein contained, with respect to

                                      -21-
<PAGE>   30

     betterments or other extraordinary or special assessments, Tenant's
     obligations shall apply only to the extent such assessments are payable
     during and in respect of the term of the Lease if paid over the longest
     period permitted by law. The definition of Building Taxes is subject to the
     provisions of Article 9.1(d4)

          (d2) "Land" shall mean all of the land of the Complex (but not any
     improvements thereon which are separately assessed, except for common
     facilities as set forth in Paragraph (d3) below), excluding, however, the
     land on which the Garage and all other parking areas are located and the
     portions of land under each building in the Complex and an area surrounding
     each such building as shown on Exhibit 2-1, and reasonable similar areas
     designated by Landlord in connection with new buildings added to the
     Complex from time to time. Real estate taxes with respect to such parking
     areas are included in the parking fees charged to users and real estate
     taxes attributable to the land comprised of the footprint and such
     perimeter area of each building in the Complex shall be allocated on a
     building-by-building basis.

          (d3) "Land Taxes" shall mean the real estate taxes and other taxes,
     levies and assessments imposed upon the Land, upon any common facilities
     separately assessed as such by the tax assessor, and upon any personal
     property of Landlord used in connection with the Land, or on Landlord's
     interest in the Land or such personal property (provided that to the extent
     such taxes, levies, and assessments are also allocable to property other
     than the Land, such amounts shall be equitably allocated among all real
     estate which is so jointly assessed); charges, fees and assessments for
     transit, housing, police, fire or other governmental services or purported
     benefits to the Land; service or user payments in lieu of taxes; and any
     and all other taxes, levies, betterments, assessments and charges arising
     from the ownership, leasing, operation, or use of the Land or based upon
     rentals derived therefrom, which are or shall be imposed by federal, state,
     county, municipal or other governmental authorities. Land Taxes shall
     exclude any taxes on any parking garage located on the Land or which are
     otherwise assessed as part of Building Taxes. The definition of Land Taxes
     is subject to the provisions of Article 9.1(d4).

          (d4) As of the Execution Date, neither Building Taxes nor Land Taxes
     shall include any inheritance, estate, succession, gift, franchise, rental,
     income or profit tax, capital stock tax, capital levy or excise, or any
     income taxes arising out of or related to the ownership and operation of
     the Building or Complex, provided, however, that any of the same and any
     other tax, excise, fee, levy, charge or assessment, however described, that
     may in the future be levied or assessed as a substitute for or an addition
     to, in whole or in part, any tax, levy or assessment which would otherwise
     constitute "Taxes," whether or not now customary or in the contemplation of
     the parties on the Execution Date of this Lease, shall constitute "Taxes,"
     but only to the extent calculated as if the Complex were the only real
     estate owned by Landlord. "Taxes" shall also include reasonable expenses of
     tax abatement or other proceedings contesting assessments or levies.

     (e)  "Tax Base" shall be the amount stated in Exhibit 1 and shall apply to
a Tax Period of twelve (12) months. The Tax Base shall be reduced pro rata if
and to the extent that the Tax Period contains fewer than twelve (12) months.

                                      -22-
<PAGE>   31

     (f)  "Tax Period" shall be any fiscal/tax period in respect of which Taxes
are due and payable to the appropriate governmental taxing authority (i.e., as
mandated by the governmental taxing authority), any portion of which period
occurs during the term of this Lease, the first such Period being the one in
which the Rent Commencement Date (or, if there is more than one Rent
Commencement Date hereunder, the first such date) occurs.

     (g)  "Operating Costs":

          Subject to Article 9.7:

          (g1) Definition of Building Operating Costs. "Building Operating
     Costs" shall mean all costs incurred and expenditures of whatever nature
     made by Landlord in the operation and management, for repair and
     replacements, cleaning and maintenance of the non-retail portion of the
     Building, including, without limitation, vehicular and pedestrian
     passageways serving the Building, related equipment, facilities and
     appurtenances and cooling and heating equipment. For costs and expenditures
     made by Landlord in connection with the Building as a whole, Landlord shall
     make a reasonable allocation thereof between the retail and non-retail
     portions of the Building. A portion of Complex Operating Costs shall be
     included in Building Operating Costs in accordance with Subparagraphs g(3)
     and g(6).

          (g2) Definition of Complex Operating Costs. "Complex Operating Costs"
     shall mean all costs incurred and expenditures made by Landlord in the
     operation and management, repair and replacement, cleaning and maintenance
     of the common areas of the Complex, exclusive of the Garage, the Parking
     Areas, the Building, and the other buildings in the Complex. Any expenses
     incurred by Landlord that can be allocated on a building-by-building basis
     shall be so allocated in accordance with Subparagraph (g3). To the extent
     that a cost included in Complex Operating Costs is also allocable to
     property other than the Complex, such cost shall be equitably allocated to
     each parcel of property which benefits from such cost.

          (g3) The allocation of costs and expenditures among the various
     buildings in the Complex shall be on the basis of the ratio of the Total
     Rentable Area of each building in the Complex to the Total Rentable Area of
     the Complex, unless such allocation would result in a disproportionate
     charge based upon the relative usage of the service on which such cost is
     based, in which case such allocation shall be based upon such relative
     usage. Building Operating Costs and Complex Operating Costs shall include,
     without limitation, those categories of "Specifically Included Operating
     Costs", as set forth below, but shall not include "Excluded Costs", as
     hereinafter defined.

          (g4) Definition of Excluded Costs. "Excluded Costs" shall be defined
     as:

               (i)       mortgage charges (including interest, principal, points
                         and fees);

               (ii)      brokerage commissions;

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<PAGE>   32

               (iii)     salaries of executives and owners not directly
                         employed in the management/operation of the Complex;

               (iv)      the cost of work done by Landlord for a particular
                         tenant for which Landlord has the right to be
                         reimbursed by such tenant;

               (v)       subject to Subparagraph (g5) below, such portion of
                         expenditures as are not properly chargeable against
                         income;

               (vi)      any ground or underlying lease rental;

               (vii)     bad debt expenses;

               (viii)    costs incurred by Landlord to the extent that
                         Landlord is reimbursed by insurance proceeds or is
                         otherwise reimbursed, other than through the payment of
                         Operating Costs;

               (ix)      depreciation, amortization and interest payments,
                         except as expressly set forth in subparagraph (g5)
                         below and except on equipment, materials, tools,
                         supplies and vendor-type equipment purchased by
                         Landlord to enable Landlord to supply services Landlord
                         might otherwise contract for with a third party where
                         such depreciation, amortization and interest payments
                         would otherwise have been included in the charge for
                         such third party's services, all as determined in
                         accordance with generally accepted accounting
                         principles, consistently applied, and when depreciation
                         or amortization is permitted or required, the item
                         shall be amortized over its reasonably anticipated
                         useful life;

               (x)       advertising and promotional expenditures, and costs of
                         acquisition and maintenance of one-party signs in or on
                         the Building identifying the owner of the Building or
                         other tenants;

               (xi)      marketing costs, including leasing commissions,
                         attorneys' fees (in connection with the negotiation and
                         preparation of letters, deal memos, letters of intent,
                         leases, subleases and/or assignments), space planning
                         costs and other costs and expenses incurred in
                         connection with lease, sublease and/or assignment
                         negotiations and transactions with present or
                         prospective tenants or other occupants of the Building;

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<PAGE>   33

               (xii)     costs, including permit, license and inspection costs,
                         incurred with respect to the installation of tenants'
                         or other occupants' improvements or incurred in
                         renovating or otherwise improving, decorating, painting
                         or redecorating vacant space for tenants or other
                         occupants of the Building;

               (xiii)    expenses in connection with services or other
                         benefits which are offered to other tenants of the
                         Building or Complex but not to Tenant or for which
                         Tenant is charged directly, other than through
                         Operating Costs;

               (xiv)     fines, interest and penalties incurred by Landlord due
                         to the violation by Landlord or any tenant of the terms
                         and conditions of any lease of space in the Building;

               (xv)      management fees paid or charged by Landlord in
                         connection with the management of the Building to the
                         extent such management fee is in excess of the market
                         rate.

               (xvi)     salaries and other benefits paid to any executive
                         employees above the level of senior property manager of
                         the Complex;

               (xvii)    amounts paid to Landlord or to subsidiaries or
                         affiliates of Landlord for goods and/or services in the
                         Building to the extent the same exceeds the costs of
                         such goods and/or services rendered by unaffiliated
                         third parties on a competitive basis;

               (xviii)   Landlord's general corporate overhead and general
                         administrative expenses;

               (xix)     any compensation paid to clerks, attendants or other
                         persons in commercial concessions operated by Landlord;

               (xx)      services provided, taxes, attributable to, and costs
                         incurred in connection with the operation (as opposed
                         to the repair and maintenance thereof which shall be
                         included in Operating Costs) of any garage for the
                         Building, and any replacement garages or parking
                         facilities;

               (xxi)     costs incurred in connection with upgrading the
                         Building to comply with laws, rules, regulations and
                         codes in effect prior to the Term Commencement Date;

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<PAGE>   34

               (xxii)    fines, interest and penalties arising from the
                         negligence or willful misconduct of Landlord or other
                         tenants or occupants of the Building or their
                         respective agents, employees, licensees, vendors,
                         contractors or providers of materials or services;

               (xxiii)   costs arising from Landlord's political
                         contributions;

               (xxiv)    costs for sculpture, paintings or other objects of
                         art;

               (xxv)     costs associated with the operation of the business of
                         the entity which constitutes Landlord as the same are
                         distinguished from the costs of operation of the
                         Building, including accounting and legal matters, costs
                         of defending any lawsuits with any mortgagee (except as
                         the actions of Tenant may be in issue), costs of
                         selling, syndicating, financing, mortgaging or
                         hypothecating any of Landlord's interest in the
                         Building, costs incurred in connection with any
                         disputes between Landlord and its employees, between
                         Landlord and Building management, or between Landlord
                         and other tenants or occupants;

               (xxvi)    rentals for items which, if purchased rather than
                         rented, would constitute a capital cost, to the extent
                         that the rental payments exceed the costs which could
                         be included pursuant to paragraph (g5) below;

               (xxvii)   costs of electricity for plugs and lights provided
                         to other tenants' demised premises;

               (xxviii)  repair and replacement costs in connection with
                         defects in Landlord's Work which are incurred by
                         Landlord prior to the third (3rd) anniversary of the
                         Full Rent Commencement Date; and

               (xxix)    any costs related to any development, demolition or
                         construction activity in the Building or the Complex,
                         and any and all costs of construction mitigation
                         measures, including, without limitation, dust control,
                         cleaning, maintenance, debris removal, traffic control
                         and noise control, but the foregoing shall have no
                         effect on the inclusion of the cost of normal cleaning
                         services for the Complex.

          (g5) Capital Expenditures.

               (i)  REPLACEMENTS. If, during the term of this Lease, Landlord
          shall replace any capital items or make any capital expenditures

                                      -26-
<PAGE>   35

          (collectively called "Capital Expenditures") the total amount of which
          is not properly includable in Operating Costs for the Operating Year
          in which they were made, in accordance with generally accepted
          accounting principles and practices in effect at the time of such
          replacement, there shall nevertheless be included in such Operating
          Costs and in Operating Costs for each succeeding Operating Year the
          amount, if any, by which the Annual Charge-Off (determined as
          hereinafter provided) of such Capital Expenditure (less insurance
          proceeds, if any, collected by Landlord by reason of damage to, or
          destruction of the capital item being replaced) exceeds the Annual
          Charge-Off of the Capital Expenditure for the item being replaced.

               (ii) NEW CAPITAL ITEMS. If a new capital item is acquired which
          does not replace another capital item which was worn out, has become
          obsolete, etc., and such new capital item being acquired is either (i)
          required by law or (ii) reasonably projected to reduce Operating
          Costs, then there shall be included in Operating Costs for each
          Operating Year in which and after such capital expenditure is made the
          Annual Charge-Off of such capital expenditure.

               (iii) ANNUAL CHARGE-OFF. "Annual Charge-Off" shall be defined as
          the annual amount of principal and interest payments which would be
          required to repay a loan ("Capital Loan") in equal monthly
          installments over the Useful Life, as hereinafter defined, of the
          capital item in question on a direct reduction basis at an annual
          interest rate equal to the Capital Interest Rate, as hereinafter
          defined, where the initial principal balance is the cost of the
          capital item in question.

               (iv) USEFUL LIFE. "Useful Life" shall be reasonably determined by
          Landlord in accordance with generally accepted accounting principles
          and practices in effect at the time of acquisition of the capital
          item. Notwithstanding the foregoing, if Landlord reasonably concludes
          on the basis of engineering estimates that a particular capital
          expenditure will effect savings in Complex operating expenses
          including, without limitation, energy-related costs, and that such
          annual projected savings will exceed the Annual Charge-Off of Capital
          Expenditures computed as aforesaid, then and in such events, the
          Annual Charge-Off shall be determined based upon a Useful Life which
          would cause the principal and interest payments in a full repayment of
          the Capital Loan in question to equal the amount of projected savings
          of such Useful Life.

               (v)  CAPITAL INTEREST RATE. "Capital Interest Rate" shall be
          defined as an annual rate of either one percentage point over the AA
          Bond rate (Standard & Poor's corporate composite or, if unavailable,
          its equivalent) as reported in the financial press at the time the
          capital expenditure is made or, if the capital item is acquired
          through third-party financing, then the actual (including fluctuating)
          rate paid by Landlord in financing the acquisition of such capital
          item.

          (g6) Specifically Included Categories of Operating Costs. Subject to
     the Excluded Costs definition, the qualifications on reimbursable Building
     Operating Costs and Complex Operating Costs set forth in Articles 9.1(g1)
     9.1(g2) and 9.1(g3), and

                                      -27-
<PAGE>   36

     except as otherwise expressly excluded from the definition of Building
     Operating Costs and Complex Operating Costs pursuant to the provisions of
     this Lease, Building Operating Costs and Complex Operating Costs shall
     include, but not be limited to, the following, provided that if such costs
     are attributable to the Building and to other buildings in the Complex,
     then such costs shall be equitably apportioned among the Building and such
     other buildings in accordance with Article 9.1(g3), and if such costs are
     attributable to common areas of the Complex and to other property which is
     not part of the Complex, then such costs shall be equitably apportioned
     among the Complex and such other property.

     TAXES (other than Real Estate Taxes): Sales taxes and Federal Social
     Security, Unemployment and Old Age Taxes and contributions and State
     Unemployment taxes and contributions accruing to and paid by the Landlord
     on account of all employees of Landlord and/or Landlord's managing agent,
     who are employed in, about or on account of the Premises (to the extent
     that the underlying wages or salaries are included in Building Operating
     Costs or Complex Operating Costs, as the case may be), except that taxes
     levied upon the net income of the Landlord and taxes withheld from
     employees, and "Taxes" as defined in Article 9.1(d) shall not be included
     herein.

     WATER: All charges and rates connected with water supplied to the Premises,
     the Building and/or the common areas of the Complex and related sewer use
     charges.

     HEAT AND AIR CONDITIONING: The cost of electricity connected with heat and
     air conditioning supplied to the common areas of the Building and/or
     Complex, and all other charges connected with heat and air conditioning
     supplied to the Premises, Building and/or Complex.

     WAGES: Wages and cost of all employee benefits of all employees of the
     Landlord and/or Landlord's managing agent who are employed in, about or on
     account of the Premises and/or Complex provided that wages and costs for
     employees who also work on other properties shall be allocated to the
     Complex based upon the proportion of their time spent working on the
     Complex and then allocated to the Premises on a square foot basis.

     CLEANING: The cost of labor and material for cleaning the Premises and/or
     Complex, surrounding areaways and windows in the Premises and/or Complex,
     including, without limitation, the services listed on Exhibit 4.

     ELEVATOR MAINTENANCE: All expenses for or on account of the upkeep and
     maintenance of all elevators in the Premises, Building and/or the Complex
     (if any).

     ELECTRICITY: The cost of all electric current for the operation of any
     machine, appliance or device used for the operation of the Premises and the
     Building and/or Complex, including the cost of electric current for the
     elevators, lights, air conditioning and heating, but not including electric
     current which is paid for directly to the utility by the user/tenant in the
     Premises and/or Complex. (If and so long as Tenant is billed directly by
     the electric utility for its own consumption of electricity for lights and
     plugs as determined by its separate meter or by submeter, then Operating
     Costs shall include only public area electric current consumption and
     electricity for base building HVAC and not any demised Premises electric
     current consumption for lights and plugs.) Wherever

                                      -28-
<PAGE>   37

     separate metering is unlawful, prohibited by utility company regulation or
     tariff or is otherwise impracticable, relevant consumption figures for the
     purposes of this Article 9 shall be determined by fair and reasonable
     allocations and engineering estimates made by Landlord.

     INSURANCE, ETC.: Fire, casualty, liability and such other insurance as may
     from time to time be reasonably required by lending institutions on
     first-class office buildings in the City or Town wherein the Building is
     located and all other expenses customarily incurred in connection with the
     operation and maintenance of first-class suburban office/research and
     development buildings in the Market Area.

     MANAGEMENT SPACE: Market rate rental costs associated with the Complex's
     management office.

     COMPLEX AMENITIES: The cost of operating any amenities in the Complex
     available to all tenants of the Complex including, without limitation, any
     cafeteria. The costs to be included in Complex Operating Costs shall
     include any subsidy, including lower than market rate rent, provided by
     Landlord for or with respect to such amenity. In the event that the costs
     of a Complex amenity are included in an Operating Year but such costs were
     not included in the Complex Operating Costs Base, then the Complex
     Operating Costs Base shall be adjusted to reflect what would have been the
     costs for such amenity in the Complex Operating Costs Base if such amenity
     had been operated during calendar year 2000.

     9.2  TAX EXCESS.

          (a)  IN GENERAL. Commencing as of the Rent Commencement Date (or, if
there is more than one Rent Commencement Date hereunder, the first such date),
and continuing thereafter throughout the term of this Lease, if with respect to
any Tax Period, the sum ("Tenant's Tax Share") of (i) Tenant's Building Tax
Percentage of Building Taxes plus (ii) Tenant's Complex Tax Percentage of Land
Taxes exceeds the Tax Base, Tenant shall, subject to Article 9.10, pay such
excess to Landlord, such amount being hereinafter referred to as "Tax Excess."
Tax Excess shall be due within thirty (30) days of Tenant's receipt of
Landlord's bill therefor. In implementation and not in limitation of the
foregoing, Tenant shall remit to Landlord pro rata monthly installments on
account of projected Tax Excess, calculated by Landlord on the basis of the most
recent Tax data available. If the total of such monthly remittances on account
of any Tax Period is greater than the actual Tax Excess for such Tax Period,
Tenant may credit the difference against the next installment of rental or other
charges due to Landlord hereunder, except that if such difference is determined
after the end of the term of this Lease, Landlord shall refund such difference
to Tenant within thirty (30) days after such determination to the extent that
such difference exceeds any amounts then due from Tenant to Landlord. If the
total of such remittances is less than the actual Tax Excess for such Tax
Period, Tenant shall pa