<PAGE>



                                LEASE AGREEMENT

                                    between

                       125 SUMMER STREET CORNERSTONE LLC

                                 as "Landlord"

                                      and

                       C-BRIDGE INTERNET SOLUTIONS, INC.


                                  as "Tenant"
<PAGE>

                               TABLE OF CONTENTS
                               -----------------
<TABLE>
<CAPTION>
                                                                        Page
                                                                        ----
<S>                                                                     <C>
1.   PREMISES...........................................................   1
2.   TERM; POSSESSION...................................................   1
3.   RENT...............................................................   1
4.   SECURITY DEPOSIT...................................................   6
5.   USE AND COMPLIANCE WITH LAWS.......................................   7
6.   TENANT IMPROVEMENTS & ALTERATIONS..................................   9
7.   MAINTENANCE AND REPAIRS............................................  10
8.   TENANT'S TAXES.....................................................  12
9.   UTILITIES AND SERVICES.............................................  12
10.  EXCULPATION AND INDEMNIFICATION....................................  14
11.  INSURANCE..........................................................  15
12.  DAMAGE OR DESTRUCTION..............................................  17
13.  CONDEMNATION.......................................................  18
14.  ASSIGNMENT AND SUBLETTING..........................................  20
15.  DEFAULT AND REMEDIES...............................................  20
16.  LATE CHARGE AND INTEREST...........................................  26
17.  WAIVER.............................................................  27
18.  ENTRY, INSPECTION AND CLOSURE......................................  27
19.  SURRENDER AND HOLDING OVER.........................................  28
20.  ENCUMBRANCES.......................................................  29
21.  ESTOPPEL CERTIFICATES AND FINANCIAL STATEMENTS.....................  29
22.  NOTICES............................................................  30
23.  ATTORNEYS' FEES....................................................  30
24.  QUIET POSSESSION...................................................  31
25.  SECURITY MEASURES..................................................  31
26.  FORCE MAJEURE......................................................  31
27.  RULES AND REGULATIONS..............................................  31
28.  LANDLORD'S LIABILITY...............................................  32
29.  CONSENTS AND APPROVALS.............................................  32
30.  WAIVER OF RIGHT TO JURY TRIAL......................................  32
31.  BROKERS............................................................  32
32.  RELOCATION OF PREMISES.............................................  33
33.  ENTIRE AGREEMENT...................................................  33
34.  MISCELLANEOUS......................................................  33
35.  AUTHORITY..........................................................  34
36.  VACANCY DURING LAST SIX MONTHS.....................................  35
</TABLE>

                                       i
<PAGE>

                             INDEX OF DEFINED TERMS
                             ----------------------
<TABLE>
<CAPTION>
                                                                        Page
                                                                        ----
<S>                                                                     <C>
Additional Rent........................................................   4
Alterations............................................................   8
Award..................................................................  16
Base Operating Costs...................................................   2
Base Rent..............................................................   1
Base Taxes.............................................................   2
Broker.................................................................  27
Building...............................................................   1
Building Rules.........................................................  26
Building Systems.......................................................   6
Business Days..........................................................  11
Business Hours.........................................................  11
Commencement Date......................................................   1
Condemnation...........................................................  16
Condemnor..............................................................  16
Construction Rider.....................................................   1
Controls...............................................................  10
Date of Condemnation...................................................  16
Encumbrance............................................................  23
Environmental Losses...................................................   6
Environmental Requirements.............................................   6
Event of Default.......................................................  19
Expiration Date........................................................   1
Fees...................................................................  25
Handled by Tenant......................................................   6
Handling by Tenant.....................................................   6
Hazardous Materials....................................................   6
HVAC...................................................................   6
Interest Rate..........................................................  21
Landlord...............................................................   1
Laws...................................................................   2
Mortgagee..............................................................  24
Operating Costs........................................................   2
Parking Facility.......................................................   1
Permitted Hazardous Materials..........................................   7
Premises...............................................................   1
Project................................................................   1
Property...............................................................   1
Property Manager.......................................................  13
Proposed Transferee....................................................  17
Rent...................................................................   5
</TABLE>

                                      ii
<PAGE>

<TABLE>
<S>                                                                      <C>
Rental Tax.............................................................  10
Representatives........................................................   6
Scheduled Commencement Date............................................   1
Security Deposit.......................................................   5
Service Failure........................................................  11
Substantially Completed................................................   1
Taxes..................................................................   3
Tenant.................................................................   1
Tenant's Share.........................................................   3
Tenant's Taxes.........................................................  10
Tenant Delay...........................................................   1
Tenant Improvements....................................................   8
Term...................................................................   1
Trade Fixtures.........................................................   9
Transfer...............................................................  17
Transferee.............................................................  18
Visitors...............................................................   6
</TABLE>

                                      iii
<PAGE>

                            BASIC LEASE INFORMATION
                            -----------------------

Lease Date:              For identification purposes only, the date
                         of this Lease is March 24, 2000

Landlord:                125 Summer Street Cornerstone LLC, a
                         Delaware limited liability company

Tenant:                  C-Bridge Internet Solutions, Inc., a
                         Delaware corporation

Project:                 125 Summer Street

Building Address:        125 Summer Street, Boston, MA 02110

Rentable Area of         463,691 rentable square feet
Building:

Premises:                Floor:         19
                         Suite Number:  Not Applicable.
                         Rentable Area: 19,682 rentable square feet

Term:                    84 full calendar months (plus any partial
                         month at the beginning of the Term)

Scheduled                June 15, 2000
Commencement Date:

Expiration Date:         The last day of the seventh (7/th/) Lease Year.
                         The term "Lease Year" shall mean
                         any twelve (12) calendar month period
                         commencing on the Term Commencement Date or
                         on any anniversary thereof (plus any partial
                         month at the end of the Term).

Base Rent:               $46.00 PSF of Rentable Area in the Premises
                         for Lease Year 1 through Lease Year 3;

                         $48.00 PSF of Rentable Area in the Premises
                         for Lease Year 4; and

                         $50.00 PSF of Rentable Area in the Premises
                         for Lease Year 5 through Lease Year 7

Base Year                Calendar year 1999 for Operating Costs

                         Fiscal year 2000 for Taxes

                                       1
<PAGE>

Tenant's Share:                See Section 3.2(a)

Security Deposit:              $150,895.00, plus Letter of Credit pursuant
                               to Exhibit E

Landlord's Address for         125 Summer Street Cornerstone LLC
Payment of Rent:               P.O. Box 35334
                               Newark Post Office
                               Newark, NJ 07193-5334

Business Hours:                8:00 A.M. to 6:00 P.M.

Landlord's Address for         125 Summer Street Cornerstone LLC
Notices:                       c/o Cornerstone Properties, Inc.
                               125 Summer Street
                               Boston, MA 02110


                               with a copy to:

                               Wilson Cornerstone Properties
                               2929 Campus Drive, 4th Floor
                               San Mateo, CA 94403
                               Attention:  General Counsel

Tenant's Address for           C-Bridge Internet Solutions, Inc.
Notices:                       219 Vassar Street
                               Cambridge, MA 02139

Access Card Deposit:           $25 per card

Broker(s):                     Meredith & Grew, Inc. and Grubb & Ellis
                               Company

Guarantor(s):                  None.

Property Manager:              Cornerstone Properties, Inc.
                               or such other manager as Landlord may from
                               time to time designate

Additional Provisions:         See Exhibit E

                               1.    Parking

                               2.    Extension Option

                               3.    Right of First Offer

                               4.    Letter of Credit

                                       2
<PAGE>

Exhibits:
--------

Exhibit A:     The Premises
Exhibit B:     Construction Rider
Exhibit C:     Building Rules
Exhibit D:     Landlord Services
Exhibit E:     Additional Provisions
Exhibit F:     Form of Letter of Credit

     The Basic Lease Information set forth above is part of the Lease. In the
event of any conflict between any provision in the Basic Lease Information and
the Lease, the Lease shall control.

                                       3
<PAGE>

     THIS LEASE is made as of the Lease Date set forth in the Basic Lease
Information, by and between the Landlord identified in the Basic Lease
Information ("Landlord"), and the Tenant identified in the Basic Lease
Information ("Tenant"). Landlord and Tenant hereby agree as follows:

1.   PREMISES. Landlord hereby leases to Tenant, and Tenant hereby leases from
Landlord, upon the terms and subject to the conditions of this Lease, the office
space identified in the Basic Lease Information as the Premises (the
"Premises"), in the Building located at the address specified in the Basic Lease
Information (the "Building"). The approximate configuration and location of the
Premises is shown on Exhibit A. Landlord and Tenant agree that the rentable area
                     ---------
of the Premises for all purposes under this Lease shall be the Rentable Area
specified in the Basic Lease Information. The Building, together with the
parking facilities serving the Building (the "Parking Facility"), and the
parcel(s) of land on which the Building and the Parking Facility are situated
(collectively, the "Property"), is part of the Project identified in the Basic
Lease Information (the "Project").

2.   TERM; POSSESSION. The term of this Lease (the "Term") shall commence on the
Commencement Date as described below and, unless sooner terminated, shall expire
on the Expiration Date set forth in the Basic Lease Information (the "Expiration
Date"). The "Commencement Date" shall be the earlier of (a) the date on which
Landlord tenders possession of the Premises to Tenant, with all of Landlord's
construction obligations, if any, "Substantially Completed" as provided in the
Construction Rider attached as Exhibit B (the "Construction Rider") or, in the
                               ---------
event of any "Tenant Delay," as defined in the Construction Rider, the date on
which Landlord could have done so had there been no such Tenant Delay; or (b)
the date upon which Tenant, with Landlord's written permission, actually
occupies and conducts business in any portion of the Premises. The parties
anticipate that the Commencement Date will occur on or about the Scheduled
Commencement Date set forth in the Basic Lease Information (the "Scheduled
Commencement Date"); provided, however, that Landlord shall not be liable for
any claims, damages or liabilities if the Premises are not ready for occupancy
by the Scheduled Commencement Date. When the Commencement Date has been
established, Landlord and Tenant shall at the request of either party confirm
the Commencement Date and Expiration Date in writing.

3.   RENT.

     3.1. Base Rent. Tenant agrees to pay to Landlord the Base Rent set forth in
          ---------
the Basic Lease Information (the "Base Rent"), without prior notice or demand,
in equal monthly installments on the first day of each and every calendar month
during the Term, except that Base Rent for the first full calendar month in
which Base Rent is payable shall be paid upon Tenant's execution of this Lease
and Base Rent for any partial month at the beginning of the Term shall be paid
on the Commencement Date. Base Rent for any partial month at the beginning or
end of the Term shall be prorated based on the actual number of days in the
month.

     If the Basic Lease Information provides for any change in Base Rent by
reference to years or months (without specifying particular dates), the change
will take effect on the applicable annual

                                       1
<PAGE>

or monthly  anniversary of the Commencement  Date (which will not necessarily be
the first day of a calendar month).

     3.2. Additional Rent: Increases in Operating Costs and Taxes.
          -------------------------------------------------------

          (a)  Definitions.
               -----------

               (1)  "Base Operating Costs" means Operating Costs for the
calendar year specified in the Basic Lease Information.

               (2)  "Base Taxes" means Taxes for the fiscal year specified in
 the Basic Lease Information.

               (3)  "Operating Costs" means all costs of managing, operating,
maintaining and repairing the Property, including all costs, expenditures, fees
and charges for: (A) operation, maintenance and repair of the Property
(including maintenance, repair and replacement of glass, the roof covering or
membrane, and landscaping); (B) utilities and services (including
telecommunications facilities and equipment, recycling programs, trash removal,
and snow and ice removal), and associated supplies and materials; (C)
compensation (including employment taxes and fringe benefits) for persons who
perform duties in connection with the operation, management, maintenance and
repair of the Building, such compensation to be appropriately allocated for
persons who also perform duties unrelated to the Building; (D) property
(including coverage for earthquake and flood if carried by Landlord), liability,
rental income and other insurance relating to the Property, and expenditures for
commercially reasonable deductible amounts paid under such insurance; (E)
licenses, permits and inspections; (F) complying with the requirements of any
law, statute, ordinance or governmental rule or regulation or any orders
pursuant thereto (individually a "Law" and collectively "Laws"); (G)
amortization of capital improvements required to comply with Laws, or which are
intended to reduce Operating Costs or improve the utility, efficiency or
capacity of any Building System, with interest on the unamortized balance at the
rate paid by Landlord on funds borrowed to finance such capital improvements
(or, if Landlord finances such improvements out of Landlord's funds without
borrowing, the rate that Landlord would have paid to borrow such funds, as
reasonably determined by Landlord), over such useful life (or, if Landlord so
elects, over such shorter period during which the cost savings resulting from
the capital improvement equal the total cost of the improvement) as Landlord
shall reasonably determine; (H) an office in the Project for the management of
the Property, including expenses of furnishing and equipping such office and the
rental value of any space occupied for such purposes; (I) property management
fees; (J) accounting, legal and other professional services incurred in
connection with the operation of the Property and the calculation of Operating
Costs and Taxes; (K) a reasonable allowance for depreciation on machinery and
equipment used to maintain the Property and on other personal property owned by
Landlord in the Property (including window coverings and carpeting in common
areas); (L) contesting the validity or applicability of any Laws that may affect
the Property; (M) the Building's share of any shared or common area maintenance
fees and expenses (including costs and expenses of operating, managing, owning
and maintaining the Parking Facility and the common areas of the Project and
amenities serving tenants generally); and (N) any other cost, expenditure, fee
or charge, whether or not hereinbefore

                                       2
<PAGE>

described,  which in accordance  with  generally  accepted  property  management
practices would be considered an expense of managing, operating, maintaining and
repairing  the  Property.  Operating  Costs for any  calendar  year during which
average  occupancy of the Building is less than one hundred percent (100%) shall
be calculated  based upon the  Operating  Costs that would have been incurred if
the Building had an average  occupancy of one hundred  percent (100%) during the
entire calendar year.

Notwithstanding the foregoing, Operating Costs shall not include (i) capital
improvements (except as otherwise provided above); (ii) costs of special
services rendered to individual tenants (including Tenant) for which a special
charge is made; (iii) interest, principal payments, points and fees on loans or
indebtedness secured by the Building; (iv) costs of improvements for Tenant or
other tenants of the Building; (v) costs of services or other benefits of a type
which are not available to Tenant but which are available to other tenants or
occupants, and costs for which Landlord is reimbursed by other tenants of the
Building (e.g., tenant electricity) other than through payment of tenants'
shares of increases in Operating Costs and Taxes; (vi) leasing commissions,
advertising costs, attorneys' fees and other expenses incurred in connection
with leasing space in the Building or enforcing such leases; (vii) depreciation
or amortization, other than as specifically enumerated in the definition of
Operating Costs above; (viii) costs, fines or penalties incurred due to
Landlord's violation of any Law; (ix) any costs or expenses incurred by Landlord
in the original construction and development of the Building; (x) costs required
to remedy any noncompliance, as of the date hereof, of the Building with
applicable Law (including, without limitation, the Americans with Disabilities
Act of 1990); (xi) costs relating to maintaining Landlord's existence as a
corporation, limited partnership or other entity; (xii) ground lease payments,
and any other costs related to ground leases; (xiii) any bad debt loss, rent
loss, or reserves for bad debt or rent loss; (xiv) interest or penalties
incurred as a result of Landlord's negligence, willful misconduct or breach of
contract; (xv) salaries of executives or principals of Landlord above the level
of senior property manager (except to the extent the same may be reflected in
any management or building services fee for the Project or attributable to
actual Project management or operations); (xvi) the day-to-day expenses of
cleaning, operating, and maintaining the Parking Facility; (xvii) costs incurred
by Landlord for the repair of damage to the Building, to the extent Landlord is
reimbursed by insurance proceeds; and (xviii) any charitable or political
contributions by Landlord;.

                    (4)  "Taxes" means all taxes, assessments, betterments,
excises, user fees and all other governmental charges and fees of any kind or
nature, or impositions or agreed payments in lieu thereof or voluntary payments
made in connection with the provision of governmental services or improvements
of benefit to the Property (including any so-called linkage, impact or voluntary
betterment payments), and all penalties and interest thereon (if due to Tenant's
failure to make timely payments on account of Taxes), assessed or imposed
against the Premises or the Property of which the Premises are a part (including
without limitation any personal property taxes levied on such Property or on
fixtures or equipment used in connection therewith), or upon Landlord by virtue
of its ownership thereof, other than a federal or state income tax of general
application. If during the Term the present system of ad valorem taxation of
property shall be changed so that, in lieu of or in addition to the whole or any
part of such ad valorem tax, there shall be assessed, levied or imposed on such
Property or Premises or on Landlord any kind or nature of

                                       3
<PAGE>

federal, state, county, municipal or other governmental capital levy, income,
sales, franchise, excise or similar tax, assessment, levy, charge or fee (as
distinct from the federal and state income tax in effect on the Commencement
Date) measured by or based in whole or in part upon Property valuation, mortgage
valuation, rents or any other incidents, benefits or measures of real property
or real property operations, then any and all of such taxes, assessments,
levies, charges and fees (to the extent levied, assessed or imposed with respect
to the Property) shall be included within the term Taxes. For all real estate
taxes (other than assessments payable in installments, for which Taxes for the
year shall include the installments and any applicable interest due and payable
during such year), Taxes for the year shall, at Landlord's election, include
either the amount accrued, assessed, or imposed for such year or the amount due
and payable for that year, provided that such determination of Taxes shall be
applied consistently to Tenant throughout the Term. Taxes also include
reasonable expenses, including fees of attorneys, appraisers and other
consultants, incurred in connection with any efforts to obtain abatements or
reductions or to assure maintenance of Taxes for any tax fiscal year wholly or
partially included in the Term, whether or not successful and whether or not
such efforts involve filing of actual abatement applications or initiation of
formal proceedings.

                    (5)  "Tenant's Share" means the Rentable Area of the
Premises divided by ninety-five percent (95%) of the total Rentable Area of the
Building (or, if greater, the Rentable Area of the Building occupied), as set
forth in the Basic Lease Information. If the Rentable Area of the Building is
changed or the Rentable Area of the Premises is changed by Tenant's leasing of
additional space hereunder or for any other reason, Tenant's Share shall be
adjusted accordingly.

               (b)  Additional Rent.
                    ---------------

                    (1)  Tenant shall pay Landlord as "Additional Rent" for each
calendar year or portion thereof during the Term Tenant's Share of the sum of
(x) the amount (if any) by which Operating Costs for such period exceed Base
Operating Costs, and (y) the amount (if any) by which Taxes for such period
exceed Base Taxes.

                    (2)  Prior to the end of each calendar year, Landlord shall
notify Tenant of Landlord's good faith estimate of Operating Costs, Taxes and
Tenant's Additional Rent for the following calendar year. Commencing on the
first day of January of each calendar year and continuing on the first day of
every month thereafter in such year, Tenant shall pay to Landlord one-twelfth
(1/12th) of the estimated Additional Rent. If Landlord thereafter reasonably
estimates during the course of such calendar year that Operating Costs or Taxes
for such year will vary from Landlord's prior estimate, Landlord may, by notice
to Tenant, revise the estimate for such year (and Additional Rent shall
thereafter be payable based on the revised estimate).

                    (3)  As soon as reasonably practicable after the end of each
calendar year, Landlord shall furnish Tenant a statement with respect to such
year, showing Operating Costs, Taxes and Additional Rent for the year, and the
total payments made by Tenant with respect thereto. Unless Tenant gives notice
of any objections to Landlord's statement within six (6) months after receipt of
the same, such statement shall conclusively be deemed correct and Tenant shall
have no right thereafter to dispute such statement or any item therein or the
computation of

                                       4
<PAGE>

Additional Rent based thereon. If Tenant does object to such statement, then
Landlord shall provide Tenant with reasonable verification of the figures shown
on the statement and the parties shall negotiate in good faith to resolve any
disputes. Any objection of Tenant to Landlord's statement and resolution of any
dispute shall not postpone the time for payment of any amounts due Tenant or
Landlord based on Landlord's statement, nor shall any failure of Landlord to
deliver Landlord's statement in a timely manner relieve Tenant of Tenant's
obligation to pay any amounts due Landlord based on Landlord's statement.

                    (4)  If Tenant's Additional Rent as finally determined for
any calendar year exceeds the total payments made by Tenant on account thereof,
Tenant shall pay Landlord the deficiency within thirty (30) days of Tenant's
receipt of Landlord's statement. If the total payments made by Tenant on account
thereof exceed Tenant's Additional Rent as finally determined for such year,
Tenant's excess payment shall be credited toward the rent next due from Tenant
under this Lease. For any partial calendar year at the beginning or end of the
Term, Additional Rent shall be prorated on the basis of a 365-day year by
computing Tenant's Share of the increases in Operating Costs and Taxes for the
entire year and then prorating such amount for the number of days during such
year included in the Term. Notwithstanding the termination of this Lease,
Landlord shall pay to Tenant or Tenant shall pay to Landlord, as the case may
be, within thirty (30) days after Tenant's receipt of Landlord's final statement
for the calendar year in which this Lease terminates, the difference between
Tenant's Additional Rent for that year, as finally determined by Landlord, and
the total amount previously paid by Tenant on account thereof.

     If for any reason Taxes for any year during the Term are reduced, refunded
or otherwise changed, Tenant's Additional Rent shall be adjusted accordingly. If
Taxes are temporarily reduced as a result of space in the Building being leased
to a tenant that is entitled to an exemption from property taxes or other taxes,
then for purposes of determining Additional Rent for each year in which Taxes
are reduced by any such exemption, Taxes for such year shall be calculated on
the basis of the amount the Taxes for the year would have been in the absence of
the exemption. The obligations of Landlord to refund any overpayment of
Additional Rent and of Tenant to pay any Additional Rent not previously paid
shall survive the expiration of the Term.

                    (5)  Provided that no Event of Default (or condition as to
which Tenant has received notice, which with the passage of time, would
constitute an Event of Default) then exists, Tenant shall have the right to
audit Landlord's annual statement concerning Operating Costs and Taxes for the
year just ended, subject to and in accordance with this Section 3(b)(5). Any
request by Tenant to conduct such an audit shall be made by written notice
delivered to Landlord not later than ninety (90) days after Tenant's receipt of
such annual statement, specifying the items in such annual statement that Tenant
desires to audit. Any such audit shall be conducted by a certified public
accountant from one of the six largest national accounting firms. Before the
commencement of any such audit, Tenant and its accountant shall also enter into
a confidentiality agreement with Landlord, in a form reasonably supplied by
Landlord, certifying that Tenant has not engaged any person or firm on a
contingency fee basis in connection with this audit and agreeing to restrict the
use of all information solely to the determination of Tenant's Proportionate
Share of Operating Cost and Taxes under this Lease. At least ten (10) business
days prior to commencement of the audit, Tenant shall provide Landlord

                                       5
<PAGE>

with a list of requested information. The accountant's field work shall take
place during business hours in the offices of Landlord or its building manager
(or in another location specified by Landlord in Boston, Massachusetts) and
shall be completed within no more than five (5) business days commencing on the
date that such access is first made available to Tenant. Access shall be limited
to the records evidencing the Operating Costs and Taxes allocable to the
Premises that were used by Landlord in preparing such annual statement. Copies
of any documents requested by Tenant shall be made by Landlord at Tenant's
expense. Tenant shall furnish Landlord with a copy of the completed audit report
not later than two (2) months after the date such access is first made available
to Tenant. Any discussions between Landlord and Tenant concerning the results of
the audit shall include authorized representatives of each party. If Landlord
agrees with the results of Tenant's completed audit report, or if the parties do
not so agree but a final judgment is reached that payments made by Tenant are in
excess of the payments properly payable to Landlord hereunder, Landlord shall
refund to Tenant the amount of any such excess payments or credit the amount
toward the rent next due from Tenant under this Lease. If Tenant's audit
discloses that payments made by Tenant are less than the payments properly
payable to Landlord hereunder, Tenant shall pay to Landlord the amount of any
such underpayments. If such audit reveals that Landlord's annual statement has
overstated Operating Costs by more than five percent (5%), Landlord shall
reimburse Tenant for the reasonable third-party costs incurred by Tenant's
auditor in conducting the audit. If Tenant fails timely to request an audit or
to provide Landlord with the completed audit report as set forth above, Tenant
shall be deemed to have accepted the Landlord's annual statement for the year
just ended. The rights granted under this Section 3(b)(5) are personal to the
Tenant originally named herein (and any permitted Successor or Affiliate to whom
this Lease is assigned under Section 14.2(c)) and may not be exercised by or on
behalf of any subtenant or other party.

     3.3. Payment of Rent. All amounts payable or reimbursable by Tenant under
          ---------------
this Lease, including late charges and interest (collectively, "Rent"), shall
constitute rent and shall be payable and recoverable as rent in the manner
provided in this Lease. All sums payable to Landlord on demand under the terms
of this Lease shall be payable within thirty (30) days after notice from
Landlord of the amounts due. All rent shall be paid without offset, recoupment
or deduction in lawful money of the United States of America to Landlord at
Landlord's Address for Payment of Rent as set forth in the Basic Lease
Information, or to such other person or at such other place as Landlord may from
time to time designate.

4.   SECURITY DEPOSIT. On execution of this Lease, Tenant shall deposit with
Landlord the amount specified in the Basic Lease Information as the Security
Deposit, if any (the "Security Deposit"), as security for the performance of
Tenant's obligations under this Lease. Landlord may (but shall have no
obligation to) use the Security Deposit or any portion thereof to cure any Event
of Default under this Lease or to compensate Landlord for any damage Landlord
incurs as a result of Tenant's failure to perform any of Tenant's obligations
hereunder. In such event Tenant shall pay to Landlord on demand an amount
sufficient to replenish the Security Deposit. If Tenant is not in default at the
expiration or termination of this Lease, Landlord shall return to Tenant the
Security Deposit or the balance thereof then held by Landlord and not applied as
provided above. Landlord may commingle the Security Deposit with Landlord's
general and other funds. Landlord shall not be required to pay interest on the
Security Deposit to Tenant.

                                       6
<PAGE>

5.   USE AND COMPLIANCE WITH LAWS.

     5.1. Use. The Premises shall be used and occupied for general business
          ---
office purposes and for no other use or purpose. Tenant shall comply with all
present and future Laws relating to Tenant's use or occupancy of the Premises
(and make any repairs, alterations or improvements as required to comply with
all such Laws), and shall observe the "Building Rules" (as defined in Section
27 -Rules and Regulations). Tenant shall not do, bring, keep or sell anything in
or about the Premises that is prohibited by, or that will cause a cancellation
of or an increase in the existing premium for, any insurance policy covering the
Property or any part thereof. Tenant shall not permit the Premises to be
occupied or used in any manner that will constitute waste or a nuisance, or
disturb the quiet enjoyment of or otherwise annoy other tenants in the Building.
Without limiting the foregoing, the Premises shall not be used for educational
activities (other than business programs designed for Tenant's employees or
customers), practice of medicine or any of the healing arts, providing social
services, for any governmental use (including embassy or consulate use), or for
personnel agency, customer service office open to the general public, studios
for radio, television or other media, travel agency or reservation center
operations or uses. Tenant shall not, without the prior consent of Landlord, (i)
bring into the Building or the Premises anything that may cause substantial
noise, odor or vibration, overload the floors in the Premises or the Building or
any of the heating, ventilating and air-conditioning ("HVAC"), mechanical,
elevator, plumbing, electrical, fire protection, life safety, security or other
systems in the Building ("Building Systems"), or jeopardize the structural
integrity of the Building or any part thereof; (ii) connect to the utility
systems of the Building any apparatus, machinery or other equipment other than
typical office equipment; or (iii) connect to any electrical circuit in the
Premises any equipment or other load with aggregate electrical power
requirements in excess of 80% of the rated capacity of the circuit.

     5.2. Hazardous Materials.
          -------------------

          (a)  Definitions.
               -----------

               (1)  "Hazardous Materials" shall mean any substance: (A) that now
or in the future is regulated by, or is defined as a hazardous substance,
pollutant or contaminant under, any governmental law, including the
Comprehensive Environmental Response Compensation and Liability Act, 42 U.S.C.
(S) 9601 et seq., and the Resource Conservation and Recovery Act, 42 U.S.C. (S)
         -- ---
6901 et seq., and any oil or hazardous substance or material regulated under the
     -- ---
Massachusetts Hazardous Waste Management Act, as amended, M.G.L. Chapter 21C,
and the Massachusetts Oil and Hazardous Material Release Prevention Act, as
amended, M.G.L. Chapter 21E, and the regulations adopted under these acts, or
(B) that is toxic, dangerous or otherwise hazardous, including gasoline, diesel
fuel, petroleum hydrocarbons, polychlorinated biphenyls (PCBs), asbestos, radon
and urea formaldehyde foam insulation.

               (2)  "Environmental Requirements" shall mean all present and
future Laws, approvals, and other requirements of any kind applicable to
Hazardous Materials.

               (3)  "Handled by Tenant" and "Handling by Tenant" shall mean and
refer to any storage, use, disposal, transportation, or any other activity of
any type by Tenant or its

                                       7
<PAGE>

agents, employees, contractors, licensees, assignees, sublessees, transferees or
representatives (collectively, "Representatives") or its guests, customers,
invitees, or visitors (collectively, "Visitors"), at or about the Premises or
Property in connection with or involving Hazardous Materials.

               (4)  "Environmental Losses" shall mean all costs and expenses of
any kind, damages, fines and penalties incurred in connection with any violation
of and compliance with Environmental Requirements and all losses of any kind
attributable to the diminution of value, loss of use or adverse effects on any
portion of the Premises or Property.

               (5)  "Claims" shall mean all claims, actions, losses, damages,
liabilities, costs and expenses of every kind, including reasonable attorneys',
experts' and consultants' fees and costs.

          (b)  Tenant's Covenants. No Hazardous Materials shall be Handled by
               ------------------
Tenant without Landlord's prior written consent, which consent may be withheld
or conditioned in Landlord's absolute discretion. Notwithstanding the foregoing,
normal quantities and use of those Hazardous Materials customarily used in the
conduct of general office activities, such as copier fluids and cleaning
supplies ("Permitted Hazardous Materials"), may be used and stored at the
Premises without Landlord's prior written consent, provided that such activities
of Tenant shall comply at all times with all Environmental Requirements. At the
expiration or termination of the Lease, Tenant shall promptly remove from the
Premises and Property all Hazardous Materials Handled by Tenant. Tenant shall be
responsible and liable for the compliance with all of the provisions of this
Section by all of Tenant's Representatives and Visitors, and all of Tenant's
obligations under this Section (including its indemnification obligations under
subsection (e) below) shall survive the expiration or termination of this Lease.

          (c)  Compliance. Tenant shall at Tenant's expense promptly take all
               ----------
actions required by any governmental agency or entity in connection with or as a
result of the Handling by Tenant of Hazardous Materials. All of the foregoing
work and all Handling by Tenant of all Hazardous Materials shall be performed in
a good, safe and workmanlike manner by consultants qualified and licensed to
undertake such work and in a manner that will not interfere with any other
tenant's quiet enjoyment of the Property or Landlord's use, operation, leasing
and sale of the Property.

          (d)  Landlord's Rights. Landlord shall have the right, but not the
               -----------------
obligation, to enter the Premises at any reasonable time and (except in cases of
emergency) upon reasonable prior notice (i) to confirm Tenant's compliance with
the provisions of this Section 5.2, and (ii) to perform Tenant's obligations
under this Section if Tenant has failed to do so after reasonable notice to
Tenant. Tenant shall pay to Landlord on demand the costs of Landlord's
consultants' fees and all costs incurred by Landlord in performing Tenant's
obligations under this Section.

          (e)  Tenant's Indemnification. Tenant agrees to indemnify, defend,
               ------------------------
protect and hold harmless Landlord and its partners or members and its or their
partners, members, directors, officers, shareholders, employees and agents from
all Environmental Losses and all other Claims incurred at any time and arising
from or in connection with the Handling by Tenant of Hazardous

                                       8
<PAGE>

Materials or Tenant's failure to comply in full with all Environmental
Requirements with respect to the Premises.

     5.3. Landlord represents that, to the best of Landlord's knowledge as of
the date hereof, the Premises do not contain any materials known as of the date
hereof to be Hazardous Materials that materially adversely affect Tenant's use
of the Premises for the permitted uses under Section 5.1.

6.   TENANT IMPROVEMENTS & ALTERATIONS.

     6.1  Landlord and Tenant shall perform their respective obligations with
respect to design and construction of any improvements to be constructed and
installed in the Premises (the "Tenant Improvements"), as provided in the
Construction Rider. Except for any Tenant Improvements to be constructed by
Landlord for Tenant as provided in the Construction Rider, Tenant shall not make
any alterations, improvements or changes to the Premises, including installation
of any security system or telephone or data communication wiring
("Alterations"), without Landlord's prior written consent, which consent shall
not be unreasonably withheld or delayed provided that the proposed Alterations
comply with the provisions of this Section 6 and this Lease. (Notwithstanding
the foregoing, any nonstructural Alterations within the Premises that do not
affect any mechanical, electrical, or other Building systems, do not cost more
than $10,000 in the aggregate, and do not adversely affect the value of the
Premises for general office uses shall not require Landlord's prior approval,
provided that Tenant shall give Landlord notice of the commencement of such work
(including plans and specifications therefor, as provided below) at least ten
(10) days in advance and the work otherwise complies with the provisions of this
Section 6 and this Lease.) Any such Alterations shall be completed by Tenant at
Tenant's sole cost and expense: (i) with due diligence, in a good and
workmanlike manner, using new materials; (ii) in compliance with plans and
specifications approved by Landlord; (iii) in compliance with the non-
discriminatory construction rules and regulations promulgated by Landlord from
time to time; (iv) in accordance with all applicable Laws (including all work,
whether structural or non-structural, inside or outside the Premises, required
to comply fully with all applicable Laws and necessitated by Tenant's work); and
(v) subject to all conditions which Landlord may in Landlord's reasonable
discretion impose. Such conditions may include requirements for Tenant to: (i)
provide payment or performance bonds or additional insurance (from Tenant or
Tenant's contractors, subcontractors or design professionals); (ii) use
contractors or subcontractors designated by Landlord; and (iii) remove all or
part of the Alterations prior to or upon expiration or termination of the Term,
as designated by Landlord. If any work outside the Premises, or any work on or
adjustment to any of the Building Systems, is required in connection with or as
a result of Tenant's work, such work shall be performed at Tenant's expense by
contractors designated by Landlord. Landlord's right to review and approve (or
withhold approval of) Tenant's plans, drawings, specifications, contractor(s)
and other aspects of construction work proposed by Tenant is intended solely to
protect Landlord, the Property and Landlord's interests. No approval or consent
by Landlord shall be deemed or construed to be a representation or warranty by
Landlord as to the adequacy, sufficiency, fitness or suitability thereof or
compliance thereof with applicable Laws or other requirements. Except as
otherwise provided in Landlord's consent, all Alterations shall upon
installation become part of the realty and be the property of Landlord.

                                       9
<PAGE>

     If Tenant specifically requests at the time of its submission of proposed
plans to Landlord by written notice bearing the legend "Request for Confirmation
of Restoration Obligations," Landlord shall identify the elements (if any) of
the proposed Alterations that Landlord may require Tenant to remove at the end
of the Term, provided that Tenant shall not be required to remove Alterations
that are standard for general office use of the Premises and do not increase the
costs of demolishing space for another tenant. Landlord shall have the right to
require Tenant to remove any internal stairs, cafeteria, raised floors, demising
walls for subtenants, vaults, and private bathrooms installed by or for Tenant.

     6.2  Before making any Alterations, Tenant shall submit to Landlord for
Landlord's prior approval reasonably detailed final plans and specifications
prepared by a licensed architect or engineer, a copy of the construction
contract, including the name of the contractor and all subcontractors proposed
by Tenant to make the Alterations and a copy of the contractor's license. Tenant
shall reimburse Landlord upon demand for any expenses reasonably incurred by
Landlord in connection with any Alterations made by Tenant, including reasonable
fees charged by Landlord's contractors or consultants to review plans and
specifications prepared by Tenant and to update the existing as-built plans and
specifications of the Building to reflect the Alterations. Tenant shall obtain
all applicable permits, authorizations and governmental approvals and deliver
copies of the same to Landlord before commencement of any Alterations.

     6.3  Tenant shall keep the Premises and the Property free and clear of
all liens arising out of any work performed, materials furnished or obligations
incurred by Tenant. If any such lien attaches to the Premises or the Property,
and Tenant does not cause the same to be released by payment, bonding or
otherwise within ten (10) business days after the attachment thereof, Landlord
shall have the right but not the obligation to cause the same to be released,
and any sums expended by Landlord (plus Landlord's administrative costs) in
connection therewith shall be payable by Tenant on demand with interest thereon
from the date of expenditure by Landlord at the Interest Rate (as defined in
Section 16.2 - Interest). Tenant shall give Landlord at least ten (10) days'
notice prior to the commencement of any Alterations and cooperate with Landlord
in posting and maintaining notices of non-responsibility in connection
therewith.

     6.4  Subject to the provisions of Section 5 - Use and Compliance with
Laws and the foregoing provisions of this Section, Tenant may install and
maintain furnishings, equipment, movable partitions, business equipment and
other trade fixtures ("Trade Fixtures") in the Premises, provided that the Trade
Fixtures do not become an integral part of the Premises or the Building. Tenant
shall promptly repair any damage to the Premises or the Building caused by any
installation or removal of such Trade Fixtures.

7.   MAINTENANCE AND REPAIRS.

     7.1  By taking possession of the Premises Tenant agrees that the
Premises are then in a good and tenantable condition, subject to completion of
punchlist items under Section 1.2 of Exhibit B. Subject to Section 7.2, during
the Term, Tenant at Tenant's expense but under the direction of Landlord, shall
repair and maintain the Premises, including the interior walls, floor coverings,
ceiling (ceiling tiles and grid), Tenant Improvements, Alterations, fire
extinguishers,

                                      10
<PAGE>

outlets and fixtures, and any appliances (including dishwashers, tenant hot
water heaters and garbage disposers) in the Premises, in a first class
condition, and keep the Premises in a clean, safe and orderly condition.

     7.2  Landlord shall maintain or cause to be maintained in reasonably
good order, condition and repair, the structural portions of the roof,
foundations, floors and exterior walls of the Building, the Building Systems,
and the public and common areas of the Property, such as elevators, stairs,
corridors and restrooms; provided, however, that Tenant shall pay the cost of
repairs for any damage occasioned by Tenant's use of the Premises (with the
exception of reasonable wear and tear) or the Property or any act or omission of
Tenant or Tenant's Representatives or Visitors, to the extent (if any) not
covered by Landlord's property insurance. Landlord shall be under no obligation
to inspect the Premises. Tenant shall promptly report in writing to Landlord any
defective condition known to Tenant which Landlord is required to repair. As a
material part of the consideration for this Lease, Tenant hereby waives any
benefits of any applicable existing or future Law, that allows a tenant to make
repairs at its landlord's expense.

     7.3  Landlord hereby reserves the right, at any time and from time to
time, without liability to Tenant, and without constituting an eviction,
constructive or otherwise, or entitling Tenant to any abatement of rent or to
terminate this Lease or otherwise releasing Tenant from any of Tenant's
obligations under this Lease:

          (a) To make alterations, additions, repairs, improvements to or in or
to decrease the size or area of, all or any part of the Building, the fixtures
and equipment therein, and the Building Systems, provided that (except in cases
of emergency) Landlord shall use reasonable efforts to minimize any disruption
of Tenant's use of the Premises;

          (b) To change the Building's name or street address;

          (c) To install and maintain any and all signs on the exterior and
interior of the Building;

          (d) To reduce, increase, enclose or otherwise change at any time and
from time to time the size, number, location, lay-out and nature of the common
areas (including the Parking Facility, provided that such alterations shall not
reduce the number of parking spaces allotted to tenant under Exhibit E hereto
and provided that (except in cases of emergency) Landlord shall use reasonable
efforts to minimize any disruption of Tenant's use of and access to the
Premises) and other tenancies and premises in the Property and to create
additional rentable areas through use or enclosure of common areas; and

          (e) If any governmental authority promulgates or revises any Law or
imposes mandatory or voluntary controls or guidelines on Landlord or the
Property relating to the use or conservation of energy or utilities or the
reduction of automobile or other emissions or reduction or management of traffic
or parking on the Property (collectively "Controls"), to comply with such
Controls, whether mandatory or voluntary, or make any alterations to the
Property related thereto. In connection with the foregoing, Tenant shall
cooperate with Landlord and abide by all Building regulations that Landlord may,
from time to time, prescribe for the proper functioning and

                                      11
<PAGE>

protection of the heating and air-conditioning systems and in order to maximize
the effect thereof and to conserve heat and air-conditioning.

8.   TENANT'S TAXES. "Tenant's Taxes" shall mean (a) all taxes, assessments,
license fees and other governmental charges or impositions levied or assessed
against or with respect to Tenant's personal property or Trade Fixtures in the
Premises, whether any such imposition is levied directly against Tenant or
levied against Landlord or the Property, (b) all rental, excise, sales or
transaction privilege taxes arising out of this Lease (excluding, however, state
and federal personal or corporate income taxes measured by the income of
Landlord from all sources) imposed by any taxing authority upon Landlord or upon
Landlord's receipt of any rent payable by Tenant pursuant to the terms of this
Lease ("Rental Tax"), and (c) any increase in Taxes attributable to inclusion of
a value placed on Tenant's personal property, Trade Fixtures or Alterations.
Tenant shall pay any Rental Tax to Landlord in addition to and at the same time
as Base Rent is payable under this Lease, and shall pay all other Tenant's Taxes
before delinquency (and, at Landlord's request, shall furnish Landlord
satisfactory evidence thereof). If Landlord pays Tenant's Taxes or any portion
thereof, Tenant shall reimburse Landlord upon demand for the amount of such
payment, together with interest at the Interest Rate from the date of Landlord's
payment to the date of Tenant's reimbursement.

9.   UTILITIES AND SERVICES.

     9.1  Description of Services. Landlord shall furnish to the Premises:
          -----------------------
reasonable amounts of water, heat, ventilation and air-conditioning during the
Business Hours specified in the Basic Lease Information ("Business Hours") on
weekdays except public holidays ("Business Days"); reasonable amounts of
electricity; and janitorial services five days a week (except public holidays),
all in accordance with Exhibit D. Any electrical power supply or supplemental
                       ---------
HVAC required as a result of Tenant's particular use of the Premises (above the
Building standard levels for general office use) shall be installed at Tenant's
expense (subject to the tenant improvement allowance under Exhibit B). Landlord
shall also provide the Building with normal fluorescent tube replacement, window
washing, elevator service, and common area toilet room supplies. Any additional
utilities or services that Landlord may agree to provide (including lamp or tube
replacement for other than Building Standard lighting fixtures) shall be at
Tenant's sole expense.

     9.2  Payment for Additional Utilities and Services.
          ---------------------------------------------

          (a)  Upon request by Tenant in accordance with the procedures
established by Landlord from time to time for furnishing HVAC service at times
other than Business Hours on Business Days, Landlord shall furnish such service
to Tenant and Tenant shall pay for such services on an hourly basis at the then
prevailing rate established for the Building by Landlord. The Building's current
prevailing rate is $47 per hour per floor.

          (b)  If the temperature otherwise maintained in any portion of the
Premises by the HVAC systems of the Building is affected as a result of (i) any
lights, machines or equipment used by Tenant in the Premises, or (ii) the
occupancy of the Premises by more than one person per 150 square feet of
rentable area, then Landlord shall have the right to install any machinery or
equipment reasonably necessary to restore the temperature, including
modifications to the standard

                                      12
<PAGE>

air-conditioning equipment. The cost of any such equipment and modifications,
including the cost of installation and any additional cost of operation and
maintenance of the same, shall be paid by Tenant to Landlord upon demand.

          (c)  Tenant shall pay to Landlord all charges for electricity supplied
to the Premises. Tenant's actual consumption of electricity shall be measured by
any separate meter installed for the Premises or, if the Premises are not
separately metered, based on Landlord's reasonable judgment as to the level of
consumption in the Premises. (The initial Premises hereunder are separately
metered.) Landlord reserves the right to discontinue the furnishing of electric
current to the Premises upon not less than two months' notice (or such longer
time as may be required to make arrangements with the electric utility for
direct service provided Tenant exercises its best efforts to complete said
arrangements as soon as possible), whereupon Tenant's obligation to pay
Additional Rent for electricity under this paragraph shall cease. If Landlord so
elects to discontinue electric service, Tenant shall contract directly with the
utility company supplying electric current.

          (d)  If Tenant's usage of water or any other utility service exceeds
the use of such utility Landlord determines to be typical, normal and customary
for the Building, Landlord may determine the amount of such excess use by any
reasonable means (including the installation at Landlord's request but at
Tenant's expense of a separate meter or other measuring device) and charge
Tenant for the cost of such excess usage. In addition, Landlord may impose a
reasonable charge for the use of any additional or unusual janitorial services
required by Tenant because of any unusual Tenant Improvements or Alterations,
the carelessness of Tenant or the nature of Tenant's business (including hours
of operation).

     9.3  Interruption of Services. In the event of an interruption in, or
          ------------------------
failure or inability to provide any of the services or utilities described in
Section 9.1 - "Description of Services" (a "Service Failure"), Landlord shall
use reasonable and diligent efforts, consistent with a first-class office tower
in downtown Boston, to remedy and limit the duration of any such Service
Failure, provided that such Service Failure shall not, regardless of its
duration, constitute an eviction of Tenant, constructive or otherwise, or impose
upon Landlord any liability whatsoever, including, but not limited to, liability
of consequential damages or loss of business by Tenant or, except as provided
herein, entitle Tenant to an abatement of rent or to terminate this Lease.

          (a)  If any Service Failure not caused by Tenant or its
Representatives prevents Tenant from reasonably using a material portion of the
Premises and Tenant in fact ceases to use such portion of the Premises, Tenant
shall be entitled to an abatement of Base Rent and Additional Rent with respect
to the portion of the Premises that Tenant is prevented from using by reason of
such Service Failure in the following circumstances: (i) if the Service Failure
has persisted and continuously prevented Tenant from using a material portion of
the Premises for a period of five (5) consecutive Business Days after Tenant's
notice to Landlord of such Service Failure and such failure is due to Landlord's
negligence or misconduct or other cause within Landlord's control, the abatement
of rent shall commence on the sixth Business Day following notice of the Service
Failure and continue until Tenant is no longer so prevented from using such
portion of the Premises; and (ii) if the Service Failure has persisted for a
period of ten (10) consecutive Business

                                      13
<PAGE>

Days after Tenant's notice to Landlord of such failure and such failure is due
to causes not within Landlord's control and Tenant in fact does not use such
portion of the Premises for such ten (10) consecutive Business Day period or
more by reason of such Service Failure, then to the extent such Service Failure
is covered by Landlord's rental interruption insurance policy the abatement of
rent shall commence no later than the eleventh Business Day following such
notice of the occurrence of the Service Failure and continue until Tenant is no
longer so prevented from using such portion of the Premises. As used in this
paragraph, "Business Day" shall refer only to full Business Days (from 8:00 A.M.
to 6:00 P.M.) commencing on the Business Day next following the Business Day on
which Tenant delivers to Landlord notice of the Service Failure.

          (b)  If a Service Failure is caused by Tenant or its Representatives,
Landlord shall nonetheless remedy the Service Failure, at the expense of Tenant,
pursuant to Landlord's maintenance and repair obligations under Section 7 -
"Maintenance and Repair" or Section 12.1 - "Landlord's Duty to Repair," as the
case may be, but Tenant shall not be entitled to an abatement of rent or to
terminate this Lease as a result of any such Service Failure.

          (c)  Where the cause of a Service Failure is within the control of a
public utility or other public or quasi-public entity outside Landlord's
control, notification to such utility or entity of the Service Failure and
request to remedy the failure shall constitute "reasonable efforts" by Landlord
to remedy the Service Failure.

          (d)  Tenant hereby waives the provisions of any applicable existing or
future law, ordinance or governmental regulation permitting the termination of
this Lease due to such interruption, failure or inability.

          (e)  This Section does not apply to casualty and/or condemnation, as
to which Sections 12 and 13, respectively, apply.

10.  EXCULPATION AND INDEMNIFICATION.

     10.1 Tenant's Indemnification of Landlord. Tenant shall indemnify, protect,
          ------------------------------------
defend and hold Landlord and Landlord's authorized representatives harmless from
and against Claims arising from (a) the acts or omissions of Tenant or Tenant's
Representatives or Visitors in or about the Property, or (b) any construction or
other work undertaken by Tenant on the Premises (including any design defects),
or (c) any breach or default under this Lease by Tenant, or (d) any loss, injury
or damage, howsoever and by whomsoever caused, to any person or property,
occurring in or about the Premises during the Term, excepting only Claims
described in this clause (d) to the extent they are caused by the willful
misconduct or negligent acts or omissions of Landlord or its authorized
representatives.

     10.2 Damage to Tenant and Tenant's Property. To the maximum extent
          --------------------------------------
permitted by law: (a) Landlord shall not be liable to Tenant for any loss,
injury or other damage to Tenant or to Tenant's property in or about the
Premises or the Property from any cause (including defects in the Property or in
any equipment in the Property; fire, explosion or other casualty; bursting,
rupture, leakage or overflow of any plumbing or other pipes or lines,
sprinklers, tanks, drains, drinking fountains or washstands in, above, or about
the Premises or the Property; or acts of other tenants in

                                      14
<PAGE>

the Property); (b) Tenant hereby waives all claims against Landlord for any such
loss, injury or damage and the cost and expense of defending against claims
relating thereto; and (c) notwithstanding any other provision of this Lease to
the contrary, in no event shall either party be liable to the other for any
punitive or consequential damages or damages for loss of business by the other.

     10.3 Landlord Indemnification. Except as may be provided in Sections 9,
          ------------------------
10.2, 12, and 25, and subject to Section 11.3 and the limitations on the
liability of Landlord set forth in this Lease, Landlord shall indemnify and hold
Tenant harmless from and against any claim arising out of any loss, injury or
damage to any person or property occurring in the common areas of the Building
during the Term, to the extent that such loss, injury, or damage results from
the negligence or willful misconduct of Landlord.

     10.4 Survival.  The obligations of the parties under this Section 10 shall
          --------
survive the expiration or termination of this Lease.

11.  INSURANCE.

     11.1 Tenant's Insurance.
          ------------------

          (a) Liability Insurance. Tenant shall maintain in full force
              -------------------
throughout the Term, commercial general liability insurance providing coverage
on an occurrence form basis with limits of not less than Two Million Dollars
($2,000,000.00) each occurrence for bodily injury and property damage combined,
Two Million Dollars ($2,000,000.00) annual general aggregate, and Two Million
Dollars ($2,000,000.00) products and completed operations annual aggregate.
Tenant's liability insurance policy or policies shall: (i) include premises and
operations liability coverage, products and completed operations liability
coverage, broad form property damage coverage including completed operations,
blanket contractual liability coverage including, to the maximum extent
possible, coverage for the indemnification obligations of Tenant under this
Lease, and personal and advertising injury coverage; (ii) provide that the
insurance company has the duty to defend all insureds under the policy; (iii)
provide that defense costs are paid in addition to and do not deplete any of the
policy limits; (iv) cover liabilities arising out of or incurred in connection
with Tenant's use or occupancy of the Premises or the Property; (v) extend
coverage to cover liability for the actions of Tenant's Representatives and
Visitors; and (vi) designate separate limits for the Property. Each policy of
liability insurance required by this Section shall: (1) contain a cross
liability endorsement or separation of insureds clause; (2) provide that any
waiver of subrogation rights or release prior to a loss does not void coverage;
(3) provide that it is primary to and not contributing with, any policy of
insurance carried by Landlord covering the same loss; (4) provide that any
failure to comply with the reporting provisions by Tenant shall not affect
coverage provided to Landlord, its partners, members, managing members,
managers, affiliates, property managers and Mortgagees; and (5) name Landlord,
its partners, members, managing members, managers, affiliates, the Property
Manager identified in the Basic Lease Information (the "Property Manager"), and
such other parties in interest as Landlord may from time to time reasonably
designate to Tenant in writing, as additional insureds. Such additional insureds
shall be provided at least the same extent of coverage as is provided to Tenant
under such policies with

                                      15
<PAGE>

respect to liability arising out of the ownership, maintenance or use of the
Premises. All endorsements effecting such additional insured status shall be at
least as broad as additional insured endorsement form number CG 20 11 11 85 or
CG 20 11 11 01 96 promulgated by the Insurance Services Office or its successor
organization.

          (b)  Property Insurance. Tenant shall at all times maintain in effect
               ------------------
with respect to any Alterations and Tenant's Trade Fixtures and personal
property, commercial property insurance providing coverage, on an "all risk" or
"special form" basis, in an amount equal to at least the full replacement cost
of the covered property. Tenant may carry such insurance under a blanket policy,
provided that such policy provides coverage equivalent to a separate policy.
During the Term, the proceeds from any such policies of insurance shall be used
for the repair or replacement of the Alterations, Trade Fixtures and personal
property so insured. Landlord shall be provided coverage under such insurance to
the extent of its insurable interest and, if requested by Landlord, both
Landlord and Tenant shall sign all documents reasonably necessary or proper in
connection with the settlement of any claim or loss under such insurance.
Landlord will have no obligation to carry insurance on any Alterations or on
Tenant's Trade Fixtures or personal property.

          (c)  Requirements For All Policies. Each policy of insurance
               -----------------------------
required under this Section 11.1 shall: (i) be in a form, and written by an
insurer, reasonably acceptable to Landlord, (ii) be maintained at Tenant's sole
cost and expense, and (iii) require at least thirty (30) days' written notice to
Landlord prior to any cancellation, nonrenewal or modification of insurance
coverage. Insurance companies issuing such policies shall have rating
classifications of "A" or better and financial size category ratings of "VII" or
better according to the latest edition of the A.M. Best Key Rating Guide. All
insurance companies issuing such policies shall be admitted carriers licensed to
do business in the state where the Property is located. Any deductible amount
under such insurance shall not exceed $5,000. Tenant shall provide to Landlord,
upon request, evidence that the insurance required to be carried by Tenant
pursuant to this Section, including any endorsement effecting the additional
insured status, is in full force and effect and that premiums therefor have been
paid.

          (d)  Updating Coverage. Tenant shall increase the amounts of insurance
               -----------------
as required by any Mortgagee, and, not more frequently than once every three (3)
years, as recommended by Landlord's insurance broker, if, in the opinion of
either of them, the amount of insurance then required under this Lease is not
adequate. Any limits set forth in this Lease on the amount or type of coverage
required by Tenant's insurance shall not limit the liability of Tenant under
this Lease.

          (e)  Certificates of Insurance. Prior to occupancy of the Premises by
               -------------------------
Tenant, and not less than thirty (30) days prior to expiration of any policy
thereafter, Tenant shall furnish to Landlord a certificate of insurance
reflecting that the insurance required by this Section is in force, accompanied
by an endorsement showing the required additional insureds satisfactory to
Landlord in substance and form. Notwithstanding the requirements of this
paragraph, if requested by Landlord's Mortgagee or if reasonably required by
Landlord to confirm Tenant's compliance herewith or to exercise rights as an
additional insured, Tenant shall at Landlord's request provide to

                                      16
<PAGE>

Landlord a certified copy of each insurance policy required to be in force at
any time pursuant to the requirements of this Lease or its Exhibits.

     11.2 Landlord's Insurance. During the Term, to the extent such coverages
          --------------------
are available at a commercially reasonable cost, Landlord shall maintain in
effect insurance on the Building with responsible insurers, on an "all risk" or
"special form" basis, insuring the Building and the Tenant Improvements in an
amount equal to at least 90% of the replacement cost thereof, excluding land,
foundations, footings and underground installations. Landlord may, but shall not
be obligated to, carry insurance against additional perils and/or in greater
amounts.

     11.3 Mutual Waiver of Right of Recovery & Waiver of Subrogation. Landlord
          ----------------------------------------------------------
and Tenant each hereby waive any right of recovery against each other and the
partners, managers, members, shareholders, officers, directors and authorized
representatives of each other for any loss or damage that is covered by any
policy of property insurance maintained by either party (or required by this
Lease to be maintained) with respect to the Premises or the Property or any
operation therein, regardless of cause, including negligence (active or passive)
of the party benefiting from the waiver. If any such policy of insurance
relating to this Lease or to the Premises or the Property does not permit the
foregoing waiver or if the coverage under any such policy would be invalidated
as a result of such waiver, the party maintaining such policy shall obtain from
the insurer under such policy a waiver of all right of recovery by way of
subrogation against either party in connection with any claim, loss or damage
covered by such policy.

12.  DAMAGE OR DESTRUCTION.

     12.1 Landlord's Duty to Repair.
          -------------------------

          (a)  If all or a substantial part of the Premises are rendered
untenantable or inaccessible by damage to all or any part of the Property from
fire or other casualty then, unless either party is entitled to and elects to
terminate this Lease pursuant to Sections 12.2 - Landlord's Right to Terminate
and 12.3 - Tenant's Right to Terminate, Landlord shall, at its expense, use
reasonable efforts to repair and restore the Premises and/or the Property, as
the case may be, to substantially their former condition to the extent permitted
by then applicable Laws; provided, however, that in no event shall Landlord have
any obligation for repair or restoration beyond the extent of insurance proceeds
received by Landlord for such repair or restoration, or for any of Tenant's
personal property, Trade Fixtures or Alterations.

          (b)  If Landlord is required or elects to repair damage to the
Premises and/or the Property, this Lease shall continue in effect, but Tenant's
Base Rent and Additional Rent shall be abated with regard to any portion of the
Premises that Tenant is prevented from using by reason of such damage or its
repair from the date of the casualty until substantial completion of Landlord's
repair of the affected portion of the Premises as required under this Lease. In
no event shall Landlord be liable to Tenant by reason of any injury to or
interference with Tenant's business or property arising from fire or other
casualty or by reason of any repairs to any part of the Property necessitated by
such casualty.

                                      17
<PAGE>

     12.2 Landlord's Right to Terminate.  Landlord may elect to terminate this
          -----------------------------
Lease following damage by fire or other casualty under the following
circumstances :

          (a)  If, in the reasonable judgment of Landlord, the Premises and the
Property cannot be substantially repaired and restored under applicable Laws
within one (1) year from the date of the casualty;

          (b)  If, in the reasonable judgment of Landlord, adequate proceeds are
not, for any reason, made available to Landlord from Landlord's insurance
policies (and/or from Landlord's funds made available for such purpose, at
Landlord's sole option) to make the required repairs;

          (c)  If the Building is damaged or destroyed to the extent that, in
the reasonable judgment of Landlord, the cost to repair and restore the Building
would exceed twenty-five percent (25%) of the full replacement cost of the
Building, whether or not the Premises are at all damaged or destroyed; or

          (d)  If the fire or other casualty occurs during the last year of the
Term.

If any of the circumstances described in subsections (a), (b), (c) or (d) of
this Section 12.2 occur or arise, Landlord shall give Tenant notice within one
hundred and twenty (120) days after the date of the casualty, specifying whether
Landlord elects to terminate this Lease as provided above and, if not,
Landlord's estimate of the time required to complete Landlord's repair
obligations under this Lease.

     12.3 Tenant's Right to Terminate. If all or a substantial part of the
          ---------------------------
Premises are rendered untenantable or inaccessible by damage to all or any part
of the Property from fire or other casualty, and Landlord does not elect to
terminate as provided above, then Tenant may elect to terminate this Lease if
Landlord's estimate of the time required to complete Landlord's repair
obligations under this Lease is greater than nine (9) months, in which event
Tenant may elect to terminate this Lease by giving Landlord notice of such
election to terminate within thirty (30) days after Landlord's notice to Tenant
pursuant to Section 12.2 - Landlord's Right to Terminate.

     12.4 Waiver. Landlord and Tenant each hereby waive the provisions of any
          ------
applicable existing or future Law permitting the termination of a lease
agreement in the event of damage or destruction under any circumstances other
than as provided in Sections 12.2 - Landlord's Right to Terminate and 12.3 -
Tenant's Right to Terminate.

13.  CONDEMNATION.

     13.1 Definitions.
          -----------

          (a)  "Award" shall mean all compensation, sums, or anything of value
awarded, paid or received on a total or partial Condemnation.

          (b)  "Condemnation" shall mean (i) a permanent taking (or a temporary
taking for a period extending beyond the end of the Term) pursuant to the
exercise of the power of

                                      18
<PAGE>

condemnation or eminent domain by any public or quasi-public authority, private
corporation or individual having such power ("Condemnor"), whether by legal
proceedings or otherwise, or (ii) a voluntary sale or transfer by Landlord to
any such authority, either under threat of condemnation or while legal
proceedings for condemnation are pending.

          (c)  "Date of Condemnation" shall mean the earlier of the date that
title to the property taken is vested in the Condemnor or the date the Condemnor
has the right to possession of the property being condemned.

     13.2 Effect on Lease.
          ---------------

          (a)  If the Premises are totally taken by Condemnation, this Lease
shall terminate as of the Date of Condemnation. If a portion but not all of the
Premises is taken by Condemnation, this Lease shall remain in effect; provided,
however, that if the portion of the Premises remaining after the Condemnation
will be unsuitable for Tenant's continued use, then upon notice to Landlord
within thirty (30) days after Landlord notifies Tenant of the Condemnation,
Tenant may terminate this Lease effective as of the Date of Condemnation.

          (b)  If twenty-five percent (25%) or more of the Project or of the
parcel(s) of land on which the Building is situated or of the Parking Facility
or of the floor area in the Building is taken by Condemnation, or if as a result
of any Condemnation the Building is no longer reasonably suitable for use as an
office building, whether or not any portion of the Premises is taken, Landlord
may elect to terminate this Lease, effective as of the Date of Condemnation, by
notice to Tenant within thirty (30) days after the Date of Condemnation,
provided that Landlord terminates the leases for all other similarly situated
tenants in the Building.

          (c)  If all or a portion of the Premises is temporarily taken by a
Condemnor for a period not extending beyond the end of the Term, this Lease
shall remain in full force and effect.

     13.3 Restoration. If this Lease is not terminated as provided in Section
          -----------
13.2 - Effect on Lease, Landlord, at its expense, shall diligently proceed to
repair and restore the Premises to substantially its former condition (to the
extent permitted by then applicable Laws) and/or repair and restore the Building
to an architecturally complete office building; provided, however, that
Landlord's obligations to so repair and restore shall be limited to the amount
of any Award received by Landlord and not required to be paid to any Mortgagee
(as defined in Section 20.2 below). In no event shall Landlord have any
obligation to repair or replace any improvements in the Premises beyond the
amount of any Award received by Landlord for such repair or to repair or replace
any of Tenant's personal property, Trade Fixtures, or Alterations.

     13.4 Abatement and Reduction of Rent. If any portion of the Premises is
          -------------------------------
taken in a Condemnation or is rendered permanently untenantable by repairs
necessitated by the Condemnation, and this Lease is not terminated, the Base
Rent and Additional Rent payable under this Lease shall be proportionally
reduced as of the Date of Condemnation based upon the percentage of rentable
square feet in the Premises so taken or rendered permanently untenantable. In
addition, if this Lease remains in effect following a Condemnation and Landlord
proceeds to repair and restore the Premises, the Base Rent and Additional Rent
payable under this Lease shall

                                      19
<PAGE>

be abated during the period of such repair or restoration to the extent such
repairs prevent Tenant's use of the Premises.

     13.5 Awards. Any Award made shall be paid to Landlord, and Tenant
          ------
hereby assigns to Landlord, and waives all interest in or claim to, any such
Award, including any claim for the value of the unexpired Term; provided,
however, that Tenant shall be entitled to receive, or to prosecute a separate
claim for, an Award for a temporary taking of the Premises or a portion thereof
by a Condemnor where this Lease is not terminated (to the extent such Award
relates to the unexpired Term), or an Award or portion thereof separately
designated for relocation expenses or the interruption of or damage to Tenant's
business or as compensation for Tenant's personal property, Trade Fixtures or
Alterations.

     13.6 Waiver. Landlord and Tenant each hereby waive the provisions of any
          ------
applicable existing or future Law allowing either party to petition for a
termination of this Lease upon a partial taking of the Premises and/or the
Property.

14.  ASSIGNMENT AND SUBLETTING.

     14.1 Landlord's Consent Required. Tenant shall not assign this Lease or
          ---------------------------
any interest therein, or sublet or license or permit the use or occupancy of the
Premises or any part thereof by or for the benefit of anyone other than Tenant,
or in any other manner transfer all or any part of Tenant's interest under this
Lease (each and all a "Transfer"), without the prior written consent of Landlord
as set forth in this Article 14. If Tenant is a business entity, any direct or
indirect transfer of fifty percent (50%) or more of the ownership interest of
the entity (whether in a single transaction or in the aggregate through more
than one transaction) shall be deemed a Transfer. Notwithstanding any provision
in this Lease to the contrary, Tenant shall not mortgage, pledge, hypothecate or
otherwise encumber this Lease or all or any part of Tenant's interest under this
Lease.

     14.2 Landlord's Consent.
          ------------------

          (a)  Prior to any proposed Transfer, Tenant shall submit in writing to
Landlord (i) the name and legal composition of the proposed assignee, subtenant,
user or other transferee (each a "Proposed Transferee"); (ii) the nature of the
business proposed to be carried on in the Premises; (iii) a current balance
sheet, income statements for the last two years and such other financial and
other information concerning the Proposed Transferee as Landlord may require;
and (iv) a copy of a term sheet or letter of intent with the economic terms of
the proposed transaction, or the proposed assignment, sublease or other
agreement governing the proposed Transfer. Within fifteen (15) Business Days
after Landlord receives all such information it shall notify Tenant whether it
approves or disapproves such Transfer or if it elects to proceed under Section
14.7 - Landlord's Right to Space. If Landlord approves the terms of the proposed
Transfer submitted to Landlord and does not exercise its recapture right under
Section 14.7, within ninety (90) days after such approval Tenant shall submit to
Landlord a fully executed agreement on the terms set forth in Tenant's original
submission to Landlord. If Tenant's original submission was a letter of intent,
the final form of the proposed Transfer agreement shall be subject to Landlord's
reasonable approval. If Tenant does not submit such agreement to Landlord within
such ninety-

                                      20
<PAGE>

day (90) period, or if Tenant desires to modify the terms of the proposed
Transfer from those set forth in Tenant's original submission, Tenant shall
recommence the process under this Section 14.2(a) prior to entering into any
Transfer agreement.

          (b)  Landlord's consent to a proposed sublease or license shall,
subject to the other provisions of this Article 14, not be unreasonably
withheld. Tenant acknowledges and agrees that, among other circumstances for
which Landlord could reasonably withhold consent to a proposed Transfer, it
shall be reasonable for Landlord to withhold consent where (i) the Proposed
Transferee does not intend itself to occupy the entire portion of the Premises
assigned or sublet, (ii) Landlord reasonably disapproves of the Proposed
Transferee's business operating ability or history, reputation or
creditworthiness or the character of the business to be conducted by the
Proposed Transferee at the Premises, (iii) the Proposed Transferee is a
governmental agency or unit or an existing tenant in the Project, (iv) the
proposed Transfer would violate any "exclusive" rights of any tenants in the
Project, (v) Landlord or Landlord's agent has shown space in the Building to the
Proposed Transferee or responded to any inquiries from the Proposed Transferee
or the Proposed Transferee's agent concerning availability of space in the
Building, at any time within the preceding nine months, or (vi) Landlord
otherwise reasonably determines that the proposed Transfer would have the effect
of decreasing the value of the Building or increasing the expenses associated
with operating, maintaining and repairing the Property. Except for permitted
assignments under Section 14.2(c), Landlord may withhold its consent to a
proposed assignment of the Lease in its sole discretion. In no event may Tenant
publicly offer or advertise all or any portion of the Premises for assignment or
sublease at a rental less than that then sought by Landlord for a direct lease
(non-sublease) of comparable space in the Project.

          (c)  Notwithstanding anything to the contrary in this Article
14, the following transactions shall not require the consent of Landlord
provided that (i) Landlord shall receive prior notice thereof plus reasonable
evidence upon closing that the transaction is in fact one of the following, (ii)
the proposed Transfer complies with all other provisions of this Lease,
including, without limitation, this Article 14, does not alter Landlord's rights
under the Lease, and does not impose any additional obligation on Landlord; and
(iii) in the case of an assignment under this Section 14(c) the assignee shall
have a net worth at least equal to the greater of the net worth of the Tenant as
of the date hereof or as of the day immediately preceding such assignment:

          (1)  An assignment of the Lease to an entity succeeding to the
business and assets of Tenant, whether by way of merger, consolidation or
otherwise ("Successor");

          (2)  A sublease or assignment of the Lease to an entity that directly
or indirectly controls, is controlled by, or is under common control with Tenant
("Affiliate"). For purposes of this clause (2), control shall mean possession of
more than fifty percent (50%) of the shares or other beneficial ownership
interests of the entity in question together with the power to control and
manage the affairs thereof either directly or by election of directors and/or
officers.

     14.3 Excess Consideration. If Landlord consents to the Transfer and if the
          --------------------
consideration paid by any transferee (the "Transferee") for the Transfer,
including, in the case of a sublease, the

                                      21
<PAGE>

rent and other consideration payable by the subtenant exceeds (a) the amount of
Base Rent and Additional Rent payable hereunder applicable to the subleased
space in question, and (b) all costs reasonably incurred by Tenant in connection
with such sublease or assignment, then Tenant shall pay fifty percent (50%) of
such excess to Landlord as additional rent, within ten (10) days after receipt
by Tenant.

     14.4 No Release Of Tenant. No consent by Landlord to any Transfer, nor
          --------------------
any Transfer whether or not permitted under this Article 14, shall relieve
Tenant of any obligation to be performed by Tenant under this Lease, whether
occurring before or after such consent, assignment, subletting or other
Transfer. Each Transferee shall be jointly and severally liable with Tenant (and
Tenant shall be jointly and severally liable with each Transferee) for the
payment of rent (or, in the case of a sublease, rent in the amount set forth in
the sublease) and for the performance of all other terms and provisions of this
Lease and Landlord, at Landlord's option, may collect such rent directly from
such Transferee without releasing Tenant from Tenant's obligations. The consent
by Landlord to any Transfer shall not relieve Tenant or any such Transferee from
the obligation to obtain Landlord's express prior written consent to any
subsequent Transfer by Tenant or any Transferee. The acceptance of rent by
Landlord from any other person (whether or not such person is an occupant of the
Premises) shall not be deemed to be a waiver by Landlord of any provision of
this Lease or to be a consent to any Transfer.

     14.5 Expenses and Attorneys' Fees. Tenant shall pay to Landlord on demand
          ----------------------------
all reasonable costs and expenses (including reasonable attorneys' fees)
incurred by Landlord in connection with reviewing or consenting to any proposed
Transfer (including any request for consent to, or any waiver of Landlord's
rights in connection with, any security interest in any of Tenant's property at
the Premises).

     14.6 Effectiveness of Transfer. Prior to the date on which any permitted
          -------------------------
Transfer (whether or not requiring Landlord's consent) becomes effective, Tenant
shall deliver to Landlord a counterpart of the fully executed Transfer document
and Landlord's standard form of Consent to Assignment or Consent to Sublease
executed by Tenant and the Transferee in which each of Tenant and the Transferee
confirms its obligations pursuant to this Lease. Failure or refusal of a
Transferee to execute any such instrument shall not release or discharge the
Transferee from liability as provided herein. The voluntary, involuntary or
other surrender of this Lease by Tenant, or a mutual cancellation by Landlord
and Tenant, shall not work a merger, and any such surrender or cancellation
shall, at the option of Landlord, either terminate all or any existing subleases
or operate as an assignment to Landlord of any or all of such subleases.

     14.7 Landlord's Right to Space. Notwithstanding any of the above
          -------------------------
provisions of this Section to the contrary, if Tenant notifies Landlord that it
desires to enter into a Transfer, Landlord, in lieu of consenting to such
Transfer, may elect, within the time period set forth in Section 14(a) for such
election, (x) in the case of an assignment or a sublease of the entire Premises,
to terminate this Lease, or (y) in the case of a sublease of less than the
entire Premises, to terminate this Lease as it relates to the space proposed to
be subleased by Tenant. In such event, this Lease will terminate (or the space
proposed to be subleased will be removed from the Premises subject to this Lease
and the Base Rent and Tenant's Share under this Lease shall be proportionately
reduced) on the later

                                      22
<PAGE>

of: (i) 60 days after the date of Landlord's notice to Tenant making the
election set forth in this Section 14.7 or (ii) the date that the Transfer was
proposed to be effective, and Landlord may lease such space to any party,
including the prospective Transferee identified by Tenant.

     14.8 Assignment of Sublease Rents. Tenant hereby absolutely and irrevocably
          ----------------------------
assigns to Landlord any and all rights to receive rent and other consideration
from any sublease and agrees that Landlord, as assignee or as attorney-in-fact
for Tenant for purposes hereof, or a receiver for Tenant appointed on Landlord's
application may (but shall not be obligated to) collect such rents and other
consideration and apply the same toward Tenant's obligations to Landlord under
this Lease; provided, however, that Landlord grants to Tenant at all times prior
to occurrence of any breach or default by Tenant a revocable license to collect
such rents (which license shall automatically and without notice be and be
deemed to have been revoked and terminated immediately upon any Event of
Default).

15.  DEFAULT AND REMEDIES.

     15.1 Events of Default.  The occurrence of any of the following shall
          -----------------
constitute an "Event of Default" by Tenant:

          (a)  Tenant fails to make any payment of rent when due, or any amount
required to replenish the security deposit as provided in Section 4 above,
provided that, for the first two (2) times during any twelve (12) month period
that such a payment or amount is due and owing, Landlord shall provide written
notice to Tenant of such overdue amounts and an Event of Default shall only
occur if payment in full is not received by Landlord within five (5) days after
such written notice to Tenant. If such a payment or amount is due and owing more
than once during any twelve (12) month period, then, in such instance, Landlord
shall not be required to provide written notice to Tenant of such overdue
payment or amount and Tenant's failure to pay same shall constitute an immediate
Event of Default without further notice from Landlord.

          (b)  Tenant abandons the Premises.

          (c)  Tenant fails timely to deliver any subordination document,
estoppel certificate or financial statement requested by Landlord within the
applicable time period specified in Sections 20 - Encumbrances - and 21 -
Estoppel Certificates and Financial Statements - below.

          (d)  Tenant violates the restrictions on Transfer set forth in Section
14 - Assignment and Subletting.

          (e)  Tenant ceases doing business as a going concern; makes an
assignment for the benefit of creditors; is adjudicated an insolvent, files a
petition (or files an answer admitting the material allegations of a petition)
seeking relief under any state or federal bankruptcy or other statute, law or
regulation affecting creditors' rights; all or substantially all of Tenant's
assets are subject to judicial seizure or attachment and are not released within
30 days, or Tenant consents to or acquiesces in the appointment of a trustee,
receiver or liquidator for Tenant or for all or any substantial part of Tenant's
assets.

                                      23
<PAGE>

          (f) Tenant fails, within ninety (90) days after the commencement of
any proceedings against Tenant seeking relief under any state or federal
bankruptcy or other statute, law or regulation affecting creditors' rights, to
have such proceedings dismissed, or Tenant fails, within ninety (90) days after
an appointment, without Tenant's consent or acquiescence, of any trustee,
receiver or liquidator for Tenant or for all or any substantial part of Tenant's
assets, to have such appointment vacated.

          (g) Tenant fails to perform or comply with any provision of this Lease
other than those described in (a) through (f) above, and does not fully cure
such failure within thirty (30) days after notice to Tenant or, if such failure
cannot be cured within such thirty (30)-day period, Tenant fails within such
thirty (30)-day period to commence, and thereafter diligently proceed with, all
actions necessary to cure such failure as soon as reasonably possible but in all
events within ninety (90) days of such notice; provided, however, that if
Landlord in Landlord's reasonable judgment determines that such failure cannot
or will not be cured by Tenant within such ninety (90) days, then such failure
shall constitute an Event of Default immediately upon such notice to Tenant.

     15.2 Remedies. Upon the occurrence of an Event of Default, Landlord shall
          --------
have the following remedies, which shall not be exclusive but shall be
cumulative and shall be in addition to any other remedies now or hereafter
allowed by law:

          (a) Landlord may terminate this Lease at any time by written notice to
Tenant or by any other means available under law. Upon such termination,
Landlord shall be entitled, in accordance with the provisions of applicable law,
immediately to recover possession of the Premises from Tenant and those claiming
under Tenant. Tenant expressly acknowledges that in the absence of such written
notice from Landlord, no other act of Landlord, including re-entry into the
Premises, efforts to relet the Premises, reletting of the Premises for Tenant's
account, storage of Tenant's personal property and Trade Fixtures, acceptance of
keys to the Premises from Tenant or exercise of any other rights and remedies
under this Section, shall constitute an acceptance of Tenant's surrender of the
Premises or constitute a termination of this Lease or of Tenant's right to
possession of the Premises. Upon such termination in writing of this Lease, as
herein provided, this Lease shall terminate and Landlord shall be entitled to
recover damages from Tenant as provided herein and under any other applicable
existing or future Law providing for recovery of damages for such breach. In the
case of termination of this Lease pursuant to this Section, Tenant shall
reimburse Landlord for all expenses arising out of such termination, including
without limitation, all costs incurred in collecting amounts due from Tenant
under this Lease (including reasonable attorneys' fees, costs of litigation and
the like); all expenses incurred by Landlord in attempting to relet the Premises
or parts thereof (including advertisements, brokerage commissions, Tenant's
allowances, costs of preparing space, and the like); and all of Landlord's other
reasonable expenditures necessitated by the termination. The reimbursement from
Tenant shall be due and payable immediately from time to time upon notice from
Landlord that an expense has been incurred, without regard to whether the
expense was incurred before or after the termination.

          (b) Landlord may elect by written notice to Tenant within one year
following such termination to be indemnified for loss of rent by a lump sum
payment representing the then present value of the amount of rent and additional
charges that would have been paid in accordance

                                      24
<PAGE>

with this Lease for the remainder of the Term minus the then present value of
the aggregate fair market rent and additional charges payable for the Premises
for the remainder of the Term (if less than the rent and additional charges
payable hereunder), estimated as of the date of the termination, and taking into
account reasonable projections of vacancy and time required to re-lease the
Premises. (For the purposes of calculating the rent which would have been paid
hereunder for the lump sum payment calculation described herein, the last full
year's Additional Rent is to be deemed constant for each year thereafter. The
Federal Reserve discount rate (or equivalent) shall be used in calculating
present values.) Should the parties be unable to agree on a fair market rent,
the matter shall be submitted, upon the demand of either party, to the Boston,
Massachusetts office of the American Arbitration Association, with a request for
arbitration in accordance with the rules of the Association by a single
arbitrator who shall be a licensed real estate broker with at least ten years
experience as an appraiser of major office buildings in downtown Boston. The
parties agree that a decision of the arbitrator shall be conclusive and binding
upon them. If, at the end of the Term, the rent which Landlord has actually
received from the Premises is less than the aggregate fair market rent estimated
as aforesaid, Tenant shall thereupon pay Landlord the amount of such difference.
If Landlord does not make the election provided for in this Section, Tenant
shall indemnify Landlord for the loss of rent by a payment at the end of each
month which would have been included in the Term, representing the difference
between the rent which would have been paid in accordance with this Lease (Base
Rent and Additional Rent) and the rent actually derived from the Premises by
Landlord for such month (the amount of rent deemed derived shall be the actual
amount less any portion thereof attributable to Landlord's reletting expenses
that have not been reimbursed by Tenant thereunder).

     In lieu of any other damages or indemnity and in lieu of full recovery by
Landlord of all sums payable under all of the foregoing provisions of this
Section, Landlord may by written notice to Tenant within 6 months after
termination under any of the provisions contained in this Lease and before such
full recovery, elect to recover, and Tenant shall thereupon pay, as liquidated
damages, an amount equal to the lesser of (i) the aggregate of Base Rent and
Additional Rent for the balance of the Term had it not been terminated or (ii)
the aggregate thereof for the 12 months ending one year after the termination
date, plus in either case (iii) the amount of Base Rent and Additional Rent of
any kind accrued and unpaid at the time of termination and minus (iv) the amount
of any recovery by Landlord under the foregoing provisions of this Section
15.2(b) up to the time of payment of such liquidated damages (but reduced by any
amounts of reimbursement of reletting expenses). Liquidated damages hereunder
shall not be in lieu of any claims for reimbursement of reletting expenses.

          (c) Any obligation imposed by law upon Landlord to relet the Premises
shall be subject to the reasonable requirements of Landlord to lease to high
quality tenants and to develop the Building in a harmonious manner with an
appropriate mix of uses, tenants, floor areas and terms of tenancies, and the
like. Landlord's actual damages hereunder shall be subject to mitigation by the
amount of the damages that Tenant proves would have been avoided by Landlord in
the exercise of commercially reasonable efforts to relet the Premises; provided
that such reasonable efforts shall not require Landlord (i) to solicit or
negotiate with prospective new tenants until Landlord obtains full and complete
possession of the Premises, free of any claim by Tenant or its successors, (ii)
to relet the Premises prior to leasing any other space in the Project

                                      25
<PAGE>

then available or scheduled to become available, (iii) to relet the Premises in
a manner inconsistent with Landlord's leasing requirements under the preceding
sentence or inconsistent with the criteria for Landlord's approval of proposed
assignees or subtenants under Section 14, (iv) to expend any amounts on tenant
improvements or other leasing costs in excess of the levels in Landlord's budget
or leasing guidelines for the Project, or (v) to relet the Premises for a rental
less than the current fair market rental then prevailing for similar office
space in the Project. Tenant's liability hereunder shall not be diminished or
reduced if, or to the extent, that such reasonable efforts of Landlord to relet
the Premises are unsuccessful.

          (d) Any termination of this Lease and repossession of the Premises
under this Section shall be without prejudice to any remedies which Landlord
might otherwise have for arrears of rent or for a prior breach of the provisions
of this Lease. Tenant waives any statutory notice to quit and equitable rights
in the nature of further cure or redemption, and Tenant agrees that upon
Landlord's termination of this Lease Landlord shall be entitled to re-entry and
possession in accordance with the terms hereof. Tenant agrees that a notice by
Landlord alleging any default shall, at Landlord's option (the exercise of such
option shall be indicated by the inclusion of the words "notice to quit" in such
notice), constitute a statutory notice to quit. If Landlord exercises its option
to designate a notice of default hereunder as a statutory notice to quit, any
grace periods provided for herein shall run concurrently with any statutory
notice periods. Landlord and Tenant waive trial by jury in any action to which
they are parties. Tenant further agrees that it shall not interpose any
counterclaim or set-off in any summary proceeding or in any action based in
whole or in part on non-payment of rent unless Tenant has no right to commence
an independent proceeding to seek to recover on account of such claim.

          (e) Landlord may cure the Event of Default at Tenant's expense. If
Landlord pays any sum or incurs any expense in curing the Event of Default,
Tenant shall reimburse Landlord upon demand for the amount of such payment or
expense with interest at the Interest Rate from the date the sum is paid or the
expense is incurred until Landlord is reimbursed by Tenant.

          (f) After any termination of this Lease and repossession of the
Premises under this Section, Landlord may, without notice, store Tenant's
personal property (and those of any person claiming under Tenant) at the expense
and risk of Tenant or, if Landlord so elects, Landlord may sell such personal
property at public auction or auctions or at private sale or sales after seven
days notice to Tenant and apply the net proceeds to the earliest of installments
of rent or other charges owing Landlord.

16.  LATE CHARGE AND INTEREST.

     16.1 Late Charge. If any payment of rent is not received by Landlord when
          -----------
due on more than one occasion in any twelve-month period, Tenant shall pay to
Landlord on demand as a late charge an additional amount equal to four percent
(4%) of the overdue payment. A late charge shall not be imposed more than once
on any particular installment not paid when due, but imposition of a late charge
on any payment not made when due does not eliminate or supersede late charges
imposed on other (prior) payments not made when due or preclude imposition of a
late charge on other installments or payments not made when due.

                                      26
<PAGE>

     16.2 Interest. In addition to the late charges referred to above, which are
          --------
intended to defray Landlord's costs resulting from late payments, any payment
from Tenant to Landlord not paid when due shall at Landlord's option bear
interest from the date due until paid to Landlord by Tenant at the rate of
twelve percent (12%) per annum or the maximum lawful rate that Landlord may
charge to Tenant under applicable laws, whichever is less (the "Interest Rate").
Acceptance of any late charge and/or interest shall not constitute a waiver of
Tenant's default with respect to the overdue sum or prevent Landlord from
exercising any of its other rights and remedies under this Lease.

17.  WAIVER. No provisions of this Lease shall be deemed waived by Landlord
unless such waiver is in a writing signed by Landlord. The waiver by Landlord of
any breach of any provision of this Lease shall not be deemed a waiver of such
provision or of any subsequent breach of the same or any other provision of this
Lease. No delay or omission in the exercise of any right or remedy of Landlord
upon any default by Tenant shall impair such right or remedy or be construed as
a waiver. Landlord's acceptance of any payments of rent due under this Lease
shall not be deemed a waiver of any default by Tenant under this Lease
(including Tenant's recurrent failure to timely pay rent) other than Tenant's
nonpayment of the accepted sums, and no endorsement or statement on any check or
payment or in any letter or document accompanying any check or payment shall be
deemed an accord and satisfaction. Landlord's consent to or approval of any act
by Tenant requiring Landlord's consent or approval shall not be deemed to waive
or render unnecessary Landlord's consent to or approval of any subsequent act by
Tenant.

18.  ENTRY, INSPECTION AND CLOSURE. Upon reasonable oral or written notice to
Tenant (and without notice in emergencies), Landlord and its authorized
representatives may enter the Premises at all reasonable times to: (a) determine
whether the Premises are in good condition, (b) determine whether Tenant is
complying with its obligations under this Lease, (c) perform any maintenance or
repair of the Premises or the Building that Landlord has the right or obligation
to perform, (d) install or repair improvements for other tenants where access to
the Premises is required for such installation or repair, (e) serve, post or
keep posted any notices required or allowed under the provisions of this Lease,
(f) show the Premises to prospective brokers, agents, buyers, transferees,
Mortgagees or tenants, or (g) do any other act or thing necessary for the safety
or preservation of the Premises or the Building. When reasonably necessary
Landlord may temporarily close entrances, doors, corridors, elevators or other
facilities in the Building without liability to Tenant by reason of such
closure. Landlord shall conduct its activities under this Section in a manner
that will minimize inconvenience to Tenant (and Tenant's access to the Premises)
without incurring additional expense to Landlord. In no event shall Tenant be
entitled to an abatement of rent on account of any entry by Landlord, and
Landlord shall not be liable in any manner for any inconvenience, loss of
business or other damage to Tenant or other persons arising out of Landlord's
entry on the Premises in accordance with this Section. No action by Landlord
pursuant to this paragraph shall constitute an eviction of Tenant, constructive
or otherwise, entitle Tenant to an abatement of rent or to terminate this Lease
or otherwise release Tenant from any of Tenant's obligations under this Lease.

                                      27
<PAGE>

19.  SURRENDER AND HOLDING OVER.

     19.1 Surrender. Upon the expiration or termination of this Lease, Tenant
          ---------
shall surrender the Premises and all Tenant Improvements and Alterations to
Landlord broom-clean and in their original condition, except for reasonable wear
and tear, damage from casualty or condemnation and any changes resulting from
approved Alterations; provided, however, that prior to the expiration or
termination of this Lease (a) if Landlord removes the telephone and other
cabling installed in the Premises by the prior tenant, Tenant shall remove all
telephone and other cabling installed in the Building by Tenant, (b) Tenant
shall remove from the Premises all of Tenant's personal property and Trade
Fixtures and all Alterations that Landlord has elected to require Tenant to
remove as provided in Section 6.1 - Tenant Improvements & Alterations, and (c)
Tenant shall repair any damage caused by such removal of the items in clauses
(a) and (b). If such removal is not completed before the expiration or
termination of the Term, Landlord shall have the right (but no obligation) to
remove the same, and Tenant shall pay Landlord on demand for all costs of
removal and storage thereof and for the rental value of the Premises for the
period from the end of the Term through the end of the time reasonably required
for such removal. Landlord shall also have the right to retain or dispose of all
or any portion of such property if Tenant does not pay all such costs and
retrieve the property within ten (10) days after notice from Landlord (in which
event title to all such property described in Landlord's notice shall be
transferred to and vest in Landlord). Tenant waives all Claims against Landlord
for any damage or loss to Tenant resulting from Landlord's removal, storage,
retention, or disposition of any such property. Upon expiration or termination
of this Lease or of Tenant's possession, whichever is earliest, Tenant shall
surrender all keys to the Premises or any other part of the Building and shall
deliver to Landlord all keys for or make known to Landlord the combination of
locks on all safes, cabinets and vaults that may be located in the Premises.
Tenant's obligations under this Section shall survive the expiration or
termination of this Lease.

     19.2 Holding Over. If Tenant (directly or through any Transferee or other
          ------------
successor-in-interest of Tenant) remains in possession of the Premises after the
expiration or termination of this Lease, Tenant's continued possession shall be
on the basis of a tenancy at will or tenant by the month. No act or omission by
Landlord, other than its specific written consent, shall constitute permission
for Tenant to continue in possession of the Premises, and if such consent is
given or declared to have been given by a court judgment, Landlord may terminate
such holdover tenancy at any time upon thirty (30) days written notice. In the
event of any such holdover, Tenant shall continue to comply with or perform all
the terms and obligations of Tenant under this Lease, except that the monthly
Base Rent during Tenant's holding over shall be, for the first 30 days of such
holdover, at 150% of the Base Rent payable in the last full month prior to the
termination thereof and, thereafter, at twice the Base Rent payable in the last
full month prior to the termination hereof. Acceptance by Landlord of rent after
such termination shall not constitute a renewal or extension of this Lease; and
nothing contained in this provision shall be deemed to waive Landlord's right of
re-entry or any other right hereunder or at law. Notwithstanding the foregoing,
if Landlord desires to regain possession of the Premises promptly after the
termination or expiration hereof and prior to acceptance of rent for any period
thereafter, Landlord may, at its option, forthwith re-enter and take possession
of the Premises or any part thereof without process or if required with any
process required under applicable Laws. Tenant shall indemnify, defend and hold
Landlord harmless from

                                      28
<PAGE>

and against all Claims arising or resulting from Tenant's failure to timely
surrender the Premises, including (i) any loss, cost, or damages incurred by any
prospective tenant of the Premises, and (ii) Landlord's damages as a result of
such prospective tenant rescinding or refusing to enter into the prospective
lease of the Premises by reason of such failure to timely surrender the
Premises.

20.  ENCUMBRANCES.

     20.1 Subordination. This Lease is expressly made subject and subordinate to
          -------------
any mortgage, deed of trust, ground lease, underlying lease or like encumbrance
affecting any part of the Property or any interest of Landlord therein
("Encumbrance") which is now existing or hereafter executed or recorded;
provided, however, that such subordination shall only be effective, as to future
Encumbrances, if the holder of the Encumbrance agrees that this Lease shall
survive the termination of the Encumbrance by lapse of time, foreclosure or
otherwise so long as Tenant is not in default under this Lease. Provided the
conditions of the preceding sentence are satisfied, Tenant shall execute and
deliver to Landlord, within ten (10) days after written request therefor by
Landlord and in a form reasonably requested by Landlord, any additional
documents evidencing the subordination of this Lease with respect to any such
Encumbrance and the nondisturbance agreement of the holder of any such
Encumbrance. If the interest of Landlord in the Property is transferred pursuant
to or in lieu of proceedings for enforcement of any Encumbrance, Tenant shall
immediately and automatically attorn to the new owner, and this Lease shall
continue in full force and effect as a direct lease between the transferee and
Tenant on the terms and conditions set forth in this Lease. Landlord shall use
reasonable efforts to obtain a Subordination, Non-Disturbance and Attornment
Agreement from Landlord's current mortgagee with respect to this Lease in such
mortgagee's customary form. The costs, if any, incurred in securing such
agreement shall be at Tenant's expense.

     20.2 Mortgagee Protection. Tenant agrees to give any holder of any
          --------------------
Encumbrance covering any part of the Property ("Mortgagee"), by registered mail,
a copy of any notice of default served upon Landlord, provided that prior to
such notice Tenant has been notified in writing (by way of notice of assignment
of rents and leases, or otherwise) of the address of such Mortgagee. If Landlord
shall have failed to cure such default within thirty (30) days from the
effective date of such notice of default, then the Mortgagee shall have an
additional thirty (30) days within which to cure such default or if such default
cannot be cured within that time, then such additional time as may be necessary
to cure such default (including the time necessary to foreclose or otherwise
terminate its Encumbrance, if necessary to effect such cure), and this Lease
shall not be terminated so long as such remedies are being diligently pursued.

21.  ESTOPPEL CERTIFICATES AND FINANCIAL STATEMENTS.

     21.1 Estoppel Certificates. Within ten (10) business days after written
          ---------------------
request therefor, Tenant shall execute and deliver to Landlord, in a form
provided by or satisfactory to Landlord, a certificate stating that this Lease
is in full force and effect, describing any amendments or modifications hereto,
acknowledging that this Lease is subordinate or prior, as the case may be, to
any Encumbrance and stating any other information Landlord may reasonably
request, including the Term, the monthly Base Rent, the date to which Rent has
been paid, the amount of any security

                                      29
<PAGE>

deposit or prepaid rent, whether either party hereto is in default under the
terms of the Lease, and whether Landlord has completed its construction
obligations hereunder (if any). Any person or entity purchasing, acquiring an
interest in or extending financing with respect to the Property shall be
entitled to rely upon any such certificate. If Tenant fails to deliver such
certificate within ten (10) business days after Landlord's second written
request therefor, Tenant shall be liable to Landlord for any damages incurred by
Landlord including any profits or other benefits from any financing of the
Property or any interest therein which are lost or made unavailable as a result,
directly or indirectly, of Tenant's failure or refusal to timely execute or
deliver such estoppel certificate.

     21.2 Financial Statements. Within ten (10) days after written request
          --------------------
therefor, but not more than once a year, Tenant shall deliver to Landlord a copy
of the financial statements (including at least a year end balance sheet and a
statement of profit and loss) of Tenant (and of each guarantor of Tenant's
obligations under this Lease) for each of the two most recently completed years,
prepared in accordance with generally accepted accounting principles (and, if
such is Tenant's normal practice, audited by an independent certified public
accountant), all then available subsequent interim statements, and such other
financial information as may reasonably be requested by Landlord or required by
any Mortgagee.

22.  NOTICES. Any notice, demand, request, consent or approval that either party
desires or is required to give to the other party under this Lease shall be in
writing and shall be served personally, delivered by messenger or courier
service, or sent by U.S. certified mail, return receipt requested, postage
prepaid, addressed to the other party at the party's address for notices set
forth in the Basic Lease Information. Any notice required pursuant to any Laws
may be incorporated into, given concurrently with or given separately from any
notice required under this Lease. Notices shall be deemed to have been given and
be effective on the earlier of (a) receipt (or refusal of delivery or receipt);
or (b) one (1) day after acceptance by the independent service for delivery, if
sent by independent messenger or courier service, or three (3) days after
mailing if sent by mail in accordance with this Section. Either party may change
its address for notices hereunder, effective fifteen (15) days after notice to
the other party complying with this Section. If Tenant sublets the Premises,
notices from Landlord shall be effective on the subtenant when given to Tenant
pursuant to this Section.

23.  ATTORNEYS' FEES. In the event of any dispute between Landlord and Tenant in
any way related to this Lease, and whether involving contract and/or tort
claims, each party shall pay its own attorneys fees and costs except that the
non-prevailing party shall pay to the prevailing party all reasonable attorneys'
fees and costs and expenses of any type, without restriction by statute, court
rule or otherwise, incurred by the prevailing party in connection with any
action or proceeding (including any appeal and the enforcement of any judgment
or award), whether or not the dispute is litigated or prosecuted to final
judgment (collectively, "Fees"). The "prevailing party" shall be determined
based upon an assessment of which party's major arguments or positions taken in
the action or proceeding could fairly be said to have prevailed (whether by
compromise, settlement, abandonment by the other party of its claim or defense,
final decision, after any appeals, or otherwise) over the other party's major
arguments or positions on major disputed issues. Any Fees incurred in enforcing
a judgment shall be recoverable separately from

                                      30
<PAGE>

any other amount included in the judgment and shall survive and not be merged in
the judgment. The Fees shall be deemed an "actual pecuniary loss" within the
meaning of Bankruptcy Code Section 365(b)(1)(B), and notwithstanding the
foregoing, all Fees incurred by either party in any bankruptcy case filed by or
against the other party, from and after the order for relief until this Lease is
rejected or assumed in such bankruptcy case, will be "obligations of the debtor"
as that phrase is used in Bankruptcy Code Section 365(d)(3).

24.  QUIET POSSESSION. Subject to Tenant's full and timely performance of all of
Tenant's obligations under this Lease and subject to the terms of this Lease,
including Section 20 - Encumbrances, Tenant shall have the quiet possession of
the Premises throughout the Term as against any persons or entities lawfully
claiming by, through or under Landlord.

25. SECURITY MEASURES. Landlord may, but shall be under no obligation to,
implement security measures for the Property, such as the registration or search
of all persons entering or leaving the Building, requiring identification for
access to the Building, evacuation of the Building for cause, suspected cause,
or for drill purposes, the issuance of magnetic pass cards or keys for Building
or elevator access and other actions that Landlord deems necessary or
appropriate to prevent any threat of property loss or damage, bodily injury or
business interruption; provided, however, that such measures shall be
implemented in a way as not to inconvenience tenants of the Building
unreasonably. If Landlord uses an access card system, Landlord may require
Tenant to pay Landlord a deposit for each after-hours Building access card
issued to Tenant, in the amount specified in the Basic Lease Information. Tenant
shall be responsible for any loss, theft or breakage of any such cards, which
must be returned by Tenant to Landlord upon expiration or earlier termination of
the Lease. Landlord may retain the deposit for any card not so returned. If a
deposit is not required by Landlord, Landlord shall have the right to charge
Tenant for any card that is lost, stolen or broken or not returned upon
expiration or earlier termination of the Lease. Landlord shall at all times have
the right to change, alter or reduce any such security services or measures.
Tenant shall cooperate and comply with, and cause Tenant's Representatives and
Visitors to cooperate and comply with, such security measures. Landlord, its
agents and employees shall have no liability to Tenant or its Representatives or
Visitors for the implementation or exercise of, or the failure to implement or
exercise, any such security measures or for any resulting disturbance of
Tenant's use or enjoyment of the Premises.

26.  FORCE MAJEURE. If Landlord is delayed, interrupted or prevented from
performing any of its obligations under this Lease, including its obligations
under the Construction Rider (if any), and such delay, interruption or
prevention is due to fire, act of God, governmental act or failure to act, labor
dispute, unavailability of materials or any cause outside the reasonable control
of Landlord, then the time for performance of the affected obligations of
Landlord shall be extended for a period equivalent to the period of such delay,
interruption or prevention.

27.  RULES AND REGULATIONS. Tenant shall be bound by and shall comply with the
rules and regulations attached to and made a part of this Lease as Exhibit C to
                                                                   ---------
the extent those rules and regulations are not in conflict with the terms of
this Lease, as well as any reasonable nondiscriminatory rules and regulations
hereafter adopted by Landlord for all tenants of the Building, upon notice to
Tenant thereof (collectively, the "Building Rules"). Landlord shall not be

                                      31
<PAGE>

responsible to Tenant or to any other person for any violation of, or failure to
observe, the Building Rules by any other tenant or other person.

28.  LANDLORD'S LIABILITY. The term "Landlord," as used in this Lease, shall
mean only the owner or owners of the Building at the time in question. In the
event of any conveyance of title to the Building, then from and after the date
of such conveyance, the transferor Landlord shall be relieved of all liability
with respect to Landlord's obligations to be performed under this Lease after
the date of such conveyance. Notwithstanding any other term or provision of this
Lease, the liability of Landlord for its obligations under this Lease is limited
solely to Landlord's interest in the Building as the same may from time to time
be encumbered, and no personal liability shall at any time be asserted or
enforceable against any other assets of Landlord or against Landlord's partners
or members or its or their respective partners, shareholders, members,
directors, officers or managers on account of any of Landlord's obligations or
actions under this Lease.

29.  CONSENTS AND APPROVALS.

     29.1 Determination in Good Faith. Wherever the consent, approval, judgment
          ---------------------------
or determination of Landlord is required or permitted under this Lease, Landlord
may exercise its business judgment in granting or withholding such consent or
approval or in making such judgment or determination without reference to any
extrinsic standard of reasonableness, unless the specific provision contained in
this Lease providing for such consent, approval, judgment or determination
specifies that Landlord's consent or approval is not to be unreasonably
withheld, or that such judgment or determination is to be reasonable, or
otherwise specifies the standards under which Landlord may withhold its consent.
If it is determined that Landlord failed to give its consent where it was
required to do so under this Lease, Tenant shall be entitled to injunctive
relief but shall not to be entitled to monetary damages or to terminate this
Lease for such failure.

     29.2 No Liability Imposed on Landlord. The review and/or approval by
          --------------------------------
Landlord of any item or matter to be reviewed or approved by Landlord under the
terms of this Lease or any Exhibits or Addenda hereto shall not impose upon
Landlord any liability for the accuracy or sufficiency of any such item or
matter or the quality or suitability of such item for its intended use. Any such
review or approval is for the sole purpose of protecting Landlord's interest in
the Property, and no third parties, including Tenant or the Representatives and
Visitors of Tenant or any person or entity claiming by, through or under Tenant,
shall have any rights as a consequence thereof.

30.  WAIVER OF RIGHT TO JURY TRIAL. Landlord and Tenant waive their respective
rights to trial by jury of any contract or tort claim, counterclaim,
cross-complaint, or cause of action in any action, proceeding, or hearing
brought by either party against the other on any matter arising out of or in any
way connected with this Lease, the relationship of Landlord and Tenant, or
Tenant's use or occupancy of the Premises, including any claim of injury or
damage or the enforcement of any remedy under any current or future law,
statute, regulation, code, or ordinance.

31.  BROKERS. Landlord shall pay the fee or commission of the broker or brokers
identified in the Basic Lease Information (the "Broker") in accordance with
Landlord's separate written agreement with the Broker, if any. Tenant warrants
and represents to Landlord that in the

                                      32
<PAGE>

negotiating or making of this Lease neither Tenant nor anyone acting on Tenant's
behalf has dealt with any broker or finder who might be entitled to a fee or
commission for this Lease other than the Broker. Tenant shall indemnify and hold
Landlord harmless from any claim or claims, including costs, expenses and
attorney's fees incurred by Landlord asserted by any other broker or finder for
a fee or commission based upon any dealings with or statements made by Tenant or
Tenant's Representatives. Landlord agrees to indemnify and hold Tenant harmless
from and against any claim by third parties claiming by, through, or under
Landlord for commissions due or alleged to be due in connection with this Lease.

32. RELOCATION OF PREMISES. For the purpose of maintaining an economical and
proper distribution of tenants acceptable to Landlord throughout the Project,
Landlord shall have the right on one occasion during the Term to relocate the
Premises to a floor on or above the tenth (10th) floor within the Project,
provided that (a) the rentable and usable area of the new Premises is of
equivalent size to the existing Premises, subject to a variation of up to ten
percent (10%), provided that the Fixed Rent and Additional Rent payable
hereunder shall not be increased as a result of such relocation, (b) Landlord
shall pay the cost of providing tenant improvements in the new Premises, which
shall be substantially comparable in layout to those in the existing Premises,
and (c) Landlord shall pay reasonable costs (to the extent such costs are
submitted in writing to Landlord and approved in writing by Landlord prior to
such move) of moving Tenant's Trade Fixtures and personal property to the new
Premises and replacing stationery and business cards rendered incorrect as a
result of the relocation, and the costs of moving telephones and office
equipment and other personal property occasioned by the move. The new Premises
will be complete and ready for immediate occupancy by Tenant for the purpose of
doing business before the actual relocation takes place. Landlord shall deliver
to Tenant written notice of Landlord's election to relocate the Premises,
specifying the new location and the amount of rent payable therefor, at least
ninety (90) days prior to the date the relocation is to be effective.

33. ENTIRE AGREEMENT. This Lease, including the Exhibits and any Addenda
attached hereto, and the documents referred to herein, if any, constitute the
entire agreement between Landlord and Tenant with respect to the leasing of
space by Tenant in the Building, and supersede all prior or contemporaneous
agreements, understandings, proposals and other representations by or between
Landlord and Tenant, whether written or oral, all of which are merged herein.
Neither Landlord nor Landlord's agents have made any representations or
warranties with respect to the Premises, the Building, the Project or this Lease
except as expressly set forth herein, and no rights, easements or licenses shall
be acquired by Tenant by implication or otherwise unless expressly set forth
herein. The submission of this Lease for examination does not constitute an
option for the Premises and this Lease shall become effective as a binding
agreement only upon execution and delivery thereof by Landlord to Tenant.

34. MISCELLANEOUS. This Lease may not be amended or modified except by a writing
signed by Landlord and Tenant. Subject to Section 14 - Assignment and Subletting
and Section 28 - Landlord's Liability, this Lease shall be binding on and shall
inure to the benefit of the parties and their respective successors, assigns and
legal representatives. The determination that any provisions hereof may be void,
invalid, illegal or unenforceable shall not impair any other provisions hereof
and all such other provisions of this Lease shall remain in full force and
effect.

                                      33
<PAGE>

The unenforceability, invalidity or illegality of any provision of this Lease
under particular circumstances shall not render unenforceable, invalid or
illegal other provisions of this Lease, or the same provisions under other
circumstances. This Lease shall be construed and interpreted in accordance with
the laws (excluding conflict of laws principles) of the State in which the
Building is located. The provisions of this Lease shall be construed in
accordance with the fair meaning of the language used and shall not be strictly
construed against either party, even if such party drafted the provision in
question. When required by the context of this Lease, the singular includes the
plural. Wherever the term "including" is used in this Lease, it shall be
interpreted as meaning "including, but not limited to" the matter or matters
thereafter enumerated. The captions contained in this Lease are for purposes of
convenience only and are not to be used to interpret or construe this Lease. If
more than one person or entity is identified as Tenant hereunder, the
obligations of each and all of them under this Lease shall be joint and several.
Time is of the essence with respect to this Lease, except as to the conditions
relating to the delivery of possession of the Premises to Tenant. Neither
Landlord nor Tenant shall record this Lease; provided that, at the request of
either party, Landlord and Tenant shall, if appropriate, execute, acknowledge,
and deliver a notice of lease and a notice of termination of lease term, each in
recordable form. Such notices shall contain only the information required by law
for recording. Tenant hereby irrevocably appoints Landlord as Tenant's
attorney-in-fact (which appointment shall survive termination of the Term) with
full power of substitution to execute, acknowledge and deliver a notice of
termination of lease in Tenant's name if Tenant fails to do so within ten (10)
days after request therefor.

35.  AUTHORITY. If Tenant is a corporation, partnership, limited liability
company or other form of business entity, each of the persons executing this
Lease on behalf of Tenant warrants and represents that Tenant is a duly
organized and validly existing entity, that Tenant has full right and authority
to enter into this Lease and that the persons signing on behalf of Tenant are
authorized to do so and have the power to bind Tenant to this Lease. Tenant
shall provide Landlord upon request with evidence reasonably satisfactory to
Landlord confirming the foregoing representations. Landlord warrants and
represents that Landlord is a duly organized and validly existing entity, that
Landlord has full right and authority to enter into this Lease and that the
persons signing on behalf of Landlord are authorized to do so and have the power
to bind Landlord to this Lease. Landlord shall provide Tenant upon request with
evidence of such authority.

                                      34
<PAGE>

36.  VACANCY DURING LAST SIX MONTHS.

     If Tenant vacates substantially all of the Premises (or substantially all
of any major portion of the Premises, including a floor thereof) at any time
within the last six (6) months of the Term, Landlord may enter the Premises (or
such portion) and commence work necessary to prepare the space for future
tenants. The exercise of such right by Landlord will not affect Tenant's
obligations to pay Base Rent, Additional Rent, or any other additional charges
with respect to the Premises (or such portion), which obligations shall continue
without abatement until the end of the Term.

     IN WITNESS WHEREOF, Landlord and Tenant have entered into this Lease as a
sealed Massachusetts instrument as of the date first above written.

TENANT:                                       LANDLORD:

C-BRIDGE INTERNET SOLUTIONS, INC.             125 Summer Street Cornerstone LLC


By:  /s/                                      By:  /s/
    ----------------------------------------      ------------------------------
Name:  Rick Wester                            Name: A. Robert Paratte
      --------------------------------------       -----------------------------
Title:  CFO                                   Title:
       -------------------------------------         --------------------------


By:  /s/                                      By:
    ----------------------------------------      -----------------------------
Name:  Clifford B. Thompson                   Name:
      --------------------------------------        ----------------------------
Title:  VP & General Counsel                  Title:
       -------------------------------------        --------------------------

                                      35
<PAGE>

                                   EXHIBIT A
                                   ---------

                                 THE PREMISES
                                 ------------

Rough Drawing of floor plan omitted.

                               Exhibit A, Page 1
<PAGE>

                                   EXHIBIT B
                                   ---------

                              CONSTRUCTION RIDER
                              ------------------

     1.   Tenant Improvements. Landlord shall with reasonable diligence through
          -------------------
a contractor designated by Landlord (which contractor may be an affiliate of
Landlord) construct and install in the Premises the improvements and fixtures
provided for in this Construction Rider ("Tenant Improvements"). Upon request by
Landlord, Tenant shall designate in writing an individual authorized to act as
Tenant's Representative with respect to all approvals, directions and
authorizations pursuant to this Construction Rider.

          1.1  Plans. The Tenant Improvements shall be constructed substantially
               -----
as shown on the conceptual space plan for the Premises prepared by John Bryer
Architects who has been retained by Tenant as the space planner for the Premises
("Space Planner"), dated January 10, 2000 ("Space Plan").

     On or before April 1, 2000 Tenant will cause the Space Planner to
prepare and deliver to Landlord detailed plans and specifications sufficient to
permit the construction of the Tenant Improvements by Landlord's contractor
("Construction Documents"). Such Construction Documents shall be subject to
Landlord's approval, as provided in Article 6, and shall incorporate Building
standard finishes or such other finishes as Landlord may reasonably approve.
Landlord will bid the work to at least three (3) general contractors and provide
Tenant with a cost estimate for the work shown in the Construction Documents.
Tenant may include a general contractor and subcontractors (other than for
structural or building system trades) on the bid list. Tenant shall respond to
the Construction Documents and cost estimate within five (5) days after receipt
thereof, specifying any changes or modifications Tenant desires in the
Construction Documents. The Space Planner will then revise the Construction
Documents and resubmit them to Tenant and Landlord for their approval and
Landlord will provide Tenant with a revised cost estimate. Tenant shall approve
or disapprove the same within three (3) days after receipt. The revised
Construction Documents and cost estimate, as approved by Tenant and Landlord,
are hereinafter referred to as the "Final Construction Documents" and "Final
Cost Estimate," respectively.

     Additional interior decorating services and advice on the furnishing and
decoration of the Premises, such as the selection of fixtures, furnishings or
design of mill work, shall be provided by Tenant at its expense, but shall be
subject to the reasonable approval of Landlord.

     As part of the Tenant Improvements, Tenant shall have the right at its
sole cost and expense to install, operate, and maintain a separate security
system for access to the Premises ("Tenant's Security System") in accordance
with plans and specifications reasonably approved by Landlord. Upon the
expiration or earlier termination of the Lease, unless otherwise directed by
Landlord Tenant shall remove Tenant's Security System and repair any damage to
the Premises or Building caused by the installation and subsequent removal of
Tenant's Security System.

                               Exhibit B, Page 1
<PAGE>

          1.2  Construction. Upon approval by Landlord and Tenant of the Final
               ------------
Construction Documents and the Final Cost Estimate, Landlord shall proceed with
reasonable diligence to cause the Tenant Improvements to be Substantially
Completed on or prior to the Scheduled Commencement Date. The Tenant
Improvements shall be deemed to be "Substantially Completed" when they have been
completed in accordance with the Final Construction Documents except for
finishing details, minor omissions, decorations and mechanical adjustments of
the type normally found on an architectural "punch list". (The definition of
Substantially Completed shall also define the terms "Substantial Completion" and
"Substantially Complete.")

     Following Substantial Completion of the Tenant Improvements and before
Tenant takes possession of the Premises (or as soon thereafter as may be
reasonably practicable and in any event within 30 days after Substantial
Completion), Landlord and Tenant shall inspect the Premises and jointly prepare
a "punch list" of agreed items of construction remaining to be completed.
Landlord shall complete the items set forth in the punch list as soon as
reasonably possible and shall use reasonable efforts to complete the same within
thirty (30) days after the list of punchlist items has been agreed upon. Tenant
shall cooperate with and accommodate Landlord and Landlord's contractor in
completing the items on the punch list.

          1.3  Cost of Tenant Improvements. Landlord shall contribute
               ---------------------------
$32.00 per rentable square foot in the Premises (i.e., $629,824.00) toward the
cost of the design (including preparation of space plans and Construction
Documents), construction and installation of the Tenant Improvements, including
costs of cabling and wiring the Premises. The balance, if any, of the cost of
the Tenant Improvements ("Additional Cost"), including, but not limited to,
usual markups for overhead, supervision and profit, shall be paid by Tenant.
Tenant shall pay Landlord 50% of the Additional Cost based upon the Final Cost
Estimate prior to the commencement of construction of the Tenant Improvements.
The balance of the actual Additional Cost shall be paid to Landlord upon
Substantial Completion of the Tenant Improvements, within ten (10) days after
receipt of Landlord's invoice therefor. Landlord will use reasonable care in
preparing the cost estimates, but they are estimates only and do not limit
Tenant's obligation to pay for the actual Additional Cost of the Tenant
Improvements, whether or not it exceeds the estimated amounts. Tenant shall pay
Landlord a supervision fee equal to three percent (3%) of the total cost of the
Tenant Improvements in connection with Landlord's performance of the Tenant
Improvements. In connection with the Tenant Improvements, Landlord shall, at its
expense, remove the existing internal staircase between the 19/th/ and 20/th/
floors and fill in such stairway opening.

          1.4  Changes. If Tenant requests any change, addition or alteration in
               -------
or to any Final Construction Documents ("Changes") Landlord shall cause the
Space Planner to prepare additional Plans implementing such Change. Tenant shall
pay the cost of preparing additional Plans within ten (10) days after receipt of
Landlord's invoice therefor. As soon as practicable after the completion of such
additional Construction Documents, Landlord shall notify Tenant of the estimated
cost of the Changes. Within three (3) working days after receipt of such cost
estimate, Tenant shall notify Landlord in writing whether Tenant approves the
Change. If Tenant approves the Change, Landlord shall proceed with the Change
and Tenant shall be liable for any

                               Exhibit B, Page 2
<PAGE>

Additional Cost resulting from the Change. If Tenant fails to approve the Change
within such three (3) day period, construction of the Tenant Improvements shall
proceed as provided in accordance with the original Construction Documents.

          1.5  Delays. Tenant shall be responsible for, and shall pay to
               ------
Landlord, any and all costs and expenses incurred by Landlord in connection with
any delay in the commencement or completion of any Tenant Improvements and any
increase in the cost of Tenant Improvements caused by (i) Tenant's failure to
submit information to the Space Planner or approve any Space Plan, Construction
Documents or cost estimates within the time periods required herein, (ii) any
delays in obtaining any items or materials constituting part of the Tenant
Improvements requested by Tenant, (iii) any Changes, or (iv) any other delay
requested or caused by Tenant (collectively, "Tenant Delays").

     2.   Delivery of Premises. Upon Substantial Completion of the Tenant
          --------------------
Improvements, Landlord shall deliver possession of the Premises to Tenant. If
Landlord has not Substantially Completed the Tenant Improvements and tendered
possession of the Premises to Tenant on or before the Scheduled Commencement
Date specified in Section 2 - Term; Possession of the Lease, or if Landlord is
unable for any other reason to deliver possession of the Premises to Tenant on
or before such date, neither Landlord nor its representatives shall be liable to
Tenant for any damage resulting from the delay in completing such construction
obligations and/or delivering possession to Tenant and the Lease shall remain in
full force and effect unless and until it is terminated under the express
provisions of this Section. If any delays in Substantially Completing the Tenant
Improvements are attributable to Tenant Delays, then the Premises shall be
deemed to have been Substantially Completed and delivered to Tenant on the date
on which Landlord could have Substantially Completed the Premises and tendered
the Premises to Tenant but for such Tenant Delays.

     3.   Access to Premises. Landlord shall allow Tenant and Tenant's
          ------------------
Representatives to enter the Premises prior to the Commencement Date to permit
Tenant to make the Premises ready for its use and occupancy; provided, however,
that prior to such entry of the Premises, Tenant shall provide evidence
reasonably satisfactory to Landlord that Tenant's insurance, as described in
Section 11.1 - Tenant's Insurance of the Lease, shall be in effect as of the
time of such entry. Such permission may be revoked at any time upon twenty-four
(24) hours' notice, and Tenant and its Representatives shall not interfere with
Landlord or Landlord's contractor in completing the Building or the Tenant
Improvements.

         Tenant agrees that Landlord shall not be liable in any way for any
injury, loss or damage which may occur to any of Tenant's property placed upon
or installed in the Premises prior to the Commencement Date, the same being at
Tenant's sole risk, and Tenant shall be liable for all injury, loss or damage to
persons or property arising as a result of such entry into the Premises by
Tenant or its Representatives.

     4.   Ownership of Tenant Improvements. All Tenant Improvements, whether
          --------------------------------
installed by Landlord or Tenant, shall become a part of the Premises, shall be
the property of Landlord and, subject to the provisions of the Lease, shall be
surrendered by Tenant with the Premises,

                               Exhibit B, Page 3
<PAGE>

without any compensation to Tenant, at the expiration or termination of the
Lease in accordance with the provisions of the Lease.

                               Exhibit B, Page 4
<PAGE>

                                   EXHIBIT C
                                   ---------

                                BUILDING RULES
                                --------------

     The following Building Rules are additional provisions of the foregoing
Lease to which they are attached. The capitalized terms used herein have the
same meanings as these terms are given in the Lease.

     1.   Use of Common Areas. Tenant will not obstruct the sidewalks, halls,
          -------------------
passages, exits, entrances, elevators or stairways of the Building ("Common
Areas"), and Tenant will not use the Common Areas for any purpose other than
ingress and egress to and from the Premises. The Common Areas, except for the
sidewalks, are not open to the general public and Landlord reserves the right to
control and prevent access to the Common Areas of any person whose presence, in
Landlord's opinion, would be prejudicial to the safety, reputation and interests
of the Building and its tenants.

     2.   No Access to Roof. Tenant has no right of access to the roof of the
          -----------------
Building and will not install, repair or replace any antenna, aerial, aerial
wires, fan, air-conditioner or other device on the roof of the Building, without
the prior written consent of Landlord. Any such device installed without such
written consent is subject to removal at Tenant's expense without notice at any
time. In any event Tenant will be liable for any damages or repairs incurred or
required as a result of its installation, use, repair, maintenance or removal of
such devices on the roof and agrees to indemnify and hold harmless Landlord from
any liability, loss, damage, cost or expense, including reasonable attorneys'
fees, arising from any activities of Tenant or of Tenant's Representatives on
the roof of the Building.

     3.   Signage. No sign, placard, picture, name, advertisement or notice
          -------
visible from the exterior of the Premises will be inscribed, painted, affixed or
otherwise displayed by Tenant on or in any part of the Building without the
prior written consent of Landlord. Landlord reserves the right to adopt and
furnish Tenant with general guidelines relating to signs in or on the Building.
All approved signage will be inscribed, painted or affixed at Tenant's expense
by a person approved by Landlord, which approval will not be unreasonably
withheld.

     4.   Prohibited Uses. The Premises will not be used for manufacturing,
          ---------------
for the storage of merchandise held for sale to the general public, for lodging
or for the sale of goods to the general public. Tenant will not permit any food
preparation on the Premises except that Tenant may use Underwriters' Laboratory
approved equipment for brewing coffee, tea, hot chocolate and similar beverages
so long as such use is in accordance with all applicable federal, state and city
laws, codes, ordinances, rules and regulations.

     5.   Janitorial Services. Tenant will not employ any person for the
          -------------------
purpose of cleaning the Premises or permit any person to enter the Building for
such purpose other than Landlord's janitorial service, except with Landlord's
prior written consent. Tenant will not necessitate, and will be liable for the
cost of, any undue amount of janitorial labor by reason of Tenant's carelessness
in or indifference to the preservation of good order and cleanliness in the
Premises. Janitorial service will not be furnished to areas in the Premises on
nights when such

                               Exhibit C, Page 1
<PAGE>

areas are occupied after 7:00 p.m., unless such service is extended by written
agreement to a later hour in specifically designated areas of the Premises.

     6.   Keys and Locks. Landlord will furnish Tenant, free of charge, two
          --------------
keys to each door or lock in the Premises. Landlord may make a reasonable charge
for any additional or replacement keys. Tenant will not duplicate any keys,
alter any locks or install any new or additional lock or bolt on any door of its
Premises or on any other part of the Building without the prior written consent
of Landlord and, in any event, Tenant will provide Landlord with a key for any
such lock. On the termination of the Lease, Tenant will deliver to Landlord all
keys to any locks or doors in the Building which have been obtained by Tenant.

     7.   Freight. Upon not less than twenty-four hours prior notice to
          -------
Landlord, which notice may be oral, an elevator will be made available for
Tenant's use for transportation of freight, subject to such scheduling as
Landlord in its discretion deems appropriate. Tenant shall not transport freight
in loads exceeding the weight limitations of such elevator. Landlord reserves
the right to prescribe the weight, size and position of all equipment,
materials, furniture or other property brought into the Building, and no
property will be received in the Building or carried up or down the freight
elevator or stairs except during such hours and along such routes and by such
persons as may be designated by Landlord. Landlord reserves the right to require
that heavy objects will stand on wood strips of such length and thickness as is
necessary to properly distribute the weight. Landlord will not be responsible
for loss of or damage to any such property from any cause, and Tenant will be
liable for all damage or injuries caused by moving or maintaining such property.

     8.   Nuisances and Dangerous Substances. Tenant will not conduct itself
          ----------------------------------
or permit Tenant's Representatives or Visitors to conduct themselves, in the
Premises or anywhere on or in the Property in a manner which is offensive or
unduly annoying to any other Tenant or Landlord's property managers. Tenant will
not install or operate any phonograph, radio receiver, musical instrument, or
television or other similar device in any part of the Common Areas and shall not
operate any such device installed in the Premises in such manner as to disturb
or annoy other tenants of the Building. Tenant will not use or keep in the
Premises or the Property any kerosene, gasoline or other combustible fluid or
material other than limited quantities thereof reasonably necessary for the
maintenance of office equipment, or, without Landlord's prior written approval,
use any method of heating or air conditioning other than that supplied by
Landlord. Tenant will not use or keep any foul or noxious gas or substance in
the Premises or permit or suffer the Premises to be occupied or used in a manner
offensive or objectionable to Landlord or other occupants of the Building by
reason of noise, odors or vibrations, or interfere in any way with other tenants
or those having business therein. Tenant will not bring or keep any animals in
or about the Premises or the Property.

     9.   Building Name and Address. Without Landlord's prior written consent,
          -------------------------
Tenant will not use the name of the Building in connection with or in promoting
or advertising Tenant's business except as Tenant's address.

                               Exhibit C, Page 2
<PAGE>

     10.    Building Directory and Signage. A directory for the Building will
            ------------------------------
be provided for the display of the name and location of tenants. Landlord
reserves the right to approve any additional names Tenant desires to place in
the directory and, if so approved, Landlord may assess a reasonable charge for
adding such additional names. Tenant's name and suite number shall be displayed
on building standard signage in the elevator lobby of any multi-tenant floor on
which the Premises are located. If the Premises consist of an entire floor,
Tenant at its expense may affix a sign displaying its name in the elevator lobby
of such floor, subject to Landlord's prior approval.

     11.    Window Coverings. No curtains, draperies, blinds, shutters, shades,
            ----------------
awnings, screens or other coverings, window ventilators, hangings, decorations
or similar equipment shall be attached to, hung or placed in, or used in or with
any window of the Building without the prior written consent of Landlord, and
Landlord shall have the right to control all lighting within the Premises that
may be visible from the exterior of the Building.

     12.    Floor Coverings. Tenant will not lay or otherwise affix linoleum,
            ---------------
tile, carpet or any other floor covering to the floor of the Premises in any
manner except as approved in writing by Landlord. Tenant will be liable for the
cost of repair of any damage resulting from the violation of this rule or the
removal of any floor covering by Tenant or its contractors, employees or
invitees.

     13.    Wiring and Cabling Installations. Landlord will direct Tenant's
            --------------------------------
electricians and other vendors as to where and how data, telephone, and
electrical wires and cables are to be installed. No boring or cutting for wires
or cables will be allowed without the prior written consent of Landlord. The
location of burglar alarms, smoke detectors, telephones, call boxes and other
office equipment affixed to the Premises shall be subject to the written
approval of Landlord.

     14.    Office Closing Procedures. Tenant will see that the doors of the
            -------------------------
Premises are closed and locked and that all water faucets, water apparatus and
utilities are shut off before Tenant or its employees leave the Premises, so as
to prevent waste or damage. Tenant will be liable for all damage or injuries
sustained by other tenants or occupants of the Building or Landlord resulting
from Tenant's carelessness in this regard or violation of this rule. Tenant will
keep the doors to the Building corridors closed at all times except for ingress
and egress.

     15.    Plumbing Facilities. The toilet rooms, toilets, urinals, wash bowls
            -------------------
and other apparatus shall not be used for any purpose other than that for which
they were constructed and no foreign substance of any kind whatsoever shall be
disposed of therein. Tenant will be liable for any breakage, stoppage or damage
resulting from the violation of this rule by Tenant, its employees or invitees.

     16.    Use of Hand Trucks. Tenant will not use or permit to be used in the
            ------------------
Premises or in the Common Areas any hand trucks, carts or dollies except those
equipped with rubber tires and side guards or such other equipment as Landlord
may approve.

                               Exhibit C, Page 3
<PAGE>

     17.    Refuse. Tenant shall store all Tenant's trash and garbage within
            ------
the Premises or in other facilities designated By Landlord for such purpose.
Tenant shall not place in any trash box or receptacle any material which cannot
be disposed of in the ordinary and customary manner of removing and disposing of
trash and garbage in the city in which the Building is located without being in
violation of any law or ordinance governing such disposal. All trash and garbage
removal shall be made in accordance with directions issued from time to time by
Landlord, only through such Common Areas provided for such purposes and at such
times as Landlord may designate. Tenant shall comply with the requirements of
any recycling program adopted by Landlord for the Building.

     18.    Soliciting. Canvassing, peddling, soliciting and distribution of
            ----------
handbills or any other written materials in the Building are prohibited, and
Tenant will cooperate to prevent the same.

     19.    Parking. Tenant will use, and cause Tenant's Representatives and
            -------
Visitors to use, any parking spaces to which Tenant is entitled under the Lease
in a manner consistent with Landlord's directional signs and markings in the
Parking Facility. Specifically, but without limitation, Tenant will not park, or
permit Tenant's Representatives or Visitors to park, in a manner that impedes
access to and from the Building or the Parking Facility or that violates space
reservations for handicapped drivers registered as such with the Massachusetts
Registry of Motor Vehicles. Landlord may use such reasonable means as may be
necessary to enforce the directional signs and markings in the Parking Facility,
including but not limited to towing services, and Landlord will not be liable
for any damage to vehicles towed as a result of non-compliance with such parking
regulations.

     20.    Fire, Security and Safety Regulations. Tenant will comply with all
            -------------------------------------
safety, security, fire protection and evacuation measures and procedures
established by Landlord or any governmental agency.

     21.    Responsibility for Theft. Tenant assumes any and all responsibility
            ------------------------
for protecting the Premises from theft, robbery and pilferage, which includes
keeping doors locked and other means of entry to the Premises closed.

     22.    Sales and Auctions. Tenant will not conduct or permit to be
            ------------------
conducted any sale by auction in, upon or from the Premises or elsewhere in the
Property, whether said auction be voluntary, involuntary, pursuant to any
assignment for the payment of creditors or pursuant to any bankruptcy or other
insolvency proceeding.

     23.    Thermostats. Office Tenants shall not tamper with or attempt to
            -----------
adjust temperature control thermostats in their leased premises. Landlord shall
make adjustments in thermostats upon request by tenants.

     24.    Emergency Stairs. Building emergency stairs shall be used only for
            ----------------
emergency purposes, unless specifically approved by Landlord in its sole
discretion.

                               Exhibit C, Page 4
<PAGE>

     25.   Non-Smoking Policy. The common areas of the Project, including
           -----------------
without limitation the garage and the exterior areas adjacent to building
entrances, are non smoking areas. Tenants who permit smoking within their leased
premises shall, at their sole cost and expense, install filtering systems
sufficient to prevent smoke and odors from entering other tenants' premises, the
plenum space above the leased premises, or the building's HVAC system. Upon
request from Landlord, Tenant shall inform its employees of the building's
non-smoking policy in building common areas and shall take reasonable measures
to enforce the policy with respect to its employees.

     26.   Waiver of Rules. Landlord may waive any one or more of these
           ---------------
Building Rules for the benefit of any particular tenant or tenants, but no such
waiver by Landlord will be construed as a waiver of such Building Rules in favor
of any other tenant or tenants nor prevent Landlord from thereafter enforcing
these Building Rules against any or all of the tenants of the Building.

     27.   Effect on Lease. These Building Rules are in addition to, and shall
           ---------------
not be construed to in any way modify or amend, in whole or in part, the terms,
covenants, agreements and conditions of the Lease. Violation of these Building
Rules constitutes a failure to fully perform the provisions of the Lease, as
referred to in Section 15.1 - "Events of Default".

     28.   Non-Discriminatory Enforcement. Subject to the provisions of the
           ------------------------------
Lease (and the provisions of other leases with respect to other tenants),
Landlord shall use reasonable efforts to enforce these Building Rules in a
non-discriminatory manner, but in no event shall Landlord have any liability for
any failure or refusal to do so (and Tenant's sole and exclusive remedy for any
such failure or refusal shall be injunctive relief preventing Landlord from
enforcing any of the Building Rules against Tenant in a manner that
discriminates against Tenant).

     29.   Additional and Amended Rules. Landlord reserves the right to
           ----------------------------
rescind or amend these Building Rules and/or adopt any other and reasonable
rules and regulations as in its judgment may from time to time be needed for the
safety, care and cleanliness of the Building and for the preservation of good
order therein.
<PAGE>

                                   EXHIBIT D
                                   ---------

                               LANDLORD SERVICES
                               -----------------

1.   Water used by the building standard cooling, drinking and sanitation
     systems, and for maintenance and janitorial services.

2.   Central heat and air conditioning in season, at such temperatures and
     in such amounts as are from time to time furnished
     to tenants in comparable buildings in downtown Boston, or as may be
     permitted to controlled by applicable laws, ordinances, rules and
     regulations.

3.   Maintenance, repairs, structural and exterior maintenance (including
     exterior glass and glazing), painting and electric lighting service for all
     Common Areas, Building Common Areas and General Common Areas in the manner
     and to the extent customarily provided by landlords in first-class office
     buildings in Boston.

4.   Janitorial service after Business Hours on Business Days.

5.   Electricity for typewriters, voice writers, calculating machines, low
     consumption duplicating machines, low consumption electronic data
     processing equipment, and other machines of similar low electrical
     consumption (it being agreed that Tenant's total consumption for such items
     shall not exceed six (6) watts per square foot of Net Rentable Area per
     month at 120 volts).

6.   Initial lamps, bulbs, starters and ballasts for building standard fixtures
     used within the Leased Premises, and electricity for lighting such
     fixtures.

7.   Security for the Building.

8.   Public elevator service serving the floors on which the Leased Premises are
     situated, including a service elevator.

                               Exhibit D, Page 1
<PAGE>

9.   A general directory board or electronic device on which Tenant shall be
     entitled to have its name shown.

                               Exhibit D, Page 2
<PAGE>

                                   EXHIBIT E
                                   ---------

                          ADDITIONAL PROVISIONS RIDER
                          ---------------------------

1.   PARKING.
     -------

     (a) Tenant's Parking Rights. Landlord shall provide Tenant, on an
         -----------------------
unassigned and non-exclusive basis, for use by Tenant and Tenant's
Representatives and Visitors, at the users' sole risk, thirteen (13) parking
spaces in the Parking Facility. The parking spaces to be made available to
Tenant hereunder may contain a reasonable mix of spaces for compact cars and up
to ten percent (10%) of the unassigned spaces may also be designated by Landlord
as Building visitors' parking.

     (b) Availability of Parking Spaces. Landlord shall take reasonable actions
         ------------------------------
to ensure the availability of the parking spaces leased by Tenant, but Landlord
does not guarantee the availability of those spaces at all times against the
actions of other tenants of the Building and users of the Parking Facility.
Access to the Parking Facility may, at Landlord's option, be regulated by card,
pass, bumper sticker, decal or other appropriate identification issued by
Landlord. Landlord retains the right to revoke the parking privileges of any
user of the Parking Facility who violates the rules and regulations governing
use of the Parking Facility (and Tenant shall be responsible for causing any
employee of Tenant or other person using parking spaces allocated to Tenant to
comply with all parking rules and regulations).

     (c) Monthly Parking Rental. Tenant shall pay to Landlord, as monthly rent
         ----------------------
for the parking spaces leased by Tenant hereunder, a "Monthly Parking Rental"
per space, which shall be the "Prevailing Parking Rental" for such parking
spaces in effect from time to time. The Prevailing Parking Rental shall be
determined by Landlord, based on the monthly rental charged by Landlord from
time to time for spaces in the Parking Facility, and the unassigned or reserved
nature of such parking spaces. The Building's unreserved parking rate is
currently $325.00 per space per month. Tenant's Monthly Parking Rental shall be
paid on the first day of each month during the Term of this Lease; provided,
however, that in the event Tenant fails to pay Tenant's Monthly Parking Rental
when due, Landlord may assess a late charge of $50.00 on the delinquent amount,
which late charge shall be in addition to the late charge and interest that may
be charged pursuant to Section 16.1 - Late Charge and Interest in the Lease, and
provided further that in the event: (i) Tenant fails to pay Tenant's Monthly
Parking Rental within thirty (30) days of Landlord's notice of such delinquency,
or (ii) Tenant does not use any parking spaces for a period of more than sixty
(60) days, Landlord shall have the right by notice to Tenant permanently to
terminate Tenant's rights to use parking spaces hereunder, whether or not
Landlord declares a default under the Lease.

     (d) Assignment and Subletting. Notwithstanding any other provision of the
         -------------------------
Lease to the contrary, Tenant shall not assign its rights to the parking spaces
or any interest therein, or

                               Exhibit E, Page 1
<PAGE>

sublease or otherwise allow the use of all or any part of the parking spaces to
or by any other person, except with Landlord's prior written consent, which may
be granted or withheld by Landlord in its sole discretion, provided that the
parking spaces hereunder may be transferred as part of any assignment of this
Lease or a sublease that is permitted or approved under Article 14 of the Lease.
In the event of any separate assignment or sublease of parking space rights that
is approved by Landlord, Landlord shall be entitled to receive, as additional
Rent hereunder, one hundred percent (100%) of any profit received by Tenant in
connection with such assignment or sublease.

     (e)  Condemnation, Damage or Destruction. In the event the Parking Facility
          -----------------------------------
is the subject of a Condemnation, or is damaged or destroyed, and this Lease is
not terminated, and if in such event the available number of parking spaces in
the Parking Facility is permanently reduced, then Tenant's rights to use parking
spaces hereunder may, at the election of Landlord, thereafter be reduced in
proportion to the reduction of the total number of parking spaces in the Parking
Facility, and the Monthly Parking Rental payable hereunder shall be reduced
proportionately. In such event, Landlord reserves the right to reduce the number
of parking spaces to which Tenant is entitled or to relocate some or all of the
parking spaces to which Tenant is entitled to other areas in the Parking
Facility.

2.   EXTENSION OPTION.
     ----------------

     (a)  Provided that C-Bridge Internet Solutions, Inc. has not assigned this
Lease or sublet more than 25% of the Rentable Area of the Premises other than to
a Successor or Affiliate under Article 14 (it being intended that all rights
pursuant to this provision are and shall be personal to the original Tenant or
its Successor or Affiliate under Article 14 under this Lease and shall not be
transferable or exercisable for the benefit of any other Transferee), and
provided Tenant is not in default beyond applicable notice and grace periods
under this Lease at the time of exercise or at any time thereafter until the
beginning of any such extension of the Term, Tenant shall have the option (the
"Extension Option") to extend the Term for one (1) additional period of five (5)
years (the "Extension Period"), subject to and in accordance with the terms and
conditions of this Section. The exercise of any Extension Option by Tenant shall
be irrevocable and shall cover the entire Premises leased by Tenant pursuant to
this Lease. Any Extension Option shall terminate if not exercised precisely in
the manner provided herein. Any extension of the Term shall be upon all the
terms and conditions set forth in this Lease and all Exhibits thereto, except
that: (i) Tenant shall have no further option to extend the Term of the Lease,
other than as specifically set forth herein; (ii) Landlord shall not be
obligated to contribute funds toward the cost of any remodeling, renovation,
alteration or improvement work in the Premises.

     If Tenant wishes to consider exercising the Extension Option, Tenant shall
first give written notice to Landlord, at least twelve (12) months, but not more
than fifteen (15) months, prior to the expiration of the initial Term, of
Tenant's request for Landlord's determination of the Base Rent for the Extension
Period (the "Extension Rent"). The Extension Rent shall be the Fair Market Base
Rental for the Premises (as determined hereunder), but not less than the Base
Rent in effect immediately prior to the Extension Period. Failure timely to give
a notice as

                               Exhibit E, Page 2
<PAGE>

specified under this subsection (a) shall constitute an irrevocable waiver of
Tenant's right to extend the Term.

     (b)  If Tenant timely delivers a notice under subsection (a) above,
Landlord shall furnish Tenant with Landlord's proposed Extension Rent no later
than ten (10) months prior to the date the Term is then scheduled to expire.

     (c)  On or before the date that is one (1) month after Landlord furnishes
the amount of its proposed Extension Rent to Tenant under subsection (b) above,
Tenant shall either (i) waive the Extension Option, (ii) exercise the Extension
Option by giving Landlord notice to such effect accepting Landlord's proposed
Extension Rent, or (iii) exercise the Extension Option but cause the matter of
the Extension Rent to be submitted to arbitration in accordance with subsection
(f) below by giving Landlord notice to such effect, which notice shall state
Tenant's determination of the Fair Market Base Rental (as hereinafter defined).
Failure timely to give a notice exercising the Extension Option as specified
under this subsection (c) shall constitute an irrevocable waiver of Tenant's
right to extend the Term.

     (d)  If Tenant shall exercise the Extension Option in accordance with
this Section, the provisions of this Section shall be self-operative, but upon
request by either party after determination of the Extension Rent, the parties
shall execute an agreement specifying the Extension Rent and acknowledging the
extension of the Term.

     (e)  "Fair Market Base Rental" shall mean the fair market rent for the
Premises for the Extension Period under the terms of this Lease, as though the
Premises had been maintained in the condition the Premises are required to be
maintained under the Lease. In making such determination, when reference is made
to lease transactions for comparable space in the Building or other comparable
buildings in downtown Boston, Massachusetts, appropriate adjustments shall be
made to the rental rates for such transactions to take into account all relevant
factors. Fair Market Base Rental shall also reflect the then prevailing rental
structure for comparable office buildings in the general vicinity of the
Property, so that if, for example, at the time Fair Market Base Rental is being
determined the prevailing rental structure for comparable space and for
comparable lease terms includes periodic rental adjustments or escalations, Fair
Market Base Rental shall reflect such rental structure.

     (f)  If Tenant elects to proceed under subsection (c)(iii) (exercising the
Extension Option and submitting the matter of the Extension Rent to arbitration
by determination of the Fair Market Base Rental), Landlord and Tenant shall
mutually select a licensed real estate broker who is active in the leasing of
first-class high-rise office space in the general vicinity of the Property.
Landlord shall submit Landlord's determination of Fair Market Base Rental and
Tenant shall submit Tenant's determination of Fair Market Base Rental to such
broker, at such time or times and in such manner as Landlord and Tenant shall
agree (or as directed by the broker if Landlord and Tenant do not promptly
agree). The broker shall select either Landlord's or Tenant's final
determination of the Fair Market Base Rental, submitted at the commencement of
the broker determination process, as the Extension Rent, and such determination
of the Extension Rent shall be binding on Landlord and Tenant. If Tenant's
determination of the Fair

                               Exhibit E, Page 3
<PAGE>

Market Base Rental is selected as the Extension Rent, then Landlord shall bear
all of the broker's cost and fees. If Landlord's determination of the Fair
Market Base Rental is selected as the Extension Rent, then Tenant shall bear all
of the broker's cost and fees.

     (g)  In the event the Fair Market Base Rental for any Extension Period
has not been determined at such time as Tenant is obligated to pay Base Rent for
such Extension Period, Tenant shall pay as Base Rent pending such determination,
the Base Rent in effect for such space immediately prior to the Extension
Period; provided, that upon the determination of the applicable Fair Market Base
Rental, any shortage of Base Rent paid, together with interest at the rate
specified in the Lease, shall be paid to Landlord by Tenant.

     (h)  In no event shall the Base Rent during any Extension Period (adjusted
to reflect the Base Operating Costs and Base Taxes in effect immediately prior
to such Extension Period) be less than the Base Rent in effect immediately prior
to such Extension Period.

     (i)  The term of this Lease, whether consisting of the Initial Term alone
or the Initial Term as extended by any Extension Period (if any Extension Option
is exercised), is referred to in this Lease as the "Term."

3.   RIGHT OF FIRST OFFER.
     --------------------

     (a)  Provided that C-Bridge Internet Solutions, Inc. has not assigned this
Lease or sublet more than 25% of the Premises other than to a Successor or
Affiliate under Article 14 (it being intended that all rights pursuant to this
provision are and shall be personal to the original Tenant under this Lease or
its Successor or Affiliate under Article 14 and shall not be transferable or
exercisable for the benefit of any other Transferee), and provided Tenant is not
in default beyond applicable notice and grace periods under this Lease at the
time of the exercise of any such right or at any time thereafter until delivery
of possession of the space to Tenant, subject to any and all rights granted by
Landlord or asserted by others with respect to such space (including renewal and
extension rights and rights of first offer, first negotiation, first refusal or
other expansion rights and including the rights that Landlord may heretofore or
hereafter grant to Charles Schwab, Inc., Robinson Humphrey/Salomon Brothers,
LLC, or their affiliates), and subject to Landlord's right to extend or renew
any then existing lease of the space or otherwise to lease the space to any
tenant, subtenant or other occupant of the space, Tenant shall have a one-time
right of first offer to lease the following space in the Building: Any
contiguous space on the 18th floor.

     (b)  Such right of first offer (i) may only be exercised with respect to
space which has been previously leased and becomes vacant during the Term
following expiration or other termination of the previous lease, and (ii) may
only be exercised with respect to all of the space being offered by Landlord. If
any space qualifying for such right of first offer becomes available, Landlord
shall offer to lease such space to Tenant at the same rent and on the same terms
that Landlord intends to offer to other prospective tenants. Tenant shall have
ten (10) Business Days following receipt of Landlord's offer with respect to any
such space within which to notify Landlord in writing of its intention to lease
such space, and such notice, if given by Tenant, shall constitute an acceptance
of Landlord's terms for the lease of such space. If Tenant

                               Exhibit E, Page 4
<PAGE>

exercises such right of first offer, the space to be leased by Tenant shall be
leased on the same terms and conditions as are contained in this Lease except
for the economic and other terms specifically set forth in Landlord's notice,
and the parties shall execute an amendment to this Lease to include such space
in the Premises and otherwise to provide for the leasing of such space on such
terms. If Tenant fails so to exercise Tenant's right of first offer within such
ten (10) Business Day period, Landlord may thereafter lease such space to other
prospective tenants; provided, however, that if Landlord proposes to lease such
space at an effective rent that is less than ninety percent (90%) of the
effective rent proposed to Tenant, or upon other terms which are substantially
more favorable to the prospective tenant, Landlord shall first re-offer such
space to Tenant at such lower rent and/or more favorable terms in accordance
with the provisions of this paragraph.

     (c)  If Tenant does not lease the right of first offer space from Landlord
when it is first offered to Tenant by Landlord or when it is re-offered to
Tenant because the economic terms first offered to Tenant have materially
changed, as described in the last sentence of paragraph (b) above, then this
right of first offer shall terminate and Tenant shall have no further rights to
lease any of the right of first offer space.

4.   LETTER OF CREDIT

     (a)  Tenant shall deliver to Landlord a clean, unconditional, irrevocable,
transferable letter of credit (the "Letter of Credit") in form, and issued by a
financial institution ("Issuer") satisfactory to Landlord in Landlord's sole
discretion. The Letter of Credit shall be in the amount of Seven Hundred Seventy
Seven Thousand Four Hundred Thirty Nine and 00/100 Dollars ($777,439.00), name
Landlord as the beneficiary thereunder, and provide that draws thereunder will
be honored upon receipt by Issuer of a written statement signed by Landlord or
Landlord's authorized agent stating that Landlord is entitled to draw down on
the Letter of Credit pursuant to the terms of this Lease. Landlord shall be
entitled to draw the entire amount under the Letter of Credit if either (i)
Tenant does not deliver to Landlord a replacement letter of credit from Issuer
or another financial institution satisfactory to Landlord in the amount and form
of the initial Letter of Credit no later than one month before the expiration
date of the then existing Letter of Credit, or (ii) upon a proposed sale or
lease of the Building Tenant does not deliver to any new landlord a replacement
Letter of Credit pursuant to the provisions of (d) below. If Tenant is in
default under the Lease beyond any applicable notice and cure period, Landlord
shall be entitled to draw under the Letter of Credit only an amount equal to the
amount of any monetary default as defined below (or, only if partial draws are
not permitted, the entire amount of the Letter of Credit). As used herein,
"monetary default" means any delinquent installment of Base Rent, Additional
Rent or Rent under this Lease (as and when Tenant fails to pay the same beyond
any applicable notice and cure period contained in this Lease), plus any damages
to which Landlord is entitled under the Lease. Landlord agrees that the Letter
of Credit may also provide for partial draws by Landlord. To the extent not
applied by Landlord pursuant to the provisions of the Lease any amount drawn
under the Letter of Credit shall be held or applied by Landlord as a Security
Deposit, subject to the terms of Section 4 of this Lease.

                               Exhibit E, Page 5
<PAGE>

     (b) The Letter of Credit shall be issued and delivered to Landlord within
fifteen (15) days after complete execution of this Lease by Landlord and Tenant.
If Tenant Fails to deliver to Landlord the Letter of Credit when required, such
failure shall constitute an Event of Default under the Lease.

     (c) Tenant shall not assign or encumber or attempt to assign or encumber
the Letter of Credit and neither Landlord nor its successors or assign shall be
bound by any such assignment or encumbrance or attempted assignment or
encumbrance.

     (d) If Landlord shall be holding the Letter of Credit as security, then, in
the event of a proposed sale or lease of the Building by Landlord, Tenant will,
upon ten (10) Business Days' notice, at its sole cost and expense, cause the
issuing bank to consent to the assignment or to issue a substitute letter of
credit on identical terms except for the stated beneficiary, from the same
issuing bank or another bank acceptable to Landlord in Landlord's sole
discretion, naming the new landlord as the beneficiary thereof upon delivery by
Landlord of the then outstanding Letter of Credit.

     (e) For so long as no default has occurred under the Lease (and no event
has occurred or condition exists which with notice and/or passage of time would
give rise to such default), on each anniversary of the Commencement Date, the
amount of the Letter of Credit shall be reduced by 20% of the initial Letter of
Credit amount. Such reduction of the Letter of Credit shall not affect the
amount of the cash Security Deposit held by Landlord under Section 4.

                               Exhibit E, Page 6
<PAGE>

                                   EXHIBIT F

                        APPROVED LETTER OF CREDIT FORM

[Letterhead of Issuing Bank]
[must be a Bank whose location, credit and practices Landlord has approved]


RE:   IRREVOCABLE COMMERCIAL LETTER OF CREDIT NO. _________

TO:   [Name of project owner] ("Landlord"), ____________________________________
__________________ [Landlord's address]

Gentlemen:

We hereby issue our Irrevocable Commercial Letter of Credit in your favor, for
the account of _____________________________ [name of tenant and type of entity
(e.g. "ABC Corporation, a California corporation")] ("Tenant"), in the amount of
______________________________ Dollars ($__________). This amount is available
to you on presentation of your sight draft drawn upon us referring to the above
letter of credit number, date and amount being drawn hereunder, accompanied by
the signed statement of you or your authorized agent, Cornerstone Properties
Limited Partnership dba Wilson Cornerstone Properties Limited Partnership, that
the amount drawn hereunder is being drawn pursuant to the terms of the
_______________ [title of lease document (e.g. Office Lease, Lease Agreement,
etc.)] dated as of __________, between Tenant, as tenant, and Landlord, as
landlord, for certain premises located at __________________________ (the
"Lease").

Any draft presented for payment must be presented on or before ________________
[term should be at least one year], the date this Letter of Credit expires.
Partial drawings are permitted.

If you sell or otherwise transfer any interest in the "Building" (as defined in
the Lease), in the land upon which the same is located, in the Lease, or in
Landlord (including consolidations, mergers or other entity changes), you shall
have the right to transfer this Letter of Credit to your transferee(s),
successors or assigns.

We hereby certify that this is an unconditional and irrevocable Letter of Credit
and agree that a draft drawn under and in compliance with the terms hereof will
be honored upon presentation at our office at [Boston or New York].

This Letter of Credit shall automatically be extended and renewed for successive
one year periods at the end of the stated expiration date and each anniversary
thereof unless we notify you in writing, no later than forty-five (45) days
prior to the then applicable expiration date, that we will not extend and renew
the Letter of Credit for another one year term.

                               Exhibit F, Page 1
<PAGE>

Except to the extent inconsistent with the express provisions hereof, this
Letter of Credit is subject to and governed by Uniform Customs and Practice for
Documentary Credits (1993 Revision) International Chamber of Commerce
publication number 500.

                                              [Name of Bank]



                                      ---------------------------------
                                             Authorized Signature

                               Exhibit F, Page 2