Document:

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                                 OFFICE LEASE

                               150 Apollo Drive

                           Chelmsford, Massachusetts

                                   Landlord:

                         Farley White Associates, LLC

                                    Tenant:

                            Sycamore Networks, Inc.
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                               TABLE OF CONTENTS
                               -----------------

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ARTICLE I DEMISING CLAUSE AND DEFINED TERMS................................   1
  1.1  Demising Clause.....................................................   1
  1.2  Defined Terms.......................................................   1

ARTICLE II PREMISES AND TERM...............................................   3
  2.1  The Premises, Common Areas and Parking..............................   3
  2.2  Term................................................................   5

ARTICLE III RENT...........................................................   6
  3.1  Base Rent...........................................................   6
  3.2  Adjustment for Operating Expenses...................................   7
  3.3  Tenant's Electricity................................................  11

ARTICLE IV CONSTRUCTION....................................................  11
  4.1  Building Construction...............................................  11
  4.2  Leasehold Improvements by Tenant....................................  12
  4.3  Alterations by Tenant...............................................  13

ARTICLE V LANDLORD'S OBLIGATIONS AND RIGHTS................................  14
  5.1  Services Furnished by Landlord......................................  14
  5.2  Repairs and Maintenance.............................................  15
  5.3  Quiet Enjoyment.....................................................  15
  5.4  Insurance...........................................................  15
  5.5  Access to Premises..................................................  15
  5.6  Right to Cease Providing Services...................................  16
  5.7  Failure to Provide Services and Repairs.............................  16

ARTICLE VI TENANT'S COVENANTS..............................................  16
  6.1  Repair and Yield Up.................................................  16
  6.2  Use.................................................................  17
  6.3  Assignment; Sublease................................................  18
  6.4  Indemnity; Assumption of Risk.......................................  21
  6.5  Tenant's Insurance..................................................  21
  6.6  Right of Entry......................................................  22
  6.7  Payment of Taxes....................................................  22
  6.8  Environmental Compliance............................................  23
  6.9  Utilities...........................................................  24
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                           Table of Contents (cont.)
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ARTICLE VII DEFAULT........................................................  24
  7.1  Events of Default...................................................  24
  7.2  Damages.............................................................  25

ARTICLE VIII CASUALTY AND EMINENT DOMAIN...................................  26
  8.1  Termination or Restoration; Rent Adjustment.........................  26
  8.2  Eminent Domain Damages..............................................  28
  8.3  Temporary Taking....................................................  28

ARTICLE IX RIGHTS OF PARTIES HOLDING PRIOR INTERESTS.......................  28
  9.1  Lease Subordinate - Superior........................................  28
  9.2  Rights of Mortgagee to Cure.........................................  30

ARTICLE X MISCELLANEOUS....................................................  30
  10.1  Representations by Tenant..........................................  30
  10.2  Notices............................................................  30
  10.3  No Waiver or Oral Modification.....................................  30
  10.4  Partial Invalidity.................................................  31
  10.5  Certain Landlord Remedies..........................................  31
  10.6  Tenant's Estoppel Certificate......................................  31
  10.7  Waiver of Subrogation..............................................  32
  10.8  All Agreements; No Representations.................................  32
  10.9  Brokerage..........................................................  32
  10.10  Successors and Assigns............................................  32
  10.11  Construction of Document..........................................  32
  10.12  Disputes Provisions...............................................  33
  10.13  Surrender.........................................................  33
  10.14  Holdover..........................................................  33
  10.15  Late Payment......................................................  33
  10.16  Force Majeure.....................................................  33
  10.17  Limitation On Liability...........................................  34
  10.18  Submission Not An Option..........................................  34
  10.19  Security Deposit..................................................  35
  10.20  Evidence of Authority.............................................  36
  10.21  Notice of Lease...................................................  36
  10.22  Rules and Regulations.............................................  36

ARTICLE XI DETERMINATION OF FAIR MARKET RENT AND TENANT OPTIONS............  37
  11.1  Fair Market Rent...................................................  37
  11.2  Option to Extend...................................................  38
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EXHIBITS
--------

There are attached hereto and incorporated as a part of this Lease:

EXHIBIT A -- Legal Description of the Lot
EXHIBIT B -- Base Building Specifications

                                      -i-
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                                   ARTICLE I
                       DEMISING CLAUSE AND DEFINED TERMS

     1.1  Demising Clause.
          ---------------

This lease (the "Lease") is made and entered into by and between the Landlord
and the Tenant, as defined below, as of the Date of Lease.  In consideration of
the mutual covenants made herein, Landlord hereby leases to Tenant, and Tenant
hereby leases from Landlord, the Premises as defined below, on all of the terms
and conditions set forth herein.

     1.2  Defined Terms.
          -------------

The terms listed below shall have the following meanings throughout this Lease:

          (a)  "LANDLORD":               Farley White Associates LLC, a
                                         Massachusetts limited liability
                                         company

          (b)  "LANDLORD'S ADDRESS":     c/o Roger W. Altreuter
                                         CB Richard Ellis-N.E.
                                         Partners 600 Atlantic
                                         Avenue Boston, MA 02210

          (c)  "TENANT":                 Sycamore Networks, Inc.

          (d)  "TENANT'S ADDRESS":       10 Elizabeth Drive
                                         Chelmsford, MA 01824-4111
                                         Attention: Mr. Peter Hamel

          (e)  "LOT"                     The land described on Exhibit A
                                         attached to this Lease.

          (f)  "BUILDING":               The principal building to be
                                         constructed on the Lot in
                                         accordance with the Base Building
                                         Specifications (as hereinafter
                                         defined) and Article IV of this
                                         Lease, which building is to be
                                         known as 150 Apollo Drive,
                                         Chelmsford, Massachusetts.

          (g)  "PROPERTY":               The Lot, the Building and the other
                                         improvements to be constructed on
                                         the Lot in accordance with the Base
                                         Building Specifications and Article
                                         IV of this Lease.

                                      -1-
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          (h)  "PREMISES":               All interior areas of the Building
                                         other than Common Areas (as defined in
                                         Section 2.1(b) below) and any
                                         Recaptured Space (as defined in
                                         Section 6.3(a) below).

          (i)  "RENTABLE SQUARE FEET IN
               THE PREMISES":            79,873 rentable square feet.

          (j)  "TENANT'S PERCENTAGE"     100% (subject to Section 6.3(d) below)

          (k)  "SCHEDULED
               COMMENCEMENT DATE":       August 1, 2000.

          (l)  "TERM":                   The period beginning on the
                                         Commencement Date (as defined in
                                         Section 2.2(a) of this Lease) and
                                         ending on the last day of the one-
                                         hundred-twentieth full calendar month
                                         after the Commencement Date, subject to
                                         extension pursuant to Section 11.2.

          (m)  "BASE RENT":              From the Commencement Date through the
                                         end of the sixtieth full calendar month
                                         of the Term: $998,412.50 per year, in
                                         equal monthly installments of
                                         $83,201.04 per month.

                                         From the sixty-first through the one-
                                         hundred-twentieth full calendar month
                                         of the Term:   $1,078,285.50 per year
                                         in equal monthly installments of
                                         $89,857.13 per month.

          (n)  "PERMITTED USES":         Administration, sales and other general
                                         office purposes, research and
                                         development (including engineering
                                         laboratories), and design, assembly,
                                         testing, storage and shipping of
                                         electronic products and components,
                                         consistent with

                                      -2-
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                                         Section 6.2 hereof, provided that no
                                         more than twenty percent (20%) of the
                                         Rentable Square Feet in the Premises
                                         may be used for assembly, testing,
                                         storage and shipping of electronic
                                         products and components.

          (o)  "BROKER(S)":              CB Richard Ellis/Whittier Partners and
                                         Boston Real Estate Partners

          (p)  "SECURITY DEPOSIT":       $500,000.00 (see Section 10.19)

          (q)  "DATE OF LEASE":          ______________________________________
                                         (The date on which both parties have
                                         executed this Lease)

                                  ARTICLE II
                               PREMISES AND TERM

     2.1  The Premises, Common Areas and Parking.
          --------------------------------------

          (a)  Landlord hereby leases to Tenant, and Tenant hereby leases from
Landlord, the Premises.  The Premises extend from the top surface of all
subfloors to the bottom surfaces of all ceilings, but do not include the Common
Areas, the exterior faces of exterior walls and exterior window glass, and the
pipes, ducts, conduits, wires and other fixtures, systems and equipment serving
any Recaptured Space or the Common Areas exclusively or in common with the
Premises.  In the event that Landlord recaptures a portion of the Premises
pursuant to section 6.3(d) or Tenant for any other reason is not leasing the
entire rentable area of the Building, the Premises shall not include the
interior face of demising walls.  All Building's Systems and Recaptured
Utilities (as hereinafter defined) shall be located either in the Common Areas
or above dropped ceilings.

          (b)  Tenant shall have the right to use the Common Areas of the
Building and Property in common with other tenants, if any.  Notwithstanding the
foregoing, Tenant's use of the access drives and Utility Servicing Equipment
(defined below) servicing the Property shall be in common with others entitled
to use the same (including, without limitation, the occupants of the neighboring
building located at 100 Apollo Drive).  The "Common Areas" shall include (i) if
Landlord terminates this Lease with respect to any portion of the Premises under
Section 6.3(d) of this Lease, the entrances, lobbies, corridors, stairways and
elevators necessary for access to the Premises and/or the Recaptured Space, (ii)
the Building's electrical room and sprinkler room, (iii) all parking areas,
loading areas and loading docks on the Property, (iv) all driveways and walkways
on the Property or on other property but necessary for access to the Building or
said parking areas, (v) if Landlord terminates this Lease with respect to any
portion of the Premises under Section 6.3(d) of this Lease, the common toilets,
corridors and elevator lobbies of any multi-tenant floor, (vi) loading areas or
loading docks,  (vii) if Landlord

                                      -3-
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terminates this Lease with respect to any portion of the Premises under Section
6.3(d) of this Lease, all pipes, wires, ducts, conduits and other systems and
equipment located in any area of the Building outside of the Premises but
necessary to provide heating, ventilation, air-conditioning, electricity,
plumbing, telecommunications and other utilities and services to the Premises,
and (ix) whether located on the Property or on other property (but only to the
extent Landlord owns or has easements or other rights to use such property), all
wires, cables, poles, mains, conduits, trenches, manholes and other fixtures,
facilities and equipment necessary or convenient to provide electricity,
telephone, cable, gas, water, sewer and other utility and telecommunications
services to the Building ("Utility Servicing Equipment"). All use of the Common
Areas shall be subject to the Rules and Regulations, if any, adopted by Landlord
in accordance with Section 10.22 below. Landlord may at any time, upon
reasonable advance written notice to Tenant (except in an emergency) make any
changes, additions, improvements, repairs or replacements to the exterior areas
of the Property and the portions of the Building other than the Premises,
including the Common Areas, that it considers desirable, which changes,
additions, improvements, repairs or replacements shall be of a quality equal to
or better than the Common Areas on the Property as of the Date of Lease, and, in
so doing, Landlord may use or temporarily close any of the Common Areas or
permanently change their configuration; provided, however, (a) Tenant shall have
access to the Building at all times, (b) Landlord shall not cause or permit a
permanent reduction in the number of parking spaces on the Property as of the
Date of Lease, and (c) Landlord shall not otherwise materially interfere with
Tenant's use and enjoyment of the Building and the Common Areas, except in the
case of emergencies and maintenance, repairs and replacements required of
Landlord under this Lease, with respect to which Landlord shall use reasonable
efforts to minimize interference with Tenant's normal activities, but no such
interference shall constitute constructive eviction or give rise to any
abatement of rent or liability of Landlord to Tenant unless such interference
materially reduces the Tenant's use and enjoyment of the Premises or the Common
Areas, or is caused by Landlord's negligence, willful misconduct, or breach of
Landlord's covenants hereunder.

          (c)  The parking areas for the Building shall include at least 314
parking spaces. The Tenant shall be entitled to use the Tenant's Percentage of
the Building's parking spaces.  Tenant acknowledges that its parking use of the
parking areas shall be on an unreserved basis (and, to the extent Tenant is not
leasing the entire Building,   in common with tenants of any Recaptured Space),
and that parking spaces shall be used solely for Tenant's employees and
visitors.  Landlord shall not grant to others rights to use parking spaces
numbering in excess of 314 (or such greater number of legal spaces as may be
available on the Property from time to time), less Tenant's Percentage of 314.
Tenant shall reasonably cooperate with Landlord to assure that Tenant and its
employees and visitors observe all Rules and Regulations established by Landlord
from time to time in accordance with Section 10.22 below, and to assure that
Tenant and its employees and visitors do not use more parking spaces than the
number of parking spaces provided to Tenant hereunder.  Subject to Article VIII
of this Lease, Landlord shall not be liable to Tenant, and this Lease shall not
be affected, if any parking rights of Tenant hereunder are impaired by any law,
ordinance or other governmental regulation imposed after the Date of Lease.

                                      -4-
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     2.2  Term.
          ----

          (a)  Both parties shall be bound by all the terms of this Lease as of
the Date of Lease.  The Term shall begin on the Commencement Date and shall
continue for the length of the Term set forth in Section 1.2 unless sooner
terminated as hereinafter provided.  The "Commencement Date" shall be the date
when (i) the entire Building and the Common Areas are Ready for Occupancy (as
hereinafter defined) and (ii) Landlord has delivered the Premises to Tenant free
of all tenants and occupants.  The Building and the Common Areas shall be "Ready
for Occupancy" when Landlord delivers to Tenant a certificate from Landlord's
architect certifying that the Landlord's Work (as hereafter defined) is complete
except for Punch List Items.  "Punch List Items" shall include only those
components of Landlord's Work which, while incomplete and while being completed,
do not materially interfere with the performance or completion of the Leasehold
Improvements or, after completion of the Leasehold Improvements, with Tenant's
use and enjoyment of the Premises.  Landlord shall complete all Punch List Items
within 30 days after the Commencement Date, except for (a) Punch List Items
which cannot be completed while all or any portion of the Leasehold Improvements
remain incomplete, which Punch List Items Landlord shall complete as soon as
reasonably practicable but in no event more than 30 days after the completion of
such Leasehold Improvements, and (b) Punch List Items which cannot be completed
due to seasonal conditions, which Landlord shall complete as soon as seasonal
conditions permit.

          (b)  Landlord shall permit Tenant and its agents, employees and
contractors to have reasonable access to the Premises before the Commencement
Date for the purpose of inspecting the conduct and completion of the Landlord's
Work and taking measurements and taking other actions associated with the
preparation of plans and specifications for the Leasehold Improvements.  Upon
Tenant's request, Landlord shall permit Tenant and its agents, employees and
contractors to begin and perform the construction and installation of the
Leasehold Improvements on the Premises before the Commencement Date, provided
that such construction and installations shall not interfere with the
performance, or delay the completion, of the Landlord's Work and Tenant complies
with any restrictions on such construction and installations reasonably imposed
by Landlord to avoid and prevent any such interference or delays.  Tenant, and
Tenant's contractors, agents and employees, shall coordinate such access,
construction and installations with Landlord and its agents, employees and
contractors.  Any such access, construction and installations shall be subject
to all of the terms and conditions of this Lease, including without limitation
all such terms relating to insurance, except that Tenant shall have no
obligation to pay Base Rent, Operating Expenses, Taxes or other additional rent
until the Commencement Date.

          (c)  Landlord shall use reasonable efforts to have the Building and
the Common Areas Ready for Occupancy on the Scheduled Commencement Date.  If the
entire Premises are not Ready for Occupancy on the Scheduled Commencement Date,
Landlord shall not be subject to any liability for such failure, and such
failure shall not affect the validity of this Lease, but Tenant shall not be
liable for any Base Rent, Operating Expenses, Taxes or other additional rent
until the Commencement Date.  However, if the entire Premises are not Ready for
Occupancy because the presence or actions of Tenant or its agents, employees or
contractors on the Premises before the Commencement Date has delayed Landlord in
completing the Landlord's Work, then the Commencement Date shall be the date
that the entire Premises would

                                      -5-
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have been Ready for Occupancy except for any such delay caused by Tenant or its
agents, employees or contractors. If the Commencement Date has not occurred on
or before February 1, 2001, Tenant shall thereafter have the right, as its sole
and exclusive remedy at law or in equity for the failure of the Commencement
Date to have occurred, to terminate this Lease by written notice to Landlord,
provided that such termination right shall expire and be null and void if not
exercised prior to the earlier of (i) the Commencement Date or (ii) June 1,
2001. In the event Tenant timely exercises such termination right, this Lease
shall terminate thirty (30) days after notice of such exercise is given, unless
the Commencement Date occurs within such thirty (30) day period, in which event
such termination shall be null and void.

          (d)  Notwithstanding the foregoing, Tenant shall have the right to
terminate this Lease as of the last day of the sixtieth full calendar month of
the Term (the "Termination Date") by providing written notice to Landlord at
least twelve (12) months prior to the Termination Date.  In the event Tenant
exercises such termination right, Tenant shall pay to Landlord, on the date such
notice is given, as a termination payment, the sum of One Million Two Hundred
Thousand Dollars ($1,200,000.00).  In the event Tenant fails to timely pay such
sum to Landlord, Tenant's exercise of the aforesaid termination right shall be
null and void, and the Term of this Lease shall continue as if no such notice
had been given.

                                  ARTICLE III
                                     RENT

     3.1  Base Rent.
          ---------

          (a)  Tenant shall pay the Base Rent each month in advance on the first
day of each calendar month during the Term.  For any partial calendar month at
the beginning or end of the Term, Tenant shall pay a proportional share of the
amount that would be due for a full calendar month, which proportion shall be
equal to the fraction of the total days of such calendar month included in the
Term, and, with respect to a partial month at the beginning of the Term, Tenant
shall pay such proportional share on the Commencement Date.  In addition to the
Base Rent, Tenant shall pay all additional rent and rental adjustments provided
herein at the times set forth herein, or if no time for payment is specified,
then payment shall be made within 30 days after Tenant's receipt of an invoice
from Landlord or another billing authority. All payments shall be made to
Landlord at Landlord's Address or such other place as Landlord may designate in
writing, without prior demand and without abatement, deduction or offset except
as may be specifically set forth herein.  Tenant shall not pay, and Landlord
shall not accept, any rental payment more than one month in advance. Landlord
acknowledges receipt from Tenant of the sum of One Hundred Fifty Thousand
Dollars ($150,000.00), which sum shall be applied against Tenant's first
payments on account of Base Rent and additional rent obligations under this
Lease. All charges to be paid by Tenant hereunder, other than Base Rent, shall
be considered additional rent for the purpose of this Lease, and the words
"rent" or "Rent" as used in this Lease shall mean both Base Rent and such
additional rent unless the context specifically or clearly indicates that only
the Base Rent is referenced.

                                      -6-
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     3.2  Adjustment for Operating Expenses.
          ---------------------------------

          (a)  Throughout the Term, Tenant shall pay, as additional rent,
Tenant's Share of Expenses for the Property.  For each Fiscal Year (as
hereinafter defined) during the Term, "Tenant's Share of Expenses" shall consist
of Tenant's Percentage of the total Operating Expenses (as hereinafter defined)
for the Property and the total Taxes (as hereinafter defined) for the Property
for that Fiscal Year; provided, however, if the Term includes only a portion of
any Fiscal Year, either due to the beginning, termination or expiration of the
Term or a change in the period of the Fiscal Year, the Expenses for such Fiscal
Year shall be prorated based on the fraction of the total days in such Fiscal
Year that are included in the Term, and Tenant shall pay only such prorated
Expenses.  In the event that Landlord terminates this Lease with respect to any
portion of the Premises under Section 6.3(a) or Tenant does not otherwise lease
100% of the rentable area within the Building, "Tenant's Share of Expenses"
shall also include a commercially reasonable charge for the provision of
services to operate the Building during periods other than 8:00 a.m. to 6:00
p.m. on weekdays and 9:00 a.m. to 1:00 p.m. on Saturdays and to operate the
Building on holidays (which are all days on which commercial banks in Boston,
Massachusetts are authorized or required by law to close) (such periods being
referred to herein as "Non-Business Hours") that are fairly allocable to the
Premises, if such services are requested by Tenant or are necessary, in
Landlord's reasonable judgment, for Tenant's operations during Non-Business
Hours (it being understood and agreed that so long as Tenant leases all of the
Building, 100% of all expenses associated with operations during Non-Business
Hours shall be the responsibility of Tenant).  In addition, Tenant shall pay, as
additional rent, one hundred percent (100%) of any increase in Taxes not
otherwise billed to Tenant which may result from any alteration, addition or
improvement to the Premises that is made by or on behalf of Tenant.  Upon
request of Tenant, Landlord shall supply to Tenant reasonable evidence of such
increase in Taxes which shows that such increase is attributable to Tenant's
alteration, addition or improvement to the Premises.

          (b)  Before each Fiscal Year, Landlord shall give Tenant a reasonable
written estimate of the expected Operating Expenses and Taxes for the Property
for the coming Fiscal Year (excluding Landlord's cost for services provided
during Non-Business Hours), and a calculation of the estimated amount of
Tenant's Share of Expenses.  Tenant shall pay one-twelfth of the estimated
amount of Tenant's Share of Expenses with each monthly payment of Base Rent.
Within 120 days after the end of each Fiscal Year, Landlord shall give Tenant a
reasonably detailed written statement (the "Statement") showing the actual
Operating Expenses and Taxes for that Fiscal Year, a calculation of the actual
amount of Tenant's Share of Expenses, and a summary of amounts already paid by
Tenant pursuant to this Section 3.2.  If the actual amount of Tenant's Share of
Expenses for such Fiscal Year exceed Tenant's estimated payments on account of
Tenant's Share of Expenses for such Fiscal Year, Tenant shall pay such excess to
Landlord within thirty (30) days after delivery of the Statement to Tenant; if
such estimated payments exceed such actual amount of Tenant's Share of Expenses
Landlord shall pay such excess to Tenant at the time of the delivery of the
Statement to Tenant or, at Landlord's option, shall credit such excess against
the next payment of additional rent due on account of Operating Expenses from
Tenant under this Lease, and pay the remainder of such excess after such credit,
if any, to Tenant at the time of such next payment of additional rent, provided
that any excess shall be paid in cash to Tenant at the time of the delivery of
the Statement if the Term has ended.

                                      -7-
<PAGE>

No delay by Landlord in providing any Statement shall be deemed a waiver of
Tenant's obligation to pay Tenant's Share of Expenses.  Tenant and its auditors
shall have the right, upon notice to Landlord not less than ten (10) business
days in advance and then at a time reasonably convenient to both parties, to
inspect during usual business hours those portions of the books kept by Landlord
relating to costs and expenses for which Tenant has responsibility hereunder. If
Tenant disagrees with Landlord's determination of Operating Expenses and Taxes,
Tenant shall have the right to pay its share of Operating Expenses and Taxes
under protest without waiving its claim as to the disputed amount.

          (c)  The following terms used in this Section 3.2(c) shall have the
following meanings for purposes of this Lease:

               (i)  The term "Fiscal Year" means any twelve-month period
selected by Landlord for operating purposes. Landlord may change its Fiscal Year
and interim accounting periods, so long as the periods so revised are reconciled
with prior periods in accordance with generally accepted accounting principles.

               (ii) The term "Operating Expenses" means the total cost of
operation of the Property incurred by Landlord, including, without limitation:
(i) all costs of supplies, materials, equipment, and utilities used in or
related to the operation, maintenance, and repair of the Property or any part
thereof (excluding the cost of any electricity which is to be paid for
separately by Tenant pursuant to Section 3.3, but including the cost of
electricity if not paid separately by Tenant pursuant to Section 3.3); (ii) all
labor costs, including without limitation salaries, wages, payroll and other
taxes, unemployment insurance costs and employee benefits in connection with the
on-site management, operation and maintenance of the Property or any part
thereof; (iii) all maintenance, management, legal (excluding those legal costs
arising out of defaults of Landlord or other tenants in the Building, if any),
accounting, insurance, and service agreement costs related to the Property or
any part thereof; including, without limitation, service contracts with
independent contractors; and (iv) costs of improvements to the Property that are
designed to reduce Operating Expenses (but only to the extent that such costs
actually reduce Operating Expenses) or are required to comply with legal
requirements imposed after the initial completion of the Building (collectively,
"Permitted Capital Expenditures"), all such costs to be amortized (with interest
thereon at a rate two (2) percentage points above the then prevailing prime rate
as set by BankBoston, N.A. in its main office in Boston, MA (or, if such bank
ceases to exist, the then largest bank in the Commonwealth of Massachusetts))
over the useful life of such improvements according to generally accepted
accounting principles and the regulations under the Internal Revenue Code, and
only the annual amortized portion of such costs shall be included in Operating
Expenses for the Fiscal Year in which such costs are incurred and each
subsequent Fiscal Year until such costs are fully amortized. Any of the above
services may be performed by Landlord or its affiliates, provided that fees for
the performance of such services shall be reasonable and competitive with fees
charged by unaffiliated entities for the performance of such services in
comparable buildings in the area. Any other provision of this Lease
notwithstanding, . In the event that the Premises are reduced such that Tenant
does not lease 100% of the rentable area of the Building, all Operating Expenses
shall be adjusted based on the Calculation (as hereafter defined).
Notwithstanding any contrary provision of this Lease, Operating Costs shall not
include costs or expenses relating to the following:

                                      -8-
<PAGE>

               (a)  salaries, wages, wages, payroll and other taxes,
                    unemployment insurance costs, benefits and other expenses of
                    administrative employees and other employees involved in the
                    operation or management of the Property at or above the
                    level of building manager;

               (b)  any cost or expenses that Tenant incurs and pays directly;

               (c)  any costs payable directly by another tenant or any expenses
                    incurred by Landlord that are attributable to the operation
                    of the Building during Non-Business Hours (subject, however,
                    to Tenant's obligation to pay additional rent on account of
                    services provided during Non-Business Hours that are
                    requested by Tenant or necessary for Tenant's operations,
                    such obligation being set forth in Section 3.2(a) above)

               (d)  commercial concessions operated by Landlord;

               (e)  Landlord's general overhead;

               (f)  depreciation of the Property;

               (g)  principal, interest or other charges relating to
                    indebtedness secured by a mortgage covering any portion of
                    the Property, and payments of rent and other charges under
                    any ground lease or superior lease covering any portion of
                    the Property;

               (h)  leasehold improvements made in connection with the
                    preparation of any portion of the Property for occupancy by
                    a new or existing tenant;

               (i)  any expansion of the rentable area of the Property;

               (j)  repairs necessary to cure defects in the construction of any
                    portion or component of the Property (excluding structural
                    elements of the Building) during the term of any applicable
                    warranty, and repairs necessary to cure defects in the
                    construction of the structural elements of the Building
                    throughout the Term hereof;

               (k)  except as otherwise permitted above, any costs or expenses
                    that would be deemed a capital expenditure under generally
                    accepted accounting principles, except for Permitted Capital
                    Expenditures;

               (l)  repairs and replacements arising out of a fire or other
                    casualty (to the extent the cost therefor exceeds any
                    deductible payable under

                                      -9-
<PAGE>

                    Landlord's insurance policies) or an exercise of the eminent
                    domain affecting the Property;

               (m)  any items with respect to which Landlord actually receives
                    reimbursement from insurance proceeds or from a third party;

               (n)  efforts to lease portions of the Property or to procure new
                    tenants for the Property, including advertising expenses,
                    leasing commissions and attorney's fees;

               (o)  negotiations or disputes with any other tenant of the
                    Property;

               (p)  Landlord's breach or violation of a law, lease or other
                    obligation, including fines, penalties and attorneys' fees,
                    which breach or other violation is not caused by Tenant, its
                    employees, agents or invitees;

               (q)  any investigations, tests and evaluations of the presence,
                    nature or extent of any Hazardous Materials (as hereinafter
                    defined) on or about the Property and any efforts to
                    remediate any such Hazardous Materials or to bring the
                    Property into compliance with laws, regulations, codes,
                    orders and judgements related to Hazardous Materials, if the
                    presence of such Hazardous Materials was not caused by
                    Tenant, its employees, agents or invitees; and

               (r)  bringing the Property into compliance with laws existing as
                    of the date of this Lease, including without limitation the
                    Americans with Disabilities Act of 1990 and the regulations
                    and standards thereunder, provided that the foregoing shall
                    not derogate from Tenant's obligation to cause its Final
                    Plans for Leasehold Improvements and any other Alterations
                    to comply with all applicable laws, codes and regulations.

             (iii)  The term "Calculation" means that if less than 100% of the
rentable area of the Building is occupied in any Fiscal Year during the Term,
any components of Operating Expenses that vary with the degree of occupancy of
the Building shall be extrapolated to such expenses as Landlord would have
incurred if the Building had been 100% occupied, and the result shall constitute
the Operating Expenses for all purposes hereunder.  In addition, if during all
or part of any Fiscal Year, Landlord is not performing or furnishing any item or
service to any tenant other than Tenant (the cost of which, if performed or
furnished by Landlord to such other tenants, would constitute a part of
Operating Expenses), on account of (a) such item or service not being required
or desired by such tenant (other than Tenant), or (b) any tenant (other than
Tenant) obtaining or providing such item or service itself, then, Operating
Expenses shall be deemed to be increased by an amount equal to the additional
costs and expenses which

                                     -10-
<PAGE>

would reasonably have been incurred during such period by Landlord if it had
performed or furnished such item or service to all tenants of the Building.

               (iv)  The term "Taxes" means any form of assessment, rental tax,
license tax, business license fee, levy, charge, tax or similar imposition,
imposed by any authority having the power to tax, including any city, county,
state or federal government, or any school, agricultural, lighting, library,
drainage or other improvement or special assessment district, as against the
Property or any part thereof or any legal or equitable interest of Landlord
therein, or against Landlord by virtue of its interest therein, and any
reasonable costs incurred by Landlord in any proceeding for abatement thereof,
including, without limitation, attorneys' and consultants' fees; provided,
however, (a) Taxes shall not include any tax on Landlord's income, franchise
taxes, and assessments for off-site improvements, and (b) Landlord shall pay all
Taxes over the maximum time permitted by law, and Taxes for any Fiscal Year
shall include only those Taxes legally required to be paid in or allocable to
such Fiscal Year.  Landlord shall reimburse Tenant for Tenant's Share of any
abatements of Taxes received by Landlord, less legal, appraisal and other fees
and expenses incurred by Landlord in obtaining such abatement.

     3.3  Tenant's Electricity.
          --------------------

     Tenant agrees to pay all charges for electricity supplied to the Property
directly to the utility furnishing such electricity and, if requested by
Landlord, to provide Landlord with evidence of such payment.  In the event that
Landlord exercises its right to terminate this Lease with respect to any portion
of the Premises under Section 6.3(d) of this Lease or Tenant otherwise does not
lease 100% of the rentable area of the Building, all charges for electricity
supplied to the Property (including, without limitation, electricity supplied
during Non-Business Hours, except as otherwise set forth in Section 3.2 of this
Lease) shall be included within Operating Expenses and Tenant shall pay, as
additional rent, Tenant's share thereof in accordance with Section 3.2.

                                  ARTICLE IV
                                 CONSTRUCTION

     4.1  Building Construction.  Landlord, at its sole cost and expense, shall
          ---------------------
complete the construction, improvements, installations and other work
(collectively, the "Landlord's Work") necessary to construct the Building and
the Common Areas substantially in accordance with the plans and specifications a
schedule of which is attached to this Lease as Exhibit B (the "Base Building
Specifications") by a licensed contractor in a first-class workmanlike manner
and in compliance with all applicable laws, codes and regulations, including
without limitation the Americans with Disabilities Act of 1990, as amended.  Any
deviations from the Base Building Specifications which will materially and
adversely affect the design of the Leasehold Improvements or Tenant's use of the
Premises or the Property shall require Tenant's written approval, not to be
unreasonably withheld, conditioned or delayed, which approval shall be deemed
given if, within five (5) days after Landlord's written request for approval,
Tenant does not disapprove the same in writing and state the reasons therefor.

                                     -11-
<PAGE>

     4.2  Leasehold Improvements by Tenant.
          --------------------------------

          (a)  Tenant shall prepare plans and specifications (the "Preliminary
Plans") for the alterations, improvements and installations to the Building
desired by Tenant to prepare the Premises for Tenant's initial use and occupancy
("Leasehold Improvements") and deliver them to Landlord for its review and
approval, which approval shall not be unreasonably withheld, delayed or
conditioned.  The Preliminary Plans shall include complete architectural,
mechanical, electrical, plumbing and fire protection drawings in a form suitable
for submission for a building permit.  Within ten (10) days after delivery to
Landlord of the first Preliminary Plans and five days after delivery to Landlord
of any revisions to the Preliminary Plans, Landlord shall give notice to Tenant
of any changes or missing details Landlord reasonably believes are necessary to
bring the Final Plans into conformance with applicable law or Landlord's Work,
or to enable Tenant to construct the Leasehold Improvements without any
material, adverse effect on the roof, foundation, columns, exterior walls or
other structural components of the Building (collectively, the "Building's
Structure") or the heating, ventilation, air-conditioning, plumbing, electrical,
mechanical and other systems or equipment installed in the Building as part of
the Landlord's Work (the "Building's Systems").  Upon approval of the original
or revised Preliminary Plans (such approved Preliminary Plans being hereinafter
called the "Final Plans"), both parties shall approve them for filing.  In the
event of any conflict between the Base Building Specifications (as modified by
any deviations permitted under Section 4.1 above) and the Final Plans, the Base
Building Specifications (as so modified) shall control.  Tenant shall cause the
Leasehold Improvements to be constructed and installed in accordance with the
Final Plans by a licensed contractor in a first-class workmanlike manner and in
compliance with all applicable laws, codes and regulations (including, without
limitation, the Americans with Disabilities Act of 1990).  Tenant acknowledges
and agrees, notwithstanding Landlord's review and approval of the Preliminary
Plans and Final Plans, that Tenant shall be solely responsible for ensuring the
compliance of the Leasehold Improvements with such applicable laws, codes and
regulations, and that Landlord shall have no liability or responsibility to the
extent that the Preliminary Plans or Final Plans do not so comply.  Tenant shall
cause the Leasehold Improvements affecting the first and second floors of the
Building to be completed within one hundred twenty (120) days after the Premises
are Ready for Occupancy, and shall cause the remainder of the Leasehold
Improvements to be completed within one hundred eighty (180) days after the
Premises are Ready for Occupancy.  For purposes of the immediately preceding
sentence, the Leasehold Improvements shall be deemed complete when a permanent
certificate of occupancy has been issued for the space in question.  Tenant
shall be solely responsible for the cost of all Leasehold Improvements.  The
Leasehold Improvements, and all other work required or permitted to be performed
by Tenant hereunder, shall be designed and performed by architects, engineers
and contractors approved by Landlord, such approval not to be unreasonably
withheld.  For purposes of the immediately preceding sentence, Landlord hereby
approves Spagnolo/Gisness & Associates, Inc., as architect, Commercial
Construction Consulting, as engineer, and Aberthaw Construction Company, as
contractor.

          (b)  Tenant may make changes in the Final Plans after their approval,
subject to Landlord's prior approval, which shall not be unreasonably withheld,
delayed or conditioned; provided, however, that no such changes shall require or
cause a structural change in the Building, render the Premises or the Building
in violation of applicable laws, cause any material,

                                     -12-
<PAGE>

adverse impact on the roof, foundation, columns, exterior walls or other
structural components of the Building or the heating, ventilation, air-
conditioning, plumbing, electrical, mechanical and other systems or equipment
installed in the Building as part of the Landlord's Work.

     4.3  Alterations by Tenant.
          ---------------------

          (a)  Tenant shall not make any alterations, additions, installations,
substitutes or improvements (hereinafter collectively called "Alterations") in
and to the Premises, without first obtaining Landlord's written consent, which
consent shall not be unreasonably withheld, delayed or conditioned; provided,
however, Tenant shall have the right, without Landlord's prior consent, to
complete alterations, additions, installations, substitutes or improvements
which (x) do not cost more than $25,000 in any single instance, (y) do not have
any effect on the Building's Structure, and (z) do not have any adverse effect
on the Building's Systems (collectively, "Exempt Alterations").  No Alteration
shall violate the certificate of occupancy for the Premises or any applicable
law, code or ordinance or affect the exterior appearance of the Building,
adversely affect the Building's Structure, adversely affect any other part of
the Building's Systems or, without the Landlord's prior written consent, which
shall not be unreasonably withheld, delayed or conditioned in the case of items
which are not fixtures, involve the installation of any materials subject to any
liens or conditional sales contracts (the "Approval Review Matters").  Tenant
shall pay Landlord's reasonable costs of reviewing or inspecting any proposed
Alterations.

          (b)  All work on any Alterations shall be done in a first-class
workmanlike manner, by contractors reasonably approved by Landlord, and, except
for Exempt Alterations, according to plans and specifications approved by
Landlord, which approvals shall not be unreasonably withheld, delayed or
conditioned.  All work shall be done in compliance with all applicable laws,
regulations, and rules of any government agency with jurisdiction, and with all
regulations of the Board of Fire Underwriters or any similar insurance body or
bodies.  Tenant shall be solely responsible for the effect of any Alterations on
the Building's structure and systems, whether or not Landlord has consented to
the Alterations, and shall reimburse Landlord on demand for any costs incurred
by Landlord by reason of any faulty work done by Tenant or its contractors.
Upon completion of any Alterations, Tenant shall provide Landlord with a
complete set of "as-built" plans.

          (c)  Tenant shall use its best efforts to keep the Property and
Tenant's leasehold interest therein free of any liens or claims of liens and
shall discharge or bond any such liens (i) within ten (10) days of their filing,
in the case of liens arising from Alterations and (ii) within thirty (30) days
of their filing, in the case of all other liens arising from acts or negligence
of Tenant, or its subtenants, contractors or others claiming by, through or
under Tenant.  Before commencement of any Alterations costing more than $250,000
(excluding the Leasehold Improvements), Tenant's contractor shall provide any
payment, performance and lien indemnity bond reasonably requested by Landlord.
Tenant shall provide evidence of such insurance as Landlord may reasonably
require, naming Landlord as an additional insured.  Tenant shall indemnify
Landlord and hold it harmless from and against any cost, claim, or liability
arising from any Alterations done by or at the direction of Tenant.  All work
shall be done so as to minimize interference with other tenants, if any, and
with Landlord's operation of the Building or other construction work being done
by Landlord.  Landlord may post any notices it considers

                                     -13-
<PAGE>

necessary to protect it from responsibility or liability for any Alterations,
and Tenant shall give sufficient notice to Landlord to permit such posting.

          (d)  All Alterations affixed to the Premises shall become part thereof
and remain therein at the end of the Term, except (i)Tenant's trade fixtures,
(ii) any Alterations that Tenant reserves the right to remove by written notice
to Landlord at the time Tenant requests Landlord's consent to such Alterations,
and (iii) Exempt Alterations which, prior to their installation, Tenant reserved
the right to remove by written notice to Landlord. However, if Landlord informs
Tenant upon the approval of any such Alterations (or in the case of Exempt
Alterations, at any time within 30 days after the expiration or early
termination of this Lease) that such Alterations or Exempt Alterations as the
case may be (other than the Leasehold Improvements) must be removed at the end
of the Term, Tenant shall do so at the end of the Term and shall pay the cost of
removal and any repair required by such removal.

               All of Tenant's personal property, trade fixtures, equipment,
furniture, movable partitions, and any Alterations not affixed to the Premises
shall remain Tenant's property, removable at any time.  If Tenant fails to
remove any such materials (or any other Alterations which Tenant is required to
remove) at the end of the Term, Landlord may do so and store them at Tenant's
expense, without liability to Tenant, and may sell them at public or private
sale and apply the proceeds to any amounts due hereunder, including costs of
removal, storage and sale.

                                   ARTICLE V
                       LANDLORD'S OBLIGATIONS AND RIGHTS

     5.1  Services Furnished by Landlord.
          ------------------------------

          (a)  Landlord shall furnish space heating, ventilation and cooling as
normal seasonal changes may require to provide reasonably comfortable space
temperature and ventilation for occupants of the Premises under normal business
operations.

          (b)  Subject to the provisions of Section 3.3, Landlord shall provide
electric power for lighting and office machine use under normal business
operation.  Tenant's use of electrical energy in the Premises shall not at any
time exceed the capacity of any of the electrical conductors or equipment in or
otherwise serving the Premises.  In order to ensure that such capacity is not
exceeded and to avert possible adverse effect upon the Building electric
service, Tenant shall not, without prior consent of Landlord in each instance
(which consent shall not be unreasonably withheld or delayed), make any
alteration or addition having any adverse effect on the electric system of the
Premises or requiring any changes in the Building's electrical room.

          (c)  In the event that Landlord exercises its right to terminate this
Lease with respect to any portion of the Premises under Section 6.3(d) of this
Lease or Tenant does not otherwise lease 100% of the rentable area of the
Building, Landlord shall furnish services, utilities, facilities and supplies to
the Common Areas located within the Building equal in quality to those
customarily provided by landlords in high quality office buildings of a
comparable design in the greater Boston suburban area, including without
limitation cleaning and janitorial

                                     -14-
<PAGE>

services, the cost of such services, utilities, facilities and supplies to be
included within Operating Expenses, subject to the provisions of Section 3.2
above.

     5.2  Repairs and Maintenance.
          -----------------------

Landlord shall perform all maintenance, repairs and replacements necessary to
keep the Building's Structure, the Building's Systems, the Common Areas
(including without limitation removal of snow and ice from walkways, driveways,
parking areas and loading areas), all landscaping on the Property, and all
retention ponds and other improvements and facilities providing drainage for the
benefit of the Property, in good condition and working order and in compliance
with all applicable laws, except for damage resulting from a casualty or an
eminent domain taking, which shall be governed by Article VIII. If any
maintenance, repair or replacement is required because of any act or negligence
of Tenant or its agents, employees, invitees or contractors, the cost thereof
shall be paid by Tenant to Landlord as additional rent within thirty (30) days
after billing therefor.

     5.3  Quiet Enjoyment.
          ---------------

Upon Tenant's paying the rent and performing its other obligations, Landlord
shall permit Tenant to peacefully and quietly hold and enjoy the Premises,
subject to the provisions of this Lease.

     5.4  Insurance.
          ---------

Landlord shall carry the following insurance during the Term:  (a) a policy of
insurance covering the Building and the Property for all direct risk of physical
loss (including so-called "all-risk" coverage and "extended coverage" and
coverage for fire, vandalism and malicious mischief) in an amount not to exceed
the full replacement value, and (b) a policy general commercial liability
insurance with limits of $2,000,000 per occurrence and $4,000,000 in the general
aggregate, naming Tenant as an additional insured, and (c) during construction,
builders risk insurance. Landlord may carry any other forms of insurance as it
or its mortgagee may reasonably deem advisable.  Landlord shall not carry any
insurance on any of Tenant's trade fixtures or personal property, and shall not
be obligated to repair or replace any of Tenant's trade fixtures or personal
property.

     5.5  Access to Premises.
          ------------------

Landlord shall have reasonable access to the Premises to inspect Tenant's
performance hereunder and to perform any acts required of or permitted to
Landlord herein.  Landlord shall at all times have a key or access card to the
Premises.  Any entry into the Premises by Landlord, under this Section 5.5 or
any other section of this Lease permitting such entry, shall be on reasonable
advance notice, shall be done so as not to unreasonably interfere with Tenant's
use of the Premises, and shall be accompanied by a representative of Tenant if
Tenant so requests; provided, however, that such restrictions shall not apply to
any situation that Landlord in good faith believes to be an emergency.

                                     -15-
<PAGE>

     5.6  Right to Cease Providing Services.
          ---------------------------------

In connection with any repairs, alterations or additions to the Property or the
Premises, or any other acts required of or permitted to Landlord herein, or in
the event of Force Majeure (as hereinafter defined), Landlord may, if necessary,
reduce or suspend service of the Building's utilities and mechanical systems, or
any of the other services, facilities or supplies required to be provided by
Landlord hereunder, provided that (a) Landlord shall use best efforts to restore
such services, facilities or supplies as soon as possible, (b) Landlord shall
give Tenant advance notice of any such reduction or suspension if such reduction
or suspension is planned in advance or if it is reasonably possible for Landlord
to do so, (c) in connection with any repairs or other acts required of Landlord
under this Lease or Force Majeure, Landlord shall use reasonable efforts to
minimize any interference with Tenant's use and enjoyment of the Premises and
the Common Areas, and (d) in connection with any alterations, additions or other
acts permitted (but not required) under this Lease, Landlord shall not
materially interfere with Tenant's use and enjoyment of the Premises and the
Common Areas. No such reduction or suspension permitted by this Section 5.6
shall constitute an actual or constructive eviction or disturbance of Tenant's
use or possession of the Premises, or an ejection of Tenant from the Premises,
or a breach by Landlord of any of its obligations, and no such reduction or
suspension shall render Landlord liable for any damages, including but not
limited to any damages, compensation or claims arising from any interruption or
cessation of Tenant's business, or entitle Tenant to be relieved from any of its
obligations under this Lease, or result in any abatement or reduction of rent.

     5.7  Failure to Provide Services and Repairs.
          ---------------------------------------

          (a)  Landlord shall not be in default or liable for any failure to
perform any act or obligation or provide any service required hereunder unless
Tenant shall have given notice of such failure, and such failure continues for
thirty (30) days thereafter; provided, however, that if the nature of Landlord's
obligation is such that more than thirty (30) days are required for its
performance, then Landlord shall not be liable or in default if it commences
such performance within thirty (30) days and thereafter diligently pursues such
performance to completion.  If Landlord is in default hereunder (after the
expiration of the aforesaid period), then upon ten (10) days written notice
given by Tenant to Landlord and to the holder of any Mortgage (whose address has
been provided to Tenant by Landlord), Tenant shall have the right to spend up to
Fifty Thousand Dollars ($50,000.00) to cure such failure on Landlord's behalf,
and Landlord shall reimburse to Tenant, within 30 days after Landlord receives a
written demand from Tenant, any sums expended by Tenant in effecting such cure
up to the aforesaid maximum of Fifty Thousand Dollars ($50,000.00).  In no event
shall Tenant have the right to off-set the amounts so incurred by Tenant against
payments of Base Rent or additional rent payable by Tenant under this Lease.

                                  ARTICLE VI
                              TENANT'S COVENANTS

     6.1  Repair and Yield Up.
          -------------------

Subject to Landlord's obligations under Section 5.2 of this Lease, Tenant shall
keep the Premises in as good order and condition as the Premises exists on the
Commencement Date or such

                                     -16-
<PAGE>

improved order and condition as exists after the completion of the Leasehold
Improvements or any Alterations, except for reasonable wear and tear and damage
from fire, other casualty and eminent domain. At the end of the Term, Tenant
shall peaceably yield up the Premises in such order and condition. Tenant shall
remove its trade fixtures and personal property and any Alterations which Tenant
is required to remove under the terms hereof, repairing any damage caused by
such removal and leaving the Premises clean and neat. Nothing herein shall
require Tenant to remove the Leasehold Improvements.

     6.2  Use.
          ---

          (a)  Tenant shall use the Premises only for the Permitted Uses, and
shall not use or permit the Premises to be used for any other purpose.  Tenant
shall not use or occupy the Premises in violation of (i) any law or ordinance or
any certificate of occupancy issued for the Building or the Premises, or (ii)
any Rules and Regulations.  Tenant shall comply with any directive of any
governmental authority with respect to Tenant's use or occupancy of the
Premises.  Tenant shall not do or permit anything in or about the Premises which
will in any way damage the Premises, obstruct or interfere with the use and
occupancy of the Property by other tenants or occupants of the Building, if any,
or injure them, or use the Premises or allow them to be used for any unlawful
purpose.  Tenant shall not cause, maintain or permit any nuisance in, on or
about the Premises, or commit or allow any waste in or upon the Premises.

          (b)  Tenant shall not obstruct any of the Common Areas or any portion
of the Property outside the Premises, and shall not place or permit any signs
(other than those permitted under Section 6.2(c)), awnings, aerials or
flagpoles, or the like, visible from outside the Premises.

          (c)  Notwithstanding the foregoing, Tenant shall have the right, at
its sole expense, to install a sign on the exterior of the Building, provided
however that such sign complies with all applicable laws, and provided further
that Tenant obtains Landlord's prior written consent to such sign (including,
without limitation, the size, design and location of such sign), such consent
not to be unreasonably withheld, delayed or conditioned.  Tenant shall be
responsible for obtaining all permits and other governmental approvals required
for such sign.

          (d)  Tenant shall keep the Premises equipped with all safety
appliances required by law because of any use made by Tenant other than office
use with customary office equipment, and shall procure all licenses and permits
required because of such use.  This provision shall not broaden the Permitted
Uses.

          (e)  Tenant shall not place a load upon the floor of the Premises
exceeding 100 pounds per square foot.  Partitions shall be considered as part of
the load.  Tenant shall properly distribute the weight and position of all
safes, files and heavy equipment.  Tenant's business machines and mechanical
equipment shall be installed and maintained so as not to transmit noise or
vibration to the Building structure or to any other space in the Building.
Tenant shall be responsible for the cost of all structural engineering required
to determine structural load and all acoustical engineering required to address
any noise or vibration caused by Tenant.

                                     -17-
<PAGE>

          (f)  Tenant shall not keep or use any article in the Premises, or
permit any activity therein, which is prohibited by a standard insurance policy
covering buildings and improvements similar to the Building and Leasehold
Improvements, or would result in an increase in the premiums thereunder, unless
Tenant pays for such increase.  In determining whether increased premiums are a
result of Tenant's activity, a schedule issued by the organization computing the
insurance rate on the Building or the Leasehold Improvements, showing the
various components of the rate, shall be conclusive evidence.  Tenant shall
promptly comply with all reasonable requirements of the insurance authority or
of any insurer relating to the Premises.  If the use or occupation of the
Premises by Tenant or by anyone Tenant allows on the Premises causes or
threatens cancellation or reduction of any insurance carried by Landlord, Tenant
shall remedy the condition immediately upon notice thereof.  Upon Tenant's
failure to do so, Landlord may, in addition to any other remedy it has under
this Lease but subject to the provisions of Section 5.5, enter the Premises and
remedy the condition, at Tenant's cost, which Tenant shall promptly pay as
additional rent.  Landlord shall not be liable for any damage or injury caused
as a result of such an entry, and shall not waive its rights to declare a
default (or Event of Default) because of Tenant's failure.

     6.3  Assignment; Sublease.
          --------------------

          (a)  Tenant shall not assign, mortgage, pledge or otherwise transfer
this Lease or make any sublease of the Premises, or permit occupancy of any part
thereof by anyone other than Tenant (any such act being referred to herein as a
"Transfer" and the other party with whom Tenant undertakes such act being
referred to herein as a "Transferee") without the prior written consent of
Landlord, which consent shall not be unreasonably withheld or delayed, subject
to the other provisions of this Section 6.3.  Any Transfer or attempted Transfer
not in compliance with all of the terms and conditions set forth in this Section
6.3 shall be void.

          (b)  Any request by Tenant for Landlord's consent to a Transfer shall
include the name of the proposed Transferee, the nature of its business and
proposed use of the Premises, reasonable information as to its financial
condition, and the terms and conditions of the proposed Transfer.  Tenant shall
supply such additional information about the proposed Transfer and Transferee as
the Landlord reasonably requests.  Subject to paragraph (g) below, it shall be
reasonable for Landlord to refuse consent to any Transfer to any governmental
agency or to any Transferee whose tangible net worth and financial strength is
not reasonably satisfactory to Landlord in light of the terms of the Transfer.
Provided Tenant has promptly supplied all required information to Landlord,
Landlord shall respond to Tenant's request within ten (10) days of its receipt
of such request, and the failure of Landlord to respond within said ten (10)
days shall be deemed to be approval of the Transfer by Landlord, provided that
the request for consent from Tenant shall specifically refer to the provisions
of this sentence.  Tenant shall reimburse Landlord for its reasonable legal
expenses in connection with any request for consent.

          (c)  Any Transfer shall specifically make applicable to the Transferee
all of the provisions of this Section so that Landlord shall have against the
Transferee all rights with respect to any further Transfer which are set forth
herein.  No Transfer shall affect the continuing primary liability of Tenant
(except that such liability shall be joint and several with any assignee of this
Lease).  Consent to a Transfer in a specific instance shall not be deemed
consent to any subsequent Transfer or a waiver of the requirement of consent to
any future Transfer.  No

                                     -18-
<PAGE>

Transfer shall be binding upon Landlord or any of Landlord's mortgagees, unless
Tenant shall deliver to Landlord a recordable instrument containing a covenant
of assumption by the Transferee running to Landlord and all persons claiming by,
through or under Landlord.  The Transferee's failure to execute such instrument
shall not, however, release or discharge Transferee from its liability as a
Transferee hereunder.  Tenant shall not enter into any Transfer that provides
for rental or other payment based on the net income or profits derived from the
Premises.  With respect to any Transfer, Landlord shall be entitled to receive
fifty percent (50%) of all "Bonus Rent," which Bonus Rent shall be payable by
Tenant to Landlord on a monthly basis.  For purposes of this Lease, Bonus Rent
shall mean all rent and other consideration attributable to Tenant's interests
in the Premises and under this Lease received by Tenant in excess of the Base
Rent, additional rent and other sums payable by Tenant to Landlord under this
Lease, prorated according to the fraction of the Rentable Square Feet in the
Premises that is affected by such Transfer, for the period of the Transfer,
minus (x) Tenant's reasonable expenses in connection with such Transfer for
brokerage commissions, legal fees, advertising expenses and Alterations for the
benefit of the Transferee and (y) the unamortized portion of the expenses
incurred by Tenant in connection with the Leasehold Improvements, which expenses
shall be amortized on a straight-line basis over the balance of the Term
remaining as of the completion of such Leasehold Improvements or Alterations.

          (d)  If Tenant requests Landlord's consent to a proposed Transfer, (x)
Landlord shall have an option to cancel and terminate this Lease if Tenant
requests Landlord's consent to assign the Lease or to sublet all of the Premises
for the balance of the Term; or (y) if the request is to sublet a portion of the
Premises such that, when such portion is combined with all portions of the
Premises previously sublet by Tenant, Tenant will be subletting more than
fifteen percent (15%) of the Rentable Square Feet in the Premises, Landlord
shall have the option to cancel and terminate this Lease with respect to the
portion for which Landlord's consent is sought (the "Recaptured Space").  For
purposes of illustration only, if Tenant has previously sublet twelve percent
(12%) of the Rentable Square Feet in the Premises and subsequently requests
Landlord's consent to sublet an additional five percent (5%) of the Rentable
Square Feet in the Premises, Landlord shall have the option to terminate this
Lease with respect to the additional five percent (5%) portion of the Premises,
and if Tenant subsequently requests Landlord's consent to sublet any portion of
the Premises thereafter (regardless of the size of such portion), Landlord shall
have the further option to terminate this Lease with respect to such additional
portion (regardless of whether it has previously exercised any recapture right).
Landlord shall exercise the aforesaid option by written notice to Tenant within
thirty (30) days after Landlord's receipt from Tenant of any request for
Landlord's consent to such assignment or sublease, and in such case such
cancellation or termination shall occur as of the date set forth in Landlord's
notice of exercise of such option, which shall not be less than sixty (60) days
nor more than one hundred twenty (120) days following the giving of such notice.
If Landlord exercises Landlord's option to cancel this Lease or any portion
thereof, Tenant shall surrender possession of the Premises, or the portion
thereof which is the subject of the option, as the case may be, on the date set
forth in such notice in accordance with the provisions of this Lease relating to
surrender of the Premises at the expiration of the Term.  If this Lease is
cancelled as to a portion of the Premises only, (a) the Rentable Square Feet in
the Premises shall be the rentable area of the Premises (excluding the Interior
Common Areas , areas containing the Building's Systems and the Recaptured Space)
calculated by an architect, reasonably acceptable to Landlord

                                     -19-
<PAGE>

and Tenant, in accordance with the American National Standard Method for
Measuring Floor Area in Office Buildings, ANSI Z65.1-1980, published by the
Building Owner's and Manager's Association, (b) the Tenant's Percentage and the
Base Rent shall be reduced in portion to the reduction in the Rentable Square
Feet in the Premises, and (c) before any tenant is permitted to occupy or use
any Recaptured Space, Landlord, at its sole expense and without material
interference with Tenant's use and enjoyment of the remainder of the Premises,
shall construct all walls necessary to separate the Recaptured Space from the
remainder of the Premises, all entrances, lobbies and corridors necessary to
provide access to the Recaptured Space without passing through any portion of
the remainder of the Premises and, if the Recaptured Space comprises less than a
full floor of the Building, common rest rooms on such floor (the "Interior
Common Areas"), and all pipes, wires, ducts, conduits and other systems and
equipment necessary to provide heating, ventilation, air-conditioning,
electricity, plumbing, telecommunications and other utilities and services to
the Recaptured Space and the Interior Common Areas (the "Recaptured Utilities").
If Landlord does not exercise Landlord's option to cancel this Lease with
respect to all or any portion of the Premises pursuant to the foregoing
provisions, Landlord's consent to a Transfer shall continue to be required in
accordance with the other provisions of this Section 6.3.

          (e)  Any agreement by which Tenant agrees to enter into or execute any
Transfer at the direction of any other party, or assigns its rights in the
income arising from any Transfer to any other party, shall itself constitute a
Transfer hereunder.

          (f)  Tenant shall have no right to assign this Lease or sublet all or
any portion of the Premises, and any such assignment or sublease shall, at
Landlord's option, be void, unless on both (i) the date on which Tenant notifies
Landlord of its intention to enter into any assignment or sublease and (ii) the
date on which such assignment or sublease is to take effect, Tenant is not in
default of any of its obligations under this Lease after notice to Tenant and
expiration of applicable grace periods.

          Notwithstanding any other provision of this Lease, Tenant shall have
the right, without Landlord's prior written consent, without the obligation to
pay any Bonus Rent to Landlord, and without Landlord having any right to cancel
or terminate this Lease, to assign this Lease or to sublet all or any portion of
this Lease, from time to time, to any person or business organization (x)
acquiring, whether in one transaction or a series, all or substantially all of
the equity interests in Tenant, or (y) with or into which Tenant merges or
consolidates, provided however that in the event of a Transfer described in (x)
or (y) above, notwithstanding any provision of Section 10.19 to the contrary
permitting a reduction in the principal amount of the Letter of Credit or the
return of the Letter of Credit to Tenant prior to the expiration of the Term of
this Lease, the Tenant hereunder shall be required to maintain with Landlord,
throughout the Term hereof, a security deposit (which security deposit may be in
the form of a letter of credit otherwise complying with the requirements of
Section 10.19) in the amount of Five Hundred Thousand Dollars ($500,000.00).
Notwithstanding the immediately preceding sentence, in the event that the
acquiring person or entity described in clause (x) above, or the surviving
entity described in clause (y) above, as the case may be, assumes all of
Tenant's obligations under this Lease in a written instrument reasonably
satisfactory to Landlord, and such person or entity has a net worth and
financial strength at least equivalent to that of Tenant immediately prior to
such Transfer, then the Tenant hereunder shall not be required to maintain the
Letter of Credit or

                                     -20-
<PAGE>

security deposit except as provided in Section 10.19 below. Furthermore, any
other provision of this Lease notwithstanding, Tenant shall have the right,
without Landlord's prior written consent, without the obligation to pay any
Bonus Rent to Landlord, and without Landlord having any right to cancel or
terminate this Lease, to assign this Lease or to sublet all or any portion of
this Lease, from time to time, to any person or business organization (i)
controlled by Tenant, (ii) controlling or under common control with Tenant
(provided that, in connection with such person or business organization
acquiring control of Tenant, the provisions of the two immediately preceding
sentences have been complied with) or (iii) acquiring all or substantially all
of the assets of Tenant, provided that such Transferee acquiring all or
substantially all of the assets of Tenant has a net worth and financial
strength, after such acquisition, at least equivalent to that of Tenant
immediately prior to such Transfer, and provided further that Tenant shall not
transfer all or substantially all of its assets without also assigning this
Lease to such transferee.

     6.4  Indemnity; Assumption of Risk.
          -----------------------------

          (a)  Tenant, at its expense, shall defend (with counsel reasonably
satisfactory to Landlord), indemnify and hold harmless Landlord and its
management agent, and their respective employees, , from and against any cost,
claim, action, liability or damage of any kind to the extent arising from (i)
Tenant's use and occupancy of the Premises and the Property or any activity done
by Tenant or its agents, employees, contractors or invitees in, on or about the
Premises or the Property, (ii) the destruction of or damage to Tenant's personal
property, (iii) any breach or default by Tenant of its obligations under this
Lease, or (iv) any negligent, tortious, or illegal act or omission of Tenant,
its agents, employees, invitees, licensees or contractors, provided that such
cost, claim, action, liability or damage is not caused by the negligence or
willful misconduct of Landlord or its agents, employees, invitees, licensees and
contractors (except as otherwise provided in the last sentence of subsection
6.5(a)).

          (b)  As a material consideration to Landlord for executing this Lease,
Tenant assumes all risk of damage or injury to any property of Tenant, its
employees, invitees or any person in or about the Premises, including without
limitation damage caused by or resulting from fire, steam, electricity, gas,
water or rain which may leak or flow from or into any part of the Premises, or
from the breakage, leakage, obstruction, or other defects of pipes, sprinklers,
wires, appliances, plumbing, air-conditioning or lighting fixtures, whether such
damage or injury results from conditions arising upon the Premises, any other
portion of the Property, or other sources, provided that such damage or injury
is not caused by the negligence or willful misconduct of Landlord or its agents,
employees, invitees, licensees and contractors (except as otherwise provided in
the last sentence of subsection 6.5(a)).  Landlord shall not be liable to Tenant
or any other person or entity for any damages arising from any act or omission
of any other tenant of the Building.

     6.5  Tenant's Insurance.
          ------------------

          (a)  Tenant shall maintain the following insurance at its own expense
throughout the Term:  (i) a policy of insurance covering Tenant's trade fixtures
and personal property in or about the Premises for all direct risk of physical
loss (including so-called "all-risk" coverage and "extended coverage" and
coverage for fire, vandalism and malicious mischief), in an amount not less than
full replacement cost thereof;  and (ii) a policy of commercial general

                                     -21-
<PAGE>

liability insurance, which insurance may be by a blanket insurance policy,
insuring Tenant, including coverage for injuries to persons and damage to
property assumed by Tenant under this Lease, and naming Landlord as an
additional insured, in limits not less than Two Million Dollars ($2,000,000.00)
per occurrence and Four Million Dollars ($4,000,000.00) in the general
aggregate, with a deductible not to exceed One Hundred Thousand Dollars
($100,000.00). Tenant acknowledges and agrees that such property owned by Tenant
shall be at the sole risk and hazard of Tenant, and if the whole or any part
thereof shall be destroyed or damaged by fire, water or otherwise, or by the
leakage or bursting of water pipes, steam pipes, or other pipes, by theft or
from any other cause, no part of said loss or damage is to be charged to or be
borne by Landlord regardless of any fault of Landlord.

          (b)  All policies shall (i) be taken out with insurers reasonably
acceptable to Landlord, in form reasonably satisfactory to Landlord, and (ii)
include Landlord and any mortgagee of Landlord of which Tenant has received
written notice as additional insureds, as their interests may appear.  Tenant
shall provide certificates of insurance in form satisfactory to Landlord before
the Commencement Date, and shall provide certificates evidencing renewal at
least ten (10) days before the expiration of any such policy.  All policies
shall contain an endorsement requiring at least thirty (30) days' prior written
notice to Landlord and any mortgagee of Landlord of which Tenant has received
written notice prior to any material change, reduction, cancellation or other
termination.

          (c)  Upon termination of this Lease pursuant to any casualty, Tenant
shall retain any proceeds attributable to Tenant's personal property, trade
fixtures, movable partitions, equipment and Alterations not affixed to the
Premises, but Tenant shall immediately pay to Landlord any insurance proceeds
received by Tenant relating to the Leasehold Improvements and any Alterations
affixed to the Premises which Tenant is not required or permitted to remove
under this Lease.

     6.6  Right of Entry.
          --------------

Subject to the provisions of Sections 5.5 and 5.6 hereof, Tenant shall permit
Landlord and its agents to examine the Premises at reasonable times, to make any
repairs or replacements Landlord required or permitted under this Lease,
provided that Landlord shall not materially interfere with Tenant's use and
enjoyment of the Premises, except in the case of emergencies and maintenance,
repairs and replacements required of Landlord under this Lease, with respect to
which Landlord shall use reasonable efforts to minimize interference with
Tenant's normal activities; to remove, at Tenant's expense, after reasonable
notice to Tenant (except in the case of an emergency in which no notice shall be
required), any Alterations, except for Exempt Alterations, not consented to by
Landlord; and to show the Premises to prospective tenants during the last twelve
(12) months of the Term and to prospective purchasers and mortgagees at all
times.

     6.7  Payment of Taxes.
          ----------------

Tenant shall pay before delinquency all taxes levied against Tenant's personal
property or trade fixtures in the Premises and any Alterations installed by or
on behalf of Tenant.  If any such taxes are levied against Landlord or its
property, or if the assessed value of the Premises is

                                     -22-
<PAGE>

increased by the inclusion of a value placed on Tenant's property, Landlord may
pay such taxes, and Tenant shall upon demand repay to Landlord the portion of
such taxes resulting from such increase. Tenant may bring suit against the
taxing authority to recover the amount of any such taxes, and Landlord shall
cooperate therein. The records of the Town Assessor shall determine the assessed
valuation, if available and sufficiently detailed. If not so available or
detailed, the actual cost of construction shall be used.

     6.8  Environmental Compliance.
          ------------------------

          (a)  Tenant shall not cause any hazardous or toxic wastes, hazardous
or toxic substances or hazardous or toxic materials (collectively, "Hazardous
Materials"), other than (i) ordinary office supplies and cleaning substances and
(ii) other Hazardous Materials used in the ordinary course of Tenant's business,
provided that such Hazardous Materials are not used, generated, stored or
disposed of at levels which require disclosure or reporting to any governmental
authority (collectively, "Permitted Substances"), to be used, generated, stored
or disposed of on, under or about, or transported to or from, the Premises
(collectively, "Hazardous Materials Activities") without first receiving
Landlord's written consent, which may be withheld for any reason and revoked at
any time.  Tenant shall use, generate, store and dispose of all Permitted
Substances and, if Landlord consents to any such Hazardous Materials Activities,
shall conduct such Hazardous Materials Activities in strict compliance (at
Tenant's expense) with all applicable Regulations, as hereinafter defined, and
using all necessary and appropriate precautions.  Landlord shall not be liable
to Tenant for any Hazardous Materials Activities by Tenant, Tenant's employees,
agents, contractors, licensees or invitees, whether or not consented to by
Landlord.  Tenant shall indemnify, defend with counsel acceptable to Landlord
and hold Landlord harmless from and against any claims, damages, costs and
liabilities arising out of the use, generation, storage and disposal of
Permitted Substances and Tenant's Hazardous Materials Activities.  For purposes
hereof, Hazardous Materials shall include but not be limited to substances
defined as "hazardous substances," "toxic substances," or "hazardous wastes" in
the federal Comprehensive Environmental Response, Compensation and Liability Act
of 1980, as amended; the federal Hazardous Materials Transportation Act, as
amended; and the federal Resource Conservation and Recovery Act, as amended
("RCRA"); those substances defined as "hazardous wastes" in the Massachusetts
Hazardous Waste Facility Siting Act, as amended (Massachusetts General Laws
Chapter 21D); those substances defined as "hazardous materials" or "oil" in
Massachusetts General Laws Chapter 21E, as amended; and as such substances are
defined in any regulations adopted and publications promulgated pursuant to said
laws (collectively, "Regulations").  Annually, during the first month of each
calendar year, Tenant shall provide Landlord with a list of the types and
quantities of any Hazardous Materials used or stored on the Premises.  Tenant
shall also provide Landlord with a copy of any Hazardous Materials inventory
statement required to be filed with any governmental authority under any
applicable Regulations, and any update filed in accordance with any applicable
Regulations.  If Tenant's activities violate or create a risk of violation of
any Regulations, Tenant shall cease such activities immediately upon notice from
Landlord.  Tenant shall immediately notify Landlord both by telephone and in
writing of any spill or unauthorized discharge of Hazardous Materials or of any
condition constituting an imminent hazard under any Regulations.  Upon
reasonable advance notice, subject to Section 5.5 of this Lease, Landlord,
Landlord's representatives and employees may enter the Premises at any time
during the Term to inspect

                                     -23-
<PAGE>

Tenant's compliance herewith, and may disclose any violation of any Regulations
to any governmental agency with jurisdiction.

          (b) Except as disclosed in that certain report entitled "Phase II
Environmental Work, 100 Apollo Drive," dated June 1, 1998 and prepared by GZA
Geoenvironmental, Inc., Landlord represents and warrants to the best of its
knowledge that there are no Hazardous Materials on or about the Property.

     6.9  Utilities.

Tenant shall pay all charges for all separately metered and separately billed
gas, telephone and other utility services used, rendered or supplied upon or in
connection with the Premises, and shall indemnify Landlord against any liability
or damage on such account.  Payment of charges for electricity is provided for
under Section 3.3 hereof.

                                  ARTICLE VII
                                    DEFAULT

     7.1  Events of Default.
          -----------------

          (a)  The occurrence of any one or more of the following events shall
constitute an "Event of Default":

               (i)   The failure by Tenant to make any payment of Base Rent or
additional rent or any other payment required hereunder, as and when due, where
such failure shall continue for a period of five (5) business days after written
notice thereof from Landlord to Tenant.

               (ii)  The abandonment of the Premises by Tenant.

               (iii) The failure by Tenant to perform any of its obligations
under this Lease, other than as specified in clauses (i) and (ii) above, where
such failure shall continue for a period of more than thirty (30) days after
written notice thereof from Landlord to Tenant; provided, however, that if the
nature of Tenant's failure is such that more than thirty (30) days are
reasonably required for its cure, then Tenant shall not be deemed to be in
default if Tenant shall commence such cure within said thirty-day period and
thereafter diligently prosecute such cure to completion, which completion shall
occur not later than ninety (90) days from the date of such notice from
Landlord.

               (iv)  The failure by Tenant to pay its debts as they become due,
or Tenant becoming insolvent, filing or having filed against it a petition under
any chapter of the United States Bankruptcy Code, 11 U.S.C. Section 101 et seq.
(or any similar petition under any insolvency law of any jurisdiction),
proposing any dissolution, liquidation, composition, financial reorganization or
recapitalization with creditors, making an assignment or trust mortgage for the
benefit of creditors, or if a receiver, trustee, custodian or similar agent is
appointed or takes possession with respect to any property or business of
Tenant, it being understood and agreed that in cases where such petition or
appointment was involuntarily filed or

                                     -24-
<PAGE>

made, no Event of Default shall occur unless Tenant fails to cause the dismissal
of such petition or appointment within sixty (60) days after Tenant is notified
of the same.

               (v)  Any Transfer or attempted Transfer of this Lease in
violation of the terms and conditions set forth in Section 6.3 above.

               (vi) Tenant's failure to vacate and yield up the Premises as
required by this Lease upon the expiration or earlier termination of the Term
hereof.

          (b)  In the event of any such Event of Default, whether or not the
Term shall have begun, in addition to any other remedies available to Landlord
at law or in equity, Landlord shall have the immediate option, or the option at
any time while such Event of Default exists, without further notice, to
terminate this Lease and all rights of Tenant hereunder by notice to Tenant; and
this Lease shall thereupon come to an end as fully and completely as if the date
such notice is given were the date herein originally fixed for the expiration of
the Term, and Tenant shall then quit and surrender the Premises to Landlord, but
Tenant shall remain liable as hereinafter provided.

     7.2  Damages.
          -------

          (a)  In the event that this Lease is terminated under any of the
provisions contained in Section 7.1 or shall be otherwise terminated for breach
of any obligation of Tenant, Tenant covenants to pay forthwith to Landlord, as
compensation, the present value of the excess of the total rent reserved for the
residue of the Term over the rental value of the Premises for said residue of
the Term.  In calculating the rent reserved there shall be included, in addition
to the Base Rent and all additional rent, the value of all other considerations
agreed to be paid or performed by Tenant for said residue.  Tenant further
covenants as an additional and cumulative obligation after any such termination
to pay punctually to Landlord all the sums and perform all the obligations which
Tenant covenants in this Lease to pay and to perform in the same manner and to
the same extent and at the same time as if this Lease had not been terminated.
In calculating the amounts to be paid by Tenant under the immediately preceding
covenant Tenant shall be credited with any amount paid to Landlord as
compensation as in this Section 7.2 provided and also with the net proceeds of
any rent obtained by Landlord by reletting the Premises, after deducting all
Landlord's reasonable expenses in connection with such reletting, including,
without limitation, all repossession costs, brokerage commissions, fees for
legal services and expenses of preparing the Premises for such reletting, it
being agreed by Tenant that Landlord may (i)  relet the Premises or any part or
parts thereof, for a term or terms which may at Landlord's option be equal to or
less than or exceed the period which would otherwise have constituted the
balance of the Term and may grant such concessions and free rent as Landlord in
its good faith judgment considers advisable or necessary to relet the same, and
(ii) make such alterations, repairs and decorations in the Premises as Landlord
in its good faith judgment considers advisable or necessary to relet the same,
and no action of Landlord in accordance with the foregoing or failure to relet
or to collect rent under reletting shall operate or be construed to release or
reduce Tenant's liability as aforesaid; provided, however, that Landlord shall
use reasonable efforts to relet the Premises and to collect rent due in
connection with such reletting.

                                     -25-
<PAGE>

          (b)  In lieu of any other damages or indemnity and in lieu of full
recovery by Landlord of all sums payable under all the foregoing provisions of
this Section 7.2, Landlord may by written notice to Tenant, at any time after
this Lease is terminated under any of the provisions contained in Section 7.1 or
is otherwise terminated for breach of any obligation of Tenant and before such
full recovery, elect to recover, and Tenant shall thereupon pay, as liquidated
damages, an amount equal to the aggregate of the Base Rent and additional rent
accrued under Sections 3.1 and  3.2 in the 12 months ended next prior to such
termination plus the amount of Base Rent and additional rent of any kind accrued
and unpaid at the time of termination and less the amount of any recovery by
Landlord under the foregoing provision of this Section 7.2 up to the time of
payment of such liquidated damages.

          (c)  Nothing contained in this Lease shall limit or prejudice the
right of Landlord to prove for and obtain in proceedings for bankruptcy or
insolvency by reason of the termination of this Lease, an amount equal to the
maximum allowed by any statute or rule of law in effect at the time when, and
governing the proceedings in which, the damages are to be provided, whether or
not the amount be greater, equal to, or less than the amount of the loss or
damages referred to above.

          (d)  Landlord's remedies under this Lease are cumulative and not
exclusive of any other remedies to which Landlord may be entitled at law or in
equity in case of Tenant's breach or threatened breach of this Lease.

                                 ARTICLE VIII
                          CASUALTY AND EMINENT DOMAIN

     8.1  Termination or Restoration; Rent Adjustment.
          -------------------------------------------

          (a)  (a) If all of the Building or the Property is taken by eminent
domain, this Lease shall terminate as of the date of such taking.  If any
portion of the Building or the Common Areas are taken by eminent domain and
Landlord, in good faith, concludes that such taking shall materially interfere
with the performance by Landlord of its obligations under this Lease, then
Landlord shall have the right to terminate this Lease by written notice to
Tenant. Tenant shall have the right to terminate this Lease by written notice to
Landlord if (i) thirty-four percent (34%) or more of the rentable area of the
Building is taken by eminent domain for a period of twelve (12) months or more,
(ii) access to the Lot is permanently taken, (iii) utility services are
permanently disrupted as a result of a taking, or (iv) if fifty (50) or more
parking spaces are permanently taken by eminent domain.  If either Landlord or
Tenant exercise such right, this Lease shall terminate as of the date of such
taking as though such date were the date of the ordinary expiration of the Term
of this Lease.

          (b)  (b) Within 45 days after any portion of the Building or the
Common Areas is damaged by fire or other casualty, Landlord shall give written
notice to Tenant of Landlord's reasonable estimate of the time required to
complete repairs of such damage.  If the Building or the Common Areas are
damaged by fire or other casualty and, in Landlord's reasonable estimate,
repairs of such damage will take more than 365 days, Landlord and Tenant shall
each of the right to terminate this Lease by written notice to the other within
30 days after Tenant receives such estimate from Landlord.  Furthermore, if a
casualty occurs during the last thirty (30) months of

                                     -26-
<PAGE>

the Term, and Landlord reasonably estimates that more than three (3) months will
be required to complete repairs of the damage resulting therefrom, Landlord may
terminate this Lease upon written notice to Tenant. If either Landlord or Tenant
give such notice of termination to the other, this Lease shall terminate 60 days
after the date of such notice of termination.

          (c)  (c) If neither Landlord nor Tenant exercise their respective
rights to terminate this Lease under Sections 8.1(a) and 8.1(b) of this Lease,
Landlord shall thereafter use due diligence to restore the Building and/or the
Common Areas as near as practicable to such condition as existed before such
fire, casualty or taking, provided that Landlord's obligation to restore the
Building and/or the Common Areas shall be limited to the amount of available
insurance proceeds and any additional funds voluntarily contributed by Tenant.
If, for any reason, such restoration shall not be substantially completed within
365 days after such fire, casualty or taking (which 365-day period may be
extended due to Force Majeure, but in no event shall such extension exceed an
additional 90 days), Tenant shall have the right to terminate this Lease by
giving written notice to Landlord, in which event this Lease shall terminate 30
days after the date of such notice unless Landlord renders the Building and the
Common Areas Ready for Occupancy before the end of such 30-day period.  Such
termination right shall be exercised by Tenant, if at all, within thirty (30)
days after the expiration of Landlord's period for substantially completing
restoration, and if Tenant fails to exercise such termination right within such
thirty (30) day period, Tenant shall be deemed to have irrevocably waived such
right.  If at any time Landlord determines that the amount of available
insurance proceeds shall be insufficient to complete such restoration, Landlord
shall give written notice of such insufficiency to Tenant, and Tenant shall have
the option either (x) to commit in writing to contribute funds sufficient to
complete such restoration, in which case Landlord shall proceed with diligence
to complete such restoration using the available insurance proceeds and such
funds contributed by Tenant and the foregoing provisions of this paragraph (c)
shall apply, or (y) to terminate this Lease by written notice of such
termination to Landlord, in which case this Lease shall terminate 30 days after
the date of such notice.  Notwithstanding anything to the contrary set forth
herein, Landlord's obligation to restore the Building and Common Areas shall be
subject to the availability of sufficient insurance proceeds and the consent of
the holder of any Mortgage upon the Property, and in the event that such consent
is withheld or the holder of any such Mortgage does not allow Landlord the use
of sufficient insurance proceeds, Landlord may give written notice to Tenant
pursuant to the immediately preceding sentence.

          (d)  (d) If the Building and/or the Common Areas shall be damaged by
fire or casualty, Base Rent and additional rent payable by Tenant shall abate
proportionately for the period in which, by reason of such damage, there is
substantial interference with Tenant's use of the Premises, having regard to the
extent to which Tenant may be required to discontinue Tenant's use of all or a
portion of the Premises, but such abatement or reduction shall end if and when
Landlord shall have substantially completed restoration of the Building and the
Common Areas.  For purposes hereof, Landlord's Work shall be deemed
substantially complete when the Building and Common Areas are Ready for
Occupancy (as that term is defined in Section 2.2) and when the Leasehold
Improvements (and Alterations, subject to the immediately following sentence)
are complete within the meaning of Section 4.2(a).  Notwithstanding anything to
the contrary set forth herein, if Landlord was not notified of the existence of
any Alterations prior to the occurrence of a casualty or condemnation, Landlord
shall not have any obligation to restore

                                     -27-
<PAGE>

such Alterations. If the Building and/or the Common Areas shall be affected by
any exercise of the power of eminent domain, Base Rent and additional rent
payable by Tenant shall be justly and equitably abated and reduced according to
the nature and extent of the loss of use thereof suffered by Tenant.

     8.2  Eminent Domain Damages.
          ----------------------

Landlord reserves to itself any and all rights to receive awards made for
damages to the Premises and Building and Lot and the leasehold hereby created,
or any one or more of them, accruing by reason of exercise of eminent domain or
by reason of anything lawfully done in pursuance of public or other authority.
Tenant hereby releases and assigns to Landlord all Tenant's rights to such
awards, and covenants to deliver such further assignments and assurances thereof
as Landlord may from time to time request.  Nothing contained herein shall be
deemed to preclude Tenant from obtaining, or to give Landlord any interest in,
any separate award to Tenant for loss or damage to Tenant's trade fixtures and
personal property or Tenant's relocation costs.

     8.3  Temporary Taking.
          ----------------

Any contrary provisions of this Article VIII notwithstanding, in the event of
any taking of the Premises or any part thereof for use for a period of not more
than twelve (12) months, (i) this Lease shall be and remain unaffected thereby
and rent shall not abate, and (ii) Tenant shall be entitled to receive for
itself such portion or portions of any award made for such use with respect to
the period of the taking which is within the Term, provided that if such taking
shall remain in force at the expiration or earlier termination of this Lease,
Tenant shall then pay to Landlord a sum equal to the reasonable cost of
performing Tenant's obligations under Section 6.1  with respect to surrender of
the Premises and upon such payment shall be excused from such obligations.

                                  ARTICLE IX
                   RIGHTS OF PARTIES HOLDING PRIOR INTERESTS

     9.1  Lease Subordinate - Superior.
          ----------------------------

This Lease shall be subordinate to any mortgage ("Mortgage") now or hereinafter
placed on the Property, and to each advance made or hereafter to be made under
any Mortgage, and to all renewals, modifications, consolidations, replacements
and extensions thereof and all substitutions therefor, provided, however, such
subordination shall be conditioned upon Tenant receiving from the holder of such
Mortgage an agreement (a "Non-Disturbance Agreement"), in recordable form, on
the part of such holder (and its successors or assigns, including any purchaser
at a foreclosure sale) to recognize this Lease and all of Tenant's rights
hereunder as though this Lease were prior to any such Mortgage and to assume,
subject to the remaining provisions of this Section, the obligations of Landlord
under this Lease in the event that such holder (or such successors or assigns)
succeeds to Landlord's title to the mortgaged premises or interest under this
Lease.  Such Non-Disturbance Agreement shall be satisfactory to such mortgagee
in form and substance, provided however, that the provisions of such Non-
Disturbance Agreement which relieve the mortgagee and its successors and assigns
from liability under this Lease shall not be materially greater than those
described in paragraphs (a) through (i)

                                     -28-
<PAGE>

below. Tenant hereby agrees that such holder or the purchaser at a foreclosure
sale or otherwise shall not be:

          (a)  liable for any act or omission of a prior Landlord (including the
mortgagor); or

          (b)  subject to any offset or defenses which the Tenant might have
against any prior Landlord (including the mortgagor); or

          (c)  bound by any rent or additional rent which the Tenant might have
paid in advance to any prior Landlord (including the mortgagor) for any period
beyond the month in which foreclosure or sale occurs; or

          (d)  bound by any Letter of Credit (as hereinafter defined) or
security deposit which Tenant may have paid to any prior Landlord, unless such
holder or purchaser has possession or control of such Letter of Credit or
security deposit; or

          (e)  bound by any amendment or modification of this Lease made without
such holder's or purchaser's consent; or

          (f)  bound by any provisions of Section 2.2 or 4.1 which require
Landlord to perform the Landlord's Work and render the Building Ready for
Occupancy; or

          (g)  personally liable under this Lease and such holder's liability
under the Lease shall be limited to the interest of such holder in the Property
and any proceeds of insurance relating to the Property; or

          (h)  liable for any fact or circumstance or condition to the extent
existing or arising prior to the mortgagee's (or such purchaser's) succession to
the interest of the Landlord under the Lease, provided that if any such
circumstance or condition continues in existence after the date on which such
mortgagee or purchaser and Tenant are in privity of estate (and if such
circumstance or condition constitutes a default by Landlord hereunder), such
mortgagee or purchaser shall, subject to the provisions of Section 9.2 hereof,
be liable as if such circumstance or condition arose on the date such privity of
estate first arose; or

          (i)  obligated to apply the proceeds of any casualty insurance or
eminent domain award to the restoration of the Property, to the extent such
obligation is inconsistent with the provisions of the Mortgage.

In the event that any mortgagee or its successor in title shall succeed to the
interest of Landlord, then, Tenant shall attorn to such mortgagee or successor
and to recognize such mortgagee or successor as its Landlord.  Any monetary
judgment obtained by Tenant under the Lease against the mortgagee or such
successor shall be satisfied solely out of the mortgagee's or such successor's
interest in the Property and any proceeds of insurance relating to the Property,
and Tenant shall not seek recovery against or out of any other assets of
mortgagee or such successor.

Notwithstanding the foregoing, any mortgagee may at its election subordinate its
Mortgage to this Lease without the consent or approval of Tenant.

                                     -29-
<PAGE>

Tenant agrees to execute and deliver promptly any appropriate certificates or
instruments requested by Landlord or any mortgagee to carry out the
subordination and attornment agreements contained in this Section 9.1.

     9.2  Rights of Mortgagee to Cure.
          ---------------------------

No act or failure to act on the part of Landlord which would entitle Tenant,
under the terms of this Lease or as a matter of law, to be released from
Tenant's obligations hereunder or to terminate this Lease shall result in a
release of such obligations or a termination of this Lease unless Tenant first
gives written notice of and a specific description of Landlord's act or failure
to act to Landlord's mortgagees of whom Tenant has been given written notice by
Landlord, if any, and such mortgagee fails to cure such default within thirty
(30) days after receipt of such notice.  However, if such cure reasonably
requires more than thirty days to effect, such mortgagee shall have such
additional time as is reasonably necessary in the circumstances, including time
to take possession of the Property.  This section shall not impose any
obligation on any such mortgagee.  Landlord shall, from time to time, notify
Tenant as to the identity of Landlord's mortgagees; provided, however, that
Tenant's execution of estoppel certificates, nondisturbance agreements or
similar agreements which identify Landlord's mortgagee shall be deemed to be
notice to Tenant hereunder.

                                  ARTICLE X
                                 MISCELLANEOUS

     10.1 Representations by Tenant.
          -------------------------

Tenant represents and warrants that those persons executing this Lease on
Tenant's behalf are duly authorized to execute and deliver this Lease on its
behalf, and that this Lease is binding upon Tenant in accordance with its terms
and upon execution of this Lease.

     10.2 Notices.
          -------

Any notice, demand or other communication required or permitted hereunder shall
be in writing and shall be addressed to Landlord at Landlord's Address, with a
copy to Hale and Dorr LLP, 60 State Street, Boston, Massachusetts 02109, Attn:
William R. O'Reilly, Jr., Esq.; and to Tenant at Tenant's Address with a copy to
Testa, Hurwitz & Thibeault, LLP, 125 High Street, Boston, Massachusetts 02110,
Attn:  Real Estate Department.  Any notice, demand or other communication so
addressed shall be deemed duly given when delivered by hand (or when delivery is
refused), one day after being sent by Federal Express (or other guaranteed
overnight delivery service) or three days after being sent by registered or
certified mail, return receipt requested.  Either party may change its address
by giving notice to the other.

     10.3 No Waiver or Oral Modification.
          ------------------------------

No provision of this Lease shall be deemed waived by Landlord or Tenant except
by a signed written waiver.  No consent to any act or waiver of any breach or
default, express or implied, by Landlord or Tenant, shall be construed as a
consent to any other act or waiver of any other breach or default.  Landlord's
failure to enforce any covenant or condition of this Lease shall not

                                     -30-
<PAGE>

be deemed a waiver thereof. The receipt by Landlord of any rent with knowledge
of the breach of any covenant of this Lease shall not be deemed a waiver of such
breach, and the acceptance of any rental payment in any amount less than the
full sum due shall not constitute a waiver of any claim to the remaining
balance. This Lease may not be changed or amended orally, but only by a written
instrument.

     10.4 Partial Invalidity.
          ------------------

If any provision of this Lease, or the application thereof in any circumstances,
shall to any extent be invalid or unenforceable, the remainder of this Lease
shall not be affected thereby, and each provision hereof shall be valid and
enforceable to the fullest extent permitted by law.

     10.5 Certain Landlord Remedies.
          -------------------------

If Tenant fails to perform any obligation under this Lease (regardless of
whether such failure has matured into an Event of Default), Landlord may give
written notice to Tenant that it seeks to perform such obligation on Tenant's
behalf (provided that in the case of emergency, no such notice shall be
required), and if Tenant does not commence performance of such obligation within
ten (10) days after Landlord's notice, and thereafter diligently pursue such
performance to completion, then Landlord may enter the Premises and perform such
obligation on Tenant's behalf. In so doing, Landlord may make any payment of
money or perform any other act.  All sums so paid by Landlord, and all
incidental costs and expenses, shall be considered additional rent under this
Lease and shall be payable to Landlord within 30 days after Tenant receives
Landlord's written demand, together with interest from the date of demand to the
date of payment at the Interest Rate.  For purposes of this Lease, the "Interest
Rate" shall mean the lesser of the maximum interest rate permitted by law or two
(2) percentage points above the then prevailing prime rate as set by BankBoston,
N.A. in its main office in Boston, MA  (or, if such bank ceases to exist, the
then largest bank in the Commonwealth of Massachusetts).

     10.6 Tenant's Estoppel Certificate.
          -----------------------------

Within twenty (20) days after written request by Landlord, Tenant shall execute,
acknowledge and deliver to Landlord a written statement certifying, to the
extent true, (a) that this Lease is unmodified and in full force and effect, or
is in full force and effect as modified and stating the modifications; (b) the
amount of Base Rent and the date to which Base Rent and additional rent have
been paid in advance; (c) the amount of any security deposited with Landlord;
and (d) that, to the best of Tenant's actual knowledge, Landlord is not in
default hereunder or, if Landlord is claimed to be in default, stating the
nature of any claimed default, and (e) such other factual matters as may be
reasonably requested by Landlord which are not ascertainable from the terms of
this Lease.  Any such statement may be relied upon by a purchaser, assignee or
lender. Tenant's failure to execute and deliver such statement within the time
required shall be a default under this Lease and shall also be conclusive upon
Tenant that (1) this Lease is in full force and effect and has not been modified
except as represented by Landlord; (2) there are no uncured defaults in
Landlord's performance and Tenant has no right of offset, counterclaim or
deduction against rent; and (3) not more than one month's Base Rent has been
paid in advance.  In connection with any Transfer of this Lease or major
corporate financing by Tenant, Landlord shall, within twenty (20) days after
written request by Tenant, acknowledge and deliver to

                                     -31-
<PAGE>

Tenant a written statement containing substantially similar certifications
regarding Tenant to those listed above regarding Landlord.

     10.7  Waiver of Subrogation.
           ---------------------

Any other provision of this Lease notwithstanding, Landlord and Tenant each
hereby waive all rights of recovery against the other and against the officers,
employees, agents, and representatives of the other, on account of damage to the
property arising from any loss for which insurance is carried or required to be
carried pursuant to this Lease. Each party shall notify its insurers that the
foregoing waiver is contained in this Lease.  Landlord and Tenant shall cause
each insurance policy covering its property obtained by each of them to provide
that the insurer waives all right of recovery by way of subrogation against
either Landlord or Tenant in connection with any loss or damage covered by such
policy.

     10.8  All Agreements; No Representations.
           ----------------------------------

This Lease contains all of the agreements of the parties with respect to the
subject matter hereof and supersedes all prior dealings between them with
respect to such subject matter.  Each party acknowledges that the other has made
no representations or warranties of any kind except as may be specifically set
forth in this Lease.

     10.9  Brokerage.
           ---------

Each party represents and warrants that, other than the Brokers, it has not
dealt with any real estate broker or agent in connection with this Lease or its
negotiation.  Each party shall indemnify the other and hold it harmless from any
cost, expense, or liability (including costs of suit and reasonable attorneys'
fees) for any compensation, commission or fees claimed by any other real estate
broker or agent in connection with this Lease or its negotiation by reason of
any act or statement of the indemnifying party.  Landlord will be responsible
for paying a commission to the Brokers in connection with this Lease.

     10.10 Successors and Assigns.
           ----------------------

This Lease shall be binding upon and inure to the benefit of the parties hereto
and their respective successors and assigns; provided, however, that the
original Landlord named herein and each successive owner of the Premises shall
be not be liable for obligations accruing after the period of their respective
ownership; provided further, that Tenant's right to make a Transfer shall always
be governed by Section 6.3 hereof.

     10.11 Construction of Document.
           ------------------------

This Lease shall be construed, governed and enforced according to the laws of
the Commonwealth of Massachusetts.  In construing this Lease, section headings
shall be disregarded.  Any recitals herein or riders or exhibits attached hereto
are hereby incorporated into this Lease by this reference.  Time is of the
essence of this Lease and every provision contained herein.  The parties
acknowledge that this Lease was freely negotiated by both parties, each of whom
was represented by counsel; accordingly, this Lease shall be construed according
to the fair meaning of its terms, and not against either party.

                                     -32-
<PAGE>

     10.12 Disputes Provisions.
           -------------------

           (a)  If either Landlord or Tenant institutes any action to enforce
the provisions of this Lease or to seek a declaration of rights hereunder, the
prevailing party shall be entitled to recover its reasonable attorneys' fees and
court costs as part of any award.

           (b)  Landlord and Tenant hereby waive trial by jury in any action,
proceeding or counterclaim brought by either of the parties hereto against the
other, on or in respect to any matter whatsoever arising out of or in any way
connected with this Lease, the relationship of Landlord and Tenant hereunder,
Tenant's use or occupancy of the Premises, and/or claim of injury or damage.

     10.13 Surrender.
           ---------

The voluntary or other surrender of this Lease by Tenant, or a mutual
cancellation thereof, shall not work a merger, and shall, at the option of
Landlord, operate as an assignment to it of any or all subleases or
subtenancies.

     10.14 Holdover.
           --------

If Tenant holds over in occupancy of the Premises after the expiration of the
Term, Tenant shall become a tenant at sufferance only, at a daily rental rate
equal to one hundred fifty (150%) percent of the daily rate of Rent in effect at
the end of the Term, and otherwise subject to the terms and conditions herein
specified, so far as applicable, and shall be liable for all damages sustained
by Landlord on account of such holding over.  This Section shall not operate as
a waiver of any right of reentry provided in this Lease, and Landlord's
acceptance of rent after expiration of the Term or earlier termination of this
Lease shall not constitute consent to a holdover or result in a renewal.  If
Tenant fails to surrender the Premises upon the expiration of the Term or
earlier termination despite demand by Landlord to do so, Tenant shall indemnify
and hold Landlord harmless from all loss or liability, including, without
limitation, any claim made by any succeeding tenant, resulting from such
failure.

     10.15 Late Payment.
           ------------

Tenant acknowledges that the late payment by Tenant to Landlord of any sums due
under this Lease will cause Landlord to incur costs not contemplated by this
Lease, the exact amount of such costs being extremely difficult and impractical
to ascertain.  Therefore, if any Base Rent or other sum due hereunder is not
paid within five (5) business days after notice from Landlord, Tenant shall pay
to Landlord, as additional rent, the sum of three percent (3%) of the overdue
amount as a late charge.  The overdue amount, if not received within ten days
thereafter, shall also bear interest, as additional rent, at the Interest Rate,
calculated from the date the late charge becomes due until the date of payment
to Landlord.  Landlord's acceptance of any late charge or interest shall not
constitute a waiver of Tenant's default with respect to the overdue amount.

     10.16 Force Majeure.
           -------------

If Landlord or Tenant is prevented from or delayed in performing any act
required of it hereunder, and such prevention or delay is caused by strikes,
labor disputes, inability to obtain

                                     -33-
<PAGE>

labor, materials, or equipment, inclement weather, acts of God, governmental
restrictions, regulations, or controls, judicial orders, enemy or hostile
government actions, civil commotion, fire or other casualty, or other causes
beyond such party's reasonable control (collectively, "Force Majeure"), the
performance of such act shall be excused for a period equal to the period of
prevention or delay. A party's financial inability to perform its obligations
shall in no event constitute Force Majeure. Nothing in this section shall excuse
or delay Tenant's obligation to pay any rent or other charges due under this
Lease.

     10.17 Limitation On Liability.
           -----------------------

In consideration of the benefits accruing hereunder, Tenant hereby covenants and
agrees that, in the event of any actual or alleged failure, breach or default
hereunder by Landlord:

          (a)  Tenant shall not seek recourse against the assets of any members,
trustees, partners, directors, beneficiaries, officers or shareholders of
Landlord, or any direct or indirect constituent member, trustee, partner,
director, officer or shareholder of Landlord's members for satisfaction of any
liability with respect to this Lease, except to the extent any such member,
trustee, partner, director, officer or shareholder has personally received any
proceeds of insurance covering the Building or the Property to which Tenant is
entitled.

          (b)  If Tenant obtains a judgment for monetary damages arising out of
a default by Landlord in the performance of its obligations under this Lease,
Tenant shall not enforce such judgment against any assets of Landlord other than
its interest in the Building and the Property and any proceeds of insurance
covering the Building or the Property.

          (c)  Except as expressly permitted under Section 10.17(a) above,
neither Landlord's members nor any direct or indirect constituent member,
trustee, partner, director, officer or shareholder of Landlord or Landlord's
members shall be sued, named as a party in any suit or action, or served with
process therein (except if necessary to properly initiate suit against
Landlord), and neither Landlord's members nor any constituent member, trustee,
partner, director, officer or shareholder of Landlord or Landlord's members
shall be required to respond to any service of process (except to the extent
necessary for Tenant to prosecute properly a suit against Landlord).

          (d)  Except as expressly permitted under Section 10.17(a) above, no
judgment will be taken against Landlord's members nor any constituent partner or
member of Landlord or Landlord's members, and no writ of execution will be
levied against the assets of Landlord's members or any such constituent partner
or member.

          (e)  These covenants and agreements are enforceable both by Landlord
and also by Landlord's beneficiary, any constituent partner of Landlord's
beneficiary, and shall bind Tenant and its successors and assigns.

     10.18 Submission Not An Option.
           ------------------------

The submission of this Lease or a summary of some or all of its provisions for
examination by Tenant does not constitute a reservation of the Premises for
Tenant or an offer to lease the

                                     -34-
<PAGE>

Premises to Tenant or the grant of an option for the Premises to Tenant,
notwithstanding any contrary provision of statutory or common law.

     10.19 Security Deposit.
           ----------------

Landlord acknowledges receipt from Tenant of an unconditional, irrevocable and
transferable letter of credit, naming Landlord and its successors and assigns as
beneficiary, drawn upon Fleet National Bank NA, or another bank or financial
institution reasonably acceptable to Landlord, in the amount of Five Hundred
Thousand Dollars ($500,000.00) (the "Letter of Credit"), which shall be held by
Landlord or its agent, as security, for the full and faithful performance of
Tenant's obligation herewith for and during the Term.  Upon the occurrence of
any Event of Default, Tenant agrees that Landlord may from time to time, without
prejudice to any other remedy, draw upon the principal amount of the Letter of
Credit (or any cash security deposit held by Landlord in lieu of the Letter of
Credit) to the extent necessary to reimburse Landlord for any Base Rent,
additional rent or other sums payable by Tenant to Landlord under this Lease by
virtue of such Event of Default.  Tenant shall not have the right to call upon
Landlord to draw upon the Letter of Credit to cure any default or fulfill any
obligation of Tenant, but such use shall be solely in the discretion of
Landlord.  Upon any conveyance of the Property by Landlord to Landlord's grantee
or transferee of the Property, the Letter of Credit thereon may be assigned or
otherwise transferred by Landlord to such grantee or transferee, and Tenant
shall cooperate to the extent necessary to effect such assignment or transfer.
Upon any such assignment or transfer, Tenant hereby releases Landlord herein
named of any and all liability with respect to the Letter of Credit, its
application and return, and Tenant agrees to look solely to such grantee or
transferee.  It is further understood that this provision shall also apply to
subsequent grantees and transferees.  Subject to Section 6.3(g) above, but
otherwise notwithstanding any other provision to the contrary set forth herein,
(i) on each anniversary of the Commencement Date, the principal amount of the
Letter of Credit (or any such cash security deposit) shall be reduced by Fifty
Thousand Dollars ($50,000.00), and (ii) the Letter of Credit (or any such cash
security deposit) shall be returned to Tenant upon the fifth (5th) anniversary
of the Commencement Date, provided however that no reduction of the principal
amount of the Letter of Credit (and such security deposit) shall occur on any
such anniversary, and the Letter of Credit (and such security deposit) shall not
be returned to Tenant upon the fifth (5th) anniversary of the Commencement Date
if (x) an Event of Default which Landlord has not waived exists on such
anniversary, or (y) Tenant is unable to provide Landlord with reasonably
satisfactory evidence that, at the time of any scheduled reduction or return,
Tenant's reported book net worth exceeds One Hundred Million Dollars
($100,000,000.00).  Any such reduction in the principal amount of the Letter of
Credit shall be accomplished as follows: (x) Tenant will provide a substitute
letter of credit to Landlord in the form of the Letter of Credit then held by
Landlord or such other form (providing to Landlord the same rights and remedies
as are set forth in the Letter of Credit then held by Landlord) as may be
reasonably acceptable to Landlord, except that the principal amount of the
substitute letter of credit shall be the reduced principal amount required
hereunder; and (y) if Tenant is entitled to a reduction in the principal amount
of the Letter of Credit, then Landlord shall return the Letter of Credit
originally held by Landlord to Tenant and thereafter hold the substitute letter
of credit as the "Letter of Credit" hereunder.  In the event that (a) Tenant is
not entitled to a reduction in the principal amount of the Letter of Credit, but
the Letter of Credit is written such that the principal amount will nevertheless
automatically be reduced, or (b) the

                                     -35-
<PAGE>

Letter of Credit is written such that it will expire prior to the date on which
Tenant is entitled to its return, and the Letter of Credit is not renewed or
replaced at least thirty (30) days prior to such expiration date, then Landlord
shall have the right to draw upon the Letter of Credit so that Landlord will, at
all times during the Term of this Lease hold, in the form of cash or in the form
of the Letter of Credit or both, a sum equal to the principal amount of the
Letter of Credit required hereunder from time to time.  At any time during the
term of this Lease, Tenant shall have the right to convert the Letter of Credit
into a cash security deposit by tendering to Landlord a sum equal to the
principal amount of the Letter of Credit required to be maintained by Tenant at
that time.  If Tenant tenders such sum, in immediately available funds, or a
replacement of the Letter of Credit for any proper purpose under this Section
10.19 (including without limitation to extend the date of the expiration of the
Letter of Credit or to effect a reduction in the principal amount of the Letter
of Credit), Landlord shall promptly cooperate with Tenant to exchange such sum
or such replacement, as the case may be, for the Letter of Credit in Landlord's
possession.  Landlord shall deposit any such sum tendered by Tenant in an
interest-bearing money-market account (which need not be separate or segregated
from Landlord's other funds) and, provided no Event of Default exists and is
continuing, shall  pay all interest accruing on such sum to Tenant at least once
annually.  All such sums held in the form of cash shall be held as a security
deposit otherwise subject to the terms hereof, for the full and faithful
performance of Tenant's obligation herewith.  Landlord shall return the Letter
of Credit (or such security deposit) to Tenant within 30 days after the
expiration of the Term, after drawing upon such Letter of Credit or security
deposit to the extent necessary to cure any Event of Default existing under this
Lease at that time.

     10.20 Evidence of Authority.
           ---------------------

Simultaneously with the execution of this Lease, Tenant shall deliver to
Landlord a certificate of the Secretary or an Assistant Secretary of Tenant
evidencing the incumbency of the officer(s) of Tenant executing this Lease on
behalf of Tenant and the resolutions of Tenant's board of directors authorizing
such execution.

     10.21 Notice of Lease.
           ---------------

Tenant agrees not to record this Lease, but Landlord and Tenant shall each
execute and deliver a notice of this Lease in form appropriate for recording or
registration, and, if this Lease is terminated before the Term expires, an
instrument in such form acknowledging the date of termination.

     10.22 Rules and Regulations.
           ---------------------

Landlord may enact reasonable rules and regulations ("Rules and Regulations")
governing the use of the Common Areas, which Rules and Regulations shall be
generally applicable to all occupants of the Property and uniformly enforced by
Landlord and shall not be inconsistent with the terms of this Lease or otherwise
materially interfere with Tenant's use and enjoyment of the Premises and the
Common Areas.

                                     -36-
<PAGE>

                                  ARTICLE XI
             DETERMINATION OF FAIR MARKET RENT AND TENANT OPTIONS

     11.1  Fair Market Rent.
           ----------------

Whenever any provision of this Lease provides that the Fair Market Rent shall be
calculated, "Fair Market Rent" shall mean that the fair market rent of the
Premises as if the Premises were unencumbered by this Lease, but taking into
account all relevant factors, including without limitation, the terms of this
Lease and rents for comparable space in the vicinity of Chelmsford,
Massachusetts, as of the commencement of the period in question under market
conditions then existing. Fair Market Rent shall be determined by agreement
between Landlord and Tenant, but if Landlord and Tenant are unable to agree upon
the Fair Market Rent at least six months prior to the date upon which the Fair
Market Rent is to take effect, then the Fair Market Rent shall be determined by
appraisal made as hereinafter provided by a board of three (3) reputable
independent commercial real estate consultants, appraisers, or brokers, each of
whom shall have at least ten years of experience in the suburban Boston office
rental market. Tenant and Landlord shall each appoint one such appraiser and the
two appraisers so appointed shall appoint the third appraiser, provided however
that the third such appraiser shall be either a Senior Real Property Appraiser
of the Society of Real Estate Appraisers or a member of the Appraisal Institute
(or any successor organization). The cost and expenses of each appraiser
appointed separately by Tenant and Landlord shall be borne by the party who
appointed the appraiser. The cost and expenses of the third appraiser shall be
shared equally by Tenant and Landlord. Landlord and Tenant shall appoint their
respective appraisers at least five months prior to commencement of the period
for which Fair Market Rent is to be determined and shall designate the
appraisers so appointed by notice to the other party. The two appraisers so
appointed and designated shall appoint the third appraiser at least four months
prior to the commencement of such period and shall designate such appraiser by
notice to Landlord and Tenant. The board of three appraisers shall determine the
Fair Market Rent of the space in question as of the commencement of the period
to which the Fair Market Rent shall apply and shall notify Landlord and Tenant
of their determinations at least sixty days prior to the commencement of such
period. If the determinations of the Fair Market Rent of any two or all three of
the appraisers shall be identical in amount, said amount shall be deemed to be
the Fair Market Rent of the subject space. If the determinations of all three
appraisers shall be different in amount, the average of the two values nearest
in amount shall be deemed the Fair Market Rent. The Fair Market Rent of the
subject space determined in accordance with the provisions of this Section shall
be binding and conclusive on Tenant and Landlord.

Notwithstanding the foregoing, if either party shall fail to appoint its
appraiser within the period specified above (such party referred to hereinafter
as the "failing party"), the other party may serve notice on the failing party
requiring the failing party to appoint its appraiser within ten (10) days of the
giving of such notice and if the failing party shall not respond by appointment
of its appraiser within said ten (10) day period, then the appraiser appointed
by the other party shall be the sole appraiser whose determination of the Fair
Market Rent shall be binding and conclusive upon Tenant and Landlord.

                                     -37-
<PAGE>

     11.2  Option to Extend.
           ----------------

Tenant shall have the right and option to extend the Term for an additional
period (the "Extension Term") commencing the day after the expiration of the
original Term referred to in Section 1.2 (the "Original Term") and ending five
(5) years thereafter, provided that in the case of such option Tenant shall give
Landlord notice of Tenant's exercise of such option at least twelve (12) months
prior to the expiration of the Original Term and provided further that in the
case of such option no Event of Default shall have occurred and be continuing.
Prior to the exercise by Tenant of such option, the expression "Term" shall mean
the Original Term, and after the exercise by Tenant of such option, the
expression "Term" shall mean the Original Term as it has been then extended by
the Extension Term.  Except as expressly otherwise provided in the following
paragraphs, all the terms, covenants, conditions, provisions and agreements in
the Lease contained shall be applicable to the additional period to which the
Original Term shall be extended as aforesaid.  If Tenant shall give notice of
its exercise of said option to extend in the manner and within the time period
provided aforesaid, the Term shall be extended upon the giving of such notice
without the requirement of any further action on the part of either Landlord or
Tenant.  If Tenant shall fail to give timely notice of the exercise of any such
option as aforesaid, Tenant shall have no right to extend the Term of this
Lease, time being of the essence of the foregoing provisions.

The Base Rent payable during the Extension Term shall be the greater of (i) the
Base Rent in effect for last twelve months of the Original Term or (ii) the Fair
Market Rent for the Premises as of the commencement of the Extension Term.  The
Fair Market Rent shall be determined in accordance with the provisions of
Section 11.1 above.

                       SIGNATURE PAGE ON FOLLOWING PAGE

                                     -38-
<PAGE>

   EXECUTED as a sealed instrument in two or more counterparts on the Date of
Lease.

                                  Landlord:

                                  Farley White Associates, LLC

                                  By: /s/ Roger W. Altreuter
                                     -----------------------------------
                                     Name: Roger W. Altreuter
                                     Title: Manager

                                  Tenant:

                                  Sycamore Networks, Inc.

                                  By: /s/ Frances M. Jewels
                                     -----------------------------------
                                     Name: Frances M. Jewels
                                     Title: Vice President

                                  By: /s/ Frances M. Jewels
                                     -----------------------------------
                                     Name: Frances M. Jewels
                                     Title: Treasurer

                                     -39-
<PAGE>

                                   EXHIBIT A

                         LEGAL DESCRIPTION OF THE LOT

A certain parcel of land in Chelmsford, Middlesex County, Massachusetts as shown
as Lot B on a subdivision plan entitled "Plan of Land in Chelmsford,
Massachusetts Assessor's Plat 113, Lot 13" prepared by Vanasse Hangen Brustlin,
Inc., dated April 16, 1998 recorded with Middlesex North District Registry of
Deeds as Instrument No. 33514 in Plan Book 197, Page 26.  Said Lot B contains
191,173 + square feet.
<PAGE>

                                   EXHIBIT B

                         BASE BUILDING SPECIFICATIONS

150 APOLLO DRIVE DRAWING LIST

ARCHITECTURAL:

A0.1   Legends, Room Finish Schedule, Partition Types,
       Misc. Details, Door Schedules, Door & Frame Types

A2.1   First Floor Plan

A2.2   Second Floor Plan

A2.3   Third Floor Plan

A2.4   Roof Plan

A3.1   Exterior Elevations

A3.2   Exterior Elevations

A5.1   Wall Sections

A5.2   Wall Sections

A6.1   Wall Section Details

A6.2   Wall Section Details

A6.3   Wall Section Details

A6.4   Roof Details

A7.1   Enlarged Plan Details

A8.1   Enlarged Stair Plans/Sections & Details

A9.1   Enlarged Elevator Plan Elevator Sections & Details

A10.1  Enlarged Toilet Cores - Elevations & Details Fixture Schedule
<PAGE>

A10.2 Toilet Cores and Finish Plans Finish Elevations

A11.1 Lobby Stair Sections & Details

A11.2 Lobby Finish Plans

A11.3 Interior Elevations

A11.4 Interior Elevations /Sections & Details

A12.1 First Floor reflected Ceiling Plan

A12.2 Second Floor reflected Ceiling Plan

A12.3 Third Floor reflected Ceiling Plan

STRUCTURAL:

FIRE PROTECTION:

FP-1  Fire Protection Legends and Diagrams

FP-2  Fire Protection First Floor Plan

FP-3  Fire Protection Second Floor Plan

FP-4  Fire Protection Third Floor Plan

PLUMBING:

P-1   Plumbing Legends, Diagrams & Schedules

P-2   Plumbing Buried Piping Plan

P-3   Plumbing First Floor Plan

P-4   Plumbing Second Floor Plan

P-5   Plumbing Third Floor Plan

P-6   Plumbing Roof Plan
<PAGE>

HVAC

H-1 HVAC Legends, Schedules & General Notes

H-2 HVAC Details

H-3 HVAC Sections

H-4 HVAC First Floor Plan - New Ductwork

H-5 HVAC Second Floor Plan - New Ductwork

H-6 HVAC Third Floor Plan - New Ductwork

H-7 HVAC Roof Floor Plan - New Ductwork<PAGE>

Exhibit 10.1

                          PURCHASE AND SALE AGREEMENT

                                  DATED AS OF

                                April 28, 2000

                                    BETWEEN

                                N'TANDEM TRUST

                                      AND

                          WINDSOR PARK PROPERTIES 6,
                       A California Limited Partnership

                                       5
<PAGE>

                          PURCHASE AND SALE AGREEMENT

PURCHASE AND SALE AGREEMENT, dated April 28, 2000, between N'Tandem Properties,
L.P., a Delaware limited Partnership (the "Buyer"), N'Tandem Trust, an
unincorporated California business trust and the sole general partner of the
Partnership ("N'Tandem"), and Windsor Park Properties 6, A California Limited
Partnership (the "Seller"), relating to the purchase by the Buyer from the
Seller of certain real property and ownership interests in real property, as
more particularly described herein. The Buyer and the Seller hereby agree as
follows:

                                   ARTICLE I

                 PURCHASE OF PROPERTY AND OWNERSHIP INTERESTS

     1.1  Purchase of Property and Ownership Interests. At the Closing described
          --------------------------------------------
          in Paragraph 2.1, the Buyer will purchase the real property owned in
          fee simple (the "Property") and the ownership interests in real
          properties (the "Ownership Interests") described in Exhibit A hereto,
                                                              ---------
          and the Seller shall transfer the Property and the Ownership Interests
          to the Buyer free and clear of all liens (the "Sales").

     1.2  Purchase Price. The aggregate purchase price for the Property and the
          Ownership Interests is $15,438,100, which represents the aggregate
          appraised value for the Property and the Ownership Interests less the
          aggregate discount applicable to the Ownership Interests, and is
          subject to the adjustments set forth in this Paragraph 1.2 (as so
          adjusted, the "Purchase Price"). To the extent that the Property, or
          any real property underlying any Ownership Interest (each, an
          "Underlying Property"), fails to be free and clear of all mortgage
          indebtedness and/or other liens, the Buyer shall receive at the
          Closing a credit against the Purchase Price (i) in the case of
          mortgage indebtedness and/or other liens encumbering the Property as
          of the closing date, in an amount equal to such mortgage indebtedness
          and/or other liens (or in the case of mortgage indebtedness and/or
          other liens relating to the Property encumbering more than one real
          property, in an amount equal to the product of the amount of such
          mortgage indebtedness and/or other liens times the ratio that the
          appraised value of the Property bears to the aggregate appraised
          values of all real properties encumbered by such mortgage indebtedness
          and/or other liens), and (ii) in the case of mortgage indebtedness
          and/or other liens encumbering any Underlying Property as of the
          closing date, in an amount equal to such mortgage indebtedness and/or
          other liens (or in the case of mortgage indebtedness and/or other
          liens relating to an Underlying Property

                                       6
<PAGE>

          encumbering more than one real property, in an amount equal to the
          product of the amount of such mortgage indebtedness and/or other liens
          times the ratio that the appraised value of such Underlying Property
          bears to the aggregate appraised values of all real properties
          encumbered by such mortgage indebtedness and/or other liens) times the
          percentage ownership of such Underlying Property allocable or
          attributable to the Ownership Interest.

                                  ARTICLE II

                                  THE CLOSING

     2.1  Time and Place of Closing. The closing (the "Closing") of the purchase
          -------------------------
          of the Property and the Ownership Interests will take place at the
          offices of LandAmerica National Commercial Services, 3636 North
          Central Avenue, Suite 350, Phoenix, Arizona, at 2:00 P.M. Phoenix
          time, on May 31, 2000 or such other date as may be agreed to by the
          Buyer and the Seller (the "Closing Date").

     2.2  Seller's Actions at Closing. At the Closing, the Seller shall deliver
          ---------------------------
          to the Buyer (i) deeds of conveyance in proper form for recording
          relating to the Property and the Town and Country Estates, Carefree
          Village and Garden Walk Ownership Interests, (ii) an Assignment
          Agreement, in form and substance satisfactory to the Buyer, assigning
          to the Buyer all of the Seller's right, title and interest in and to
          the Rancho Margate and Winter Haven Ownership Interests, and (iii)
          such other documents and instruments, and take such other action, as
          may be necessary or desirable to effect the transfer of the Properties
          and the Ownership Interests to the Buyer, in accordance with this
          Agreement.

     2.3  Buyer's Actions at Closing. At the Closing, the Buyer will deliver to
          --------------------------
          the Seller a certified or bank cashier's check, or evidence of a wire
          transfer of immediately available funds to an account specified by the
          Seller at least 24 hours before the Closing, in an amount equal to the
          Purchase Price.

     2.4  Closing Costs. With respect to the Property and the Town and Country
          -------------
          Estates, Carefree Village and Garden Walk Ownership Interests, the
          Seller shall pay at the Closing such closing costs as are customarily
          paid by sellers of real property in Colorado. The Buyer shall be
          responsible for all other closing costs relating to the transfer of
          the Property and the Ownership Interests payable at the Closing.

                                       7
<PAGE>

                                  ARTICLE III

                        REPRESENTATIONS AND WARRANTIES

     3.1  Buyer's Representations and Warranties. The Buyer represents and
          --------------------------------------
          warrants to the Seller as follows:

          (a)  The Buyer is a limited partnership duly formed and validly
               existing under the laws of the State of Delaware.

          (b)  The Buyer has all trust power and authority necessary to enable
               it to enter into this Agreement and carry out the transactions
               contemplated by this Agreement. All partnership actions necessary
               to authorize the Buyer to enter into this Agreement and carry out
               the transactions contemplated by it have been taken. This
               Agreement has been duly executed by the Buyer and is a valid and
               binding agreement of the Buyer, enforceable against the Buyer in
               accordance with its terms.

                                  ARTICLE IV

                         ACTIONS PRIOR TO THE CLOSING

     4.1  Activities Until Closing Date. From the date of this Agreement to the
          -----------------------------
          Closing Date, the Seller will, except with the written consent of
          N'Tandem or the Buyer, operate its businesses in the ordinary course
          and in a manner consistent with the manner in which they are being
          operated at the date of this Agreement.

     4.2  Seller's Efforts to Fulfill Conditions. The Seller will use its best
          --------------------------------------
          efforts to cause all the conditions set forth in Paragraph 5.1 to be
          fulfilled prior to or at the Closing.

     4.3  Buyer's Efforts to Fulfill Conditions. The Buyer will use its best
          -------------------------------------
          efforts to cause all the conditions contained in Paragraph 5.1 to be
          fulfilled prior to or at the Closing.

                                   ARTICLE V

                        CONDITIONS PRECEDENT TO CLOSING

     5.1  Conditions to Buyer's Obligations. The obligations of the Buyer at the
          ---------------------------------
          Closing are subject to the approval of the Sales by the holders of not
          less than a majority of the issued and outstanding units of limited
          partner interest of the Seller.

                                       8
<PAGE>

                                  ARTICLE VI

                                  TERMINATION

     6.1  Right to Terminate. This Agreement may be terminated at any time prior
          ------------------
          to the Closing:

          (a)  By mutual consent of N'Tandem, the Buyer and the Seller;

          (b)  By either the Buyer or the Seller if, without fault of the
               terminating party, the Closing does not occur on or before August
               31, 2000; or

          (c)  By the Buyer or the Seller if the condition in Paragraph 5.1 is
               not satisfied on or before the Closing Date.

     6.2  Effect of Termination. If this Agreement is terminated pursuant to
          ---------------------
          Paragraph 6.1, after this Agreement is terminated, no party hereto
          will have any further rights or obligations under this Agreement.
          Nothing contained in this Paragraph will, however, relieve any party
          of liability for any breach of this Agreement which occurs before this
          Agreement is terminated.

                                  ARTICLE VII

                                    GENERAL

     7.1  Expenses. Except as otherwise provided herein, the Buyer and the
          --------
          Seller will each pay its own expenses in connection with the
          transactions which are the subject of this Agreement, including legal
          fees.

     7.2  Entire Agreement. This Agreement and the documents to be delivered in
          ----------------
          accordance with this Agreement contain the entire agreement between
          the Buyer and the Seller relating to the transactions which are the
          subject of this Agreement. There are no representations, warranties,
          understandings or

                                       9
<PAGE>

          agreements concerning the transactions which are the subject of this
          Agreement other than those expressly set forth herein and therein.

     7.3  Captions. The captions of the articles and paragraphs of this
          --------
          Agreement are for reference only and do not affect the meaning or
          interpretation of this Agreement.

     7.4  Assignments. Neither this Agreement nor any right of any party under
          -----------
          it may be assigned.

     7.5  Notices and Other Communications. Any notice or other communication
          --------------------------------
          under this Agreement must be in writing and will be deemed given when
          delivered in person or sent by facsimile (with proof of receipt at the
          number to which it is required to be sent), or on the third business
          day after the day on which mailed by first class mail from within the
          United States of America, to the following addresses (or such other
          address as may be specified after the date of this Agreement by the
          party to which the notice or communication is sent):

     If to the Seller:

          Windsor Park Properties 6, A California
            Limited Partnership
          6160 South Syracuse Way
          Greenwood Village, Colorado 80111

     If to the Buyer:

          N'Tandem Trust
          N'Tandem Properties, L.P.
          6160 South Syracuse Way
          Greenwood Village, Colorado 80111

          with a copy to:

          Clifford Chance Rogers & Wells LLP
          200 Park Avenue
          New York, New York 10166
          Facsimile:  (212) 878-8375
          Attention: Jay L. Bernstein, Esq.

     7.6  Governing Law. This Agreement will be governed by, and construed
          -------------
          under, the substantive laws of the State of Colorado.

                                      10

<PAGE>

     7.7  Amendments. This Agreement may be amended only by a document in
          ----------
          writing signed by both the Buyer and the Seller.

     7.8  Counterparts. This Agreement may be executed in two or more
          ------------
          counterparts, some of which may be signed by fewer than all the
          parties or may contain facsimile copies of pages signed by some of the
          parties. Each of those counterparts may contain the signatures of
          fewer than all the parties or may contain facsimile copies of pages
          signed by some of the parties. Each of those counterparts will be
          deemed to be an original, but all of them together will constitute one
          and the same agreement.

     IN WITNESS WHEREOF, the Buyer and the Seller have executed this Agreement,
intending to be legally bound by it, on the day shown on the first page of this
Agreement.

SELLER:

WINDSOR PARK PROPERTIES 6,
A California Limited Partnership

By:  The Windsor Corporation,
     its General Partner

     By:  /s/Steven G Waite
          -----------------
          Steven G. Waite
          President

BUYER:

N'TANDEM PROPERTIES, L.P.

By:  N'Tandem Trust,
     its general partner

     By:  /s/Gary P. McDaniel
          -------------------
          Gary P. McDaniel
          Trustee

                                      11
<PAGE>

                                   EXHIBIT A

<TABLE>
<CAPTION>
                                                                                             Debt Attributable
                                                                                                to Property           Net Purchase
                                                                                                    or                  Price of
                                     Nature        Gross Purchase Price of   Discount on     Ownership Interest         Property
                                      of            Property or Ownership     Ownership           as of               or Ownership
                    Ownership      Ownership       -----------------------   -----------     ------------------     ----------------
Name of Property   Percentage      Interest              Interest             Interest           4/28/00                Interest
----------------   ---------- ------------------         --------             --------           -------                --------
<S>                <C>        <C>                  <C>                         <C>            <C>                   <C>
Chisolm Creek         100%        Fee Simple             $ 2,940,000               __               __                 $2,940,000
 Wichita, KS
Town & Country         58%    Tenant in Common/          $ 3,132,000         $  156,600         $  899,000             $2,076,400
Estates                         Joint Venture
 Tucson, AZ                        Interest

Carefree Village       44%    Tenant in Common/          $ 2,917,200         $  291,700         $1,531,200             $1,094,300
 Tampa, FL                      Joint Venture
                                   Interest

Rancho Margate         41%    Partnership Interest       $ 2,624,000         $  262,400         $1,313,100             $1,048,500
 Margate, FL
Winter Haven           41%    Partnership Interest       $ 1,521,100         $  152,100         $  814,700             $  554,300
 Winter Haven, FL
Garden Walk            31%        Tenant in              $ 3,518,500         $  351,900         $1,767,000             $1,399,600
 Palm Beach                      Common/Joint            -----------         ----------         ----------             ----------
 Gardens, FL                   Venture Interest

         Total                                           $16,652,800         $1,214,700         $6,325,000             $9,113,100
                                                         ===========         ==========         ==========             ==========

</TABLE>

                            12

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