<PAGE>
                                                                    Exhibit 10.1


                         WALTHAM WESTON CORPORATE CENTER

                                 201 JONES ROAD
                             WALTHAM, MASSACHUSETTS

                          LEASE DATED August 27, 2002


      THIS INSTRUMENT IS AN INDENTURE OF LEASE in which the Landlord and the
Tenant are the parties hereinafter named, and which relates to space in a
certain building (the "Building") known as, and with an address at, 201 Jones
Road, Waltham, Massachusetts.

      The parties to this Indenture of Lease hereby agree with each other as
follows:

                                    ARTICLE I

                                 REFERENCE DATA

1.1   SUBJECTS REFERRED TO:

      Each reference in this Lease to any of the following subjects shall be
      construed to incorporate the data stated for that subject in this Article:

<TABLE>
<S>                                  <C>
      LANDLORD:                      STONY BROOK ASSOCIATES LLC, a
                                     Delaware limited liability company


      LANDLORD'S ORIGINAL            c/o Boston Properties Limited Partnership
      ADDRESS:                       111 Huntington Avenue, Suite 300
                                     Boston, Massachusetts 02199-7610

      LANDLORD'S CONSTRUCTION
      REPRESENTATIVE:                Jeff Lowenberg and Mark Denman

      TENANT:                        NETEGRITY, INC., a Delaware corporation

      TENANT'S ORIGINAL              52 Second Avenue
      ADDRESS:                       Waltham, Massachusetts 02154

      TENANT'S CONSTRUCTION
      REPRESENTATIVE:                Donna Burke
</TABLE>
<PAGE>
<TABLE>
<S>                                  <C>
      ESTIMATED TERM
      COMMENCEMENT DATE:             March 1, 2003

      COMMENCEMENT DATE:             As defined in Sections 2.4 and 3.2

      RENT COMMENCEMENT DATE:        The later to occur of (i) August 1, 2003
                                     and (ii) that date which is four (4) months
                                     from the Commencement Date.

      OUTSIDE COMPLETION DATE:       June 30, 2003

      TERM (SOMETIMES CALLED         Sixty-four (64) calendar months (plus
      THE "ORIGINAL TERM"):          the partial month, if any, immediately
                                     following the Commencement Date), unless
                                     extended or sooner terminated as provided
                                     in this Lease.

      EXTENSION OPTION:              One (1) period of five (5) years as
                                     provided in and on the terms set forth in
                                     Section 8.20 hereof.

      THE SITE:                      Those certain parcels of land in Waltham,
                                     Middlesex County, Massachusetts, being more
                                     particularly described in Exhibit A
                                     attached hereto.

      THE BUILDING:                  The Building known as and numbered 201
                                     Jones Road, Waltham, Massachusetts.  The
                                     Building is appropriately labeled on
                                     Exhibit A-1 attached hereto and hereby
                                     made a part hereof.

      THE COMPLEX:                   The Building together with all parking
                                     areas, decks and structures and the Site.

      TENANT'S SPACE:                The entire fifth (5th) floor of the
                                     Building in accordance with the floor plan
                                     annexed hereto as Exhibit D and
                                     incorporated herein by reference.

      NUMBER OF                      Two Hundred Eighteen (218)
      PARKING SPACES:

      ANNUAL FIXED RENT:             (a) For the period commencing on the Rent
                                     Commencement Date and ending on the last
</TABLE>


                                       2
<PAGE>
<TABLE>
<S>                                  <C>
                                     day of the twelfth (12th) full calendar
                                     month of the Original Term of this Lease at
                                     the annual rate of $1,359,575.00 (being the
                                     product of (i) $25.00 and (ii) the
                                     "Rentable Floor Area of Tenant's Space"
                                     (hereinafter defined in this Section 1.1

                                     (b) For the period commencing on the first
                                     day of the thirteenth (13th) full calendar
                                     month of the Original Term of this Lease
                                     and ending on the last day of the
                                     thirty-sixth (36th) full calendar month of
                                     the Original Term of this Lease, at the
                                     annual rate of $1,468,341.00 (being the
                                     product of $27.00 and (ii) the Rentable
                                     Floor Area of Tenant's Space).

                                     (c) For the period commencing on the first
                                     day of the thirty-seventh (37th) full
                                     calendar month of the Original Term of this
                                     Lease and ending on the last day of the
                                     Original Term of this Lease, at the annual
                                     rate of $1,522,724.00 (being the product
                                     of $28.00 and (ii) the Rentable Floor Area
                                     of Tenant's Space).

                                     (d) During the extension option period (if
                                     exercised), as determined pursuant to
                                     Section 8.20.

      BASE OPERATING EXPENSES:       Landlord's Operating Expenses (as
                                     hereinafter defined in Section 2.6) for
                                     calendar year 2003, being January 1, 2003
                                     through December 31, 2003.

      TENANT ELECTRICITY:            Initially as provided in Section 2.5
                                     subject to adjustment as provided in
                                     Section 2.8.

      ADDITIONAL RENT:               All charges and other sums payable by
                                     Tenant as set forth in this Lease, in
                                     addition to Annual Fixed Rent.
</TABLE>


                                       3
<PAGE>
<TABLE>
<S>                                  <C>
      RENTABLE FLOOR AREA
      OF TENANT'S SPACE
      (SOMETIMES ALSO
      CALLED RENTABLE FLOOR
      AREA OF THE PREMISES):         54,383 square feet.

      TOTAL RENTABLE FLOOR
      AREA OF THE BUILDING:          304,050 square feet.

      PERMITTED USE:                 General office purposes.

      INITIAL MINIMUM                $10,000,000.00 combined single limit per
      LIMITS OF TENANT'S             occurrence.
      COMMERCIAL GENERAL
      LIABILITY INSURANCE:

      BROKERS:                       The Columbia Group Realty Advisors
                                     50 Rowes Wharf
                                     Suite 420
                                     Boston, Massachusetts  02110

                                     CRF Partners, Inc.
                                     338 Main Street
                                     Wakefield, Massachusetts  01880

                                     Trammell Crow Company
                                     125 High Street
                                     Boston, Massachusetts 02110

      SECURITY DEPOSIT:              $679,787.50, subject to and in accordance
                                     with the terms and provision of Section
                                     8.21 below.
</TABLE>

1.2   EXHIBITS.  There are incorporated as part of this Lease:

      EXHIBIT A               Description of Site

      EXHIBIT A-1             Site Plan of Complex

      EXHIBIT B               Plan of Landlord's Work

      EXHIBIT B-1             Tenant's Submission

      EXHIBIT C               Landlord's Services


                                       4
<PAGE>
      EXHIBIT D               Floor Plan

      EXHIBIT E               Form of Commencement Date Agreement

      EXHIBIT F               Broker Determination

      EXHIBIT G               Notice of Lease

      1.3   TABLE OF ARTICLES AND SECTIONS

      ARTICLE I-REFERENCE DATA

      1.1   Subjects Referred to

      1.2   Exhibits

      1.3   Table of Articles and Sections

      ARTICLE II-BUILDING, PREMISES, TERM AND RENT

      2.1   The Premises

      2.1.1 Tenant's Expansion Options

      2.1.2 Tenant's Right of First Offer

      2.2   Rights To Use Common Facilities

      2.2.1 Tenant's Parking

      2.3   Landlord's Reservations

      2.4   Habendum

      2.5   Fixed Rent Payments

      2.6   Operating Expenses

      2.7   Real Estate Taxes

      2.8   Tenant Electricity

      ARTICLE III-CONDITION OF PREMISES; ALTERATIONS

      3.1   Substantial Completion


                                       5
<PAGE>
      3.2   Certain Tenant Rights

      3.3   General Provisions Applicable to Construction

      3.4   Intentionally Omitted

      3.5   Additional Tenant Work Costs

      3.6   Alterations

      ARTICLE IV-LANDLORD'S COVENANTS; INTERRUPTIONS AND DELAYS

      4.1   Landlord's Covenants

      4.1.1 Services Furnished by Landlord

      4.1.2 Additional Services Available to Tenant

      4.1.3 Roof, Exterior Wall, Floor Slab and Common Facility Repairs

      4.1.4 Door Signs

      4.2   Interruptions and Delays in Services and Repairs, etc.

      4.3   Landlord Insurance

      4.4   ADA Compliance

      ARTICLE V-TENANT'S COVENANTS

      5.1   Payments

      5.2   Repair and Yield Up

      5.3   Use

      5.4   Obstructions; Items Visible From Exterior; Rules and Regulations

      5.5   Safety Appliances; Licenses

      5.6   Assignment; Sublease

      5.7   Indemnity; Insurance


                                       6
<PAGE>
      5.8   Personal Property at Tenant's Risk

      5.9   Right of Entry

      5.10  Floor Load; Prevention of Vibration and Noise

      5.11  Personal Property Taxes

      5.12  Compliance with Laws

      5.13  Payment of Litigation Expenses

      ARTICLE VI-CASUALTY AND TAKING

      6.0   Landlord's Restoration Estimate

      6.1   Damage Resulting from Casualty

      6.2   Uninsured Casualty

      6.3   Rights of Termination for Taking

      6.4   Award

      ARTICLE VII-DEFAULT

      7.1   Tenant's Default

      7.2   Landlord's Default

      ARTICLE VIII-MISCELLANEOUS PROVISIONS

      8.1   Extra Hazardous Use

      8.2   Waiver

      8.3   Cumulative Remedies

      8.4   Quiet Enjoyment

      8.5   Notice To Mortgagee and Ground Lessor

      8.6   Assignment of Rents

      8.7   Surrender


                                       7
<PAGE>
      8.8   Brokerage

      8.9   Invalidity of Particular Provisions

      8.10  Provisions Binding, Etc.

      8.11  Recording

      8.12  Notices

      8.13  When Lease Becomes Binding

      8.14  Section Headings

      8.15  Rights of Mortgagee

      8.16  Status Reports and Financial Statements

      8.17  Self-Help

      8.18  Holding Over

      8.19  Non-Subrogation

      8.20  Extension Option

      8.21  Security Deposit

      8.22  Late Payment

      8.23  Tenant's Payments

      8.24  Waiver of Trial by Jury

      8.25  Governing Law

                                   ARTICLE II

                        BUILDING, PREMISES, TERM AND RENT

2.1   THE PREMISES. Landlord hereby demises and leases to Tenant, and Tenant
      hereby hires and accepts from Landlord, Tenant's Space in the Building
      excluding exterior faces


                                       8
<PAGE>
      of exterior walls, the common stairways and stairwells, elevators and
      elevator wells, fan rooms, electric and telephone closets, janitor
      closets, freight elevator vestibules, and pipes, ducts, conduits, wires
      and appurtenant fixtures serving exclusively or in common other parts of
      the Building and if Tenant's Space includes less than the entire rentable
      area of any floor, excluding the common corridors, elevator lobbies and
      toilets located on such floor. Subject to events beyond Landlord's
      reasonable control, Tenant shall have access to the Premises, including
      elevator access, twenty-four (24) hours per day, seven (7) days per week.

      Tenant's Space with such exclusions is hereinafter referred to as the
      "Premises". The term "Building" means the Building identified on the first
      page, and which is the subject of this Lease; the term "Site" means all,
      and also any part of the Land described in Exhibit A, plus any additions
      or reductions thereto resulting from the acquisition of adjacent property
      by Landlord or from the change of any abutting street line and all parking
      areas and structures. The term "Property" means the Building and the Site.

2.1.1 TENANT'S EXPANSION OPTIONS. (A) Upon written notice to be given by Tenant
      to Landlord no later than October 1, 2003 ("Tenant's First Expansion
      Notice") Tenant shall have the right to lease an additional 5,000 to
      10,000 square feet of rentable floor area located on either the first,
      second, third or fourth floor of the Building ("Expansion Premises A"), it
      being understood and agreed that the actual location and square footage of
      Expansion Premises A shall be determined by Landlord in its sole
      discretion after receipt by Landlord of Tenant's First Expansion Notice.
      Expansion Premises A shall be delivered to Tenant between January 1, 2004
      and June 30, 2004 (the "Expansion Premises A Delivery Date"), which date
      shall be determined by Landlord in its sole discretion. Effective as of
      the Expansion Premises A Delivery Date, for the remainder of the Term of
      this Lease (including any extension thereof), Expansion Premises A shall
      be automatically added to the Premises demised under this Lease upon all
      the same terms and conditions applicable to the Premises (including,
      without limitation, the rate of Annual Fixed Rent and the provisions for
      payment of operating expenses, real estate taxes and electricity as set
      forth below), except as expressly provided to the contrary in the next
      paragraph of this subsection (A), and from and after the Expansion
      Premises A Delivery Date the Rentable Floor Area of the Premises shall be
      increased by the rentable floor area of Expansion Premises A. Landlord and
      Tenant shall enter into an instrument amending this Lease to memorialize
      the addition of Expansion Premises A no later than thirty (30) days after
      the Expansion Premises A Delivery Date, provided, however, that the
      failure to enter into such an instrument shall not affect the addition of
      Expansion Premises A to the Premises.

      Notwithstanding anything contained herein to the contrary, (i) in the
      event that Expansion Premises A is in "shell" condition, Landlord shall,
      at Landlord's sole cost and expense, deliver said Expansion Premises A to
      Tenant in substantially the same condition as the Premises are being
      delivered to Tenant in accordance with Article III below, and (ii) in the
      event that Expansion Premises A has previously been built out, Landlord
      shall (x) patch and repaint Expansion Premises A with one coat of paint in
      the then-existing color


                                       9
<PAGE>
      of such Expansion Premises A and (ii) perform minor repartitioning work in
      Expansion Premises A at a cost not to exceed $25,000.00, it being
      understood and agreed that Tenant shall be responsible for all costs of
      repartitioning work above $25,000.00 (provided, however, that Tenant shall
      have the option of accepting Expansion Premises A in their "as-is"
      condition without any obligation on Landlord's part to perform any
      additions, alterations, improvements or other work therein or pertaining
      thereto, and without any cost or expense to Landlord or Tenant).

      (B) Upon written notice to be given by Tenant to Landlord no later than
      September 1, 2004 ("Tenant's Second Expansion Notice"), Tenant shall have
      the right to lease an additional 10,000 to 25,000 square feet of rentable
      floor area located on either the first, second, third or fourth floor of
      the Building ("Expansion Premises B"). Expansion Premises B shall be
      delivered to Tenant between July 1, 2005 and December 31, 2005 (the
      "Expansion Premises B Delivery Date"), which date shall be determined by
      Landlord in its sole discretion. Within twenty (20) days after the date of
      Tenant's Second Expansion Notice, Landlord shall advise Tenant of (i) the
      actual location and square footage of Expansion Premises B (which shall be
      determined by Landlord in its sole discretion) and the Expansion Premises
      B Delivery Date, (ii) the annual fair market rent for such space as of the
      Expansion Premises B Delivery Date based upon the use of such space as
      first class office space and the location of such space in the Building
      utilizing properties of similar character in the Boston West Suburban
      Market (the "Expansion Premises B Annual Market Rent") and (iii) the other
      business terms upon which Expansion Premises B is to be made available to
      Tenant (said notice from Landlord being hereinafter referred to as
      "Landlord's Expansion Premises B Terms Notice").

      Within ten (10) days after receipt of Landlord's Expansion Premises B
      Terms Notice, Tenant shall provide Landlord with written notice (x) of
      Tenant's agreement with and acceptance of the terms set forth in
      Landlord's Expansion B Premises Terms Notice or (y) requesting a broker
      determination of the "Prevailing Market Rent" and other business terms and
      conditions for such space (the "Expansion Premises B Broker
      Determination"), to be made in the manner set forth in Exhibit F or (z)
      revoking its exercise of Tenant's Second Expansion Notice. If Tenant shall
      give the notice specified in subsection (x) above, then Expansion Premises
      B shall be incorporated into the Premises as of the Expansion Premises B
      Delivery Date upon all of the same terms and conditions contained in this
      Lease, except for the provisions of this Section 2.1.1(B), the Annual
      Fixed Rent for such space (which shall be equal to the Expansion Premises
      B Annual Market Rent as quoted by Landlord) and those provisions which are
      inconsistent with the terms of Landlord's Expansion Premises B Terms
      Notice. If Tenant shall have given the notice specified in subsection (y)
      above requesting the Expansion Premises B Broker Determination, then
      Expansion Premises B shall be incorporated into the Premises as of the
      Expansion Premises B Delivery Date upon all of the same terms and
      conditions contained in this Lease, except for the provisions of this
      Section 2.1.1(B) and the Annual Fixed Rent and other business terms and
      conditions for such space (which shall be as determined by the Expansion
      Premises B Broker Determination). From and after the Expansion Premises B
      Delivery Date the Rentable Floor Area of the Premises shall be


                                       10
<PAGE>
      increased by the rentable floor area of Expansion Premises B. Landlord and
      Tenant shall enter into an instrument amending this Lease to memorialize
      the addition of Expansion Premises B within thirty (30) days after the
      Expansion Premises B Delivery Date, provided, however, that the failure to
      enter into such an instrument shall not affect the addition of Expansion
      Premises B to the Premises. If Tenant shall have given the notice
      specified in subsection (z) above revoking its exercise of Tenant's Second
      Expansion Notice, then the provisions of this Section 2.1.1(B) shall be
      null and void and of no further force and effect and Tenant shall have no
      further rights with respect to Expansion Premises B (except as may be set
      forth in Section 2.1.2 below).

      Notwithstanding anything contained in this Lease to the contrary, it is
      understood and agreed that in the event Tenant shall exercise its option
      to lease Expansion Premises B as set forth in this Section 2.1.1(B), the
      Term of this Lease for the entire Premises (i.e. the Premises, Expansion
      Premises A if Tenant has leased the same and Expansion Premises B, but not
      including any First Offer Space as defined in Section 2.1.2 below) shall
      be adjusted to create a new term commencing on the Expansion Premises B
      Delivery Date and expiring on the last day of the sixtieth (60th) full
      calendar month immediately following the Expansion Premises B Delivery
      Date (the "Adjusted Term") (it being understood and agreed that Tenant's
      right to extend the Term of this Lease as set forth in Section 8.20 hereof
      would thereafter apply to the entire Premises as described above and would
      be exercisable upon the expiration of the Adjusted Term). Annual Fixed
      Rent and Additional Rent with respect to the Premises and Expansion
      Premises A would continue to be payable at the rates set forth in this
      Lease with respect to that portion of the Adjusted Term as would otherwise
      have constituted the remainder of the Original Term of this Lease;
      provided, however, that upon what would have otherwise been the expiration
      of the Original Term of this Lease with respect to the Premises and
      Expansion Premises A and for the remainder of the Adjusted Term, Annual
      Fixed Rent and Additional Rent with respect to such space shall be payable
      at the same rates as applicable to Expansion Premises B as determined in
      accordance with the provisions of this Section 2.1.1(B).

      (C) Time is of the essence in the delivery by Tenant of Tenant's First
      Expansion Notice and Tenant's Second Expansion Notice. It is understood
      and agreed that Tenant's rights as set forth in this Section 2.1.1 shall
      only be available to the extent that at the time Tenant exercises its
      option and upon the delivery of the applicable expansion premises to
      Tenant (i) Tenant is not then in default in the performance of any of its
      obligations under this Lease beyond any applicable notice and cure
      periods, (ii) Tenant has not assigned this Lease nor sublet in the
      aggregate thirty-three percent (33%) or more of the Rentable Floor Area of
      the Premises (except for an assignment or subletting permitted without
      Landlord's consent under Section 5.6.1 hereof) and (iii) this Lease is
      still in full force and effect. It is further understood and agreed that
      Tenant's rights as set forth in subsection (A) and (B) above shall be
      independent of each other, such that Tenant shall have the right to lease
      Expansion Premises B even if it had not previously exercised its option to
      lease Expansion Premises A.


                                       11
<PAGE>
2.1.2 TENANT'S RIGHT OF FIRST OFFER. (A) As of the date hereof, the fourth (4th)
      floor of the Building (the "First Offer Space") is currently unoccupied.
      Landlord shall have the right to market and lease such First Offer Space
      to third parties (the "Initial Tenants") in Landlord's sole discretion.
      Any such leases and the terms thereof, including, but not limited to, the
      original terms, any options to extend the terms, any expansion rights or
      options and any amendments thereto are hereinafter called the "Initial
      Leases". Subject to the Initial Leases and the rights of the Initial
      Tenants thereunder, which rights are prior to the offer right of Tenant
      under this Section 2.1.2 and notwithstanding that amendments to Initial
      Leases may be executed by the Initial Tenants subsequent to the date of
      this Lease, and provided that at the time any portion of the First Offer
      Space becomes available for leasing (i) there is no "Event of Default" (as
      defined in Section 7.1), (ii) Tenant has not assigned this Lease or sublet
      in the aggregate thirty-three percent (33%) or more of the Rentable Floor
      Area of the Premises (except for an assignment or subletting permitted
      without Landlord's consent under Section 5.6.1 hereof) and (iii) this
      Lease is still in full force and effect, Landlord agrees not to enter into
      a lease or leases to relet any portion of the First Offer Space on or
      after October 1, 2004 without first giving to Tenant an opportunity to
      lease such space on the terms and conditions hereinafter provided. If such
      space becomes so available for reletting, Landlord shall notify Tenant of
      the availability of such space ("Landlord's Offer Notice") and shall
      advise Tenant of the annual fair market rent for such space as of the date
      when the same becomes so available for reletting based upon the use of
      such space as first class office space and the location of such space in
      the Building utilizing properties of similar character within the Boston
      West Suburban Market and other business terms upon which Landlord is
      willing to lease such space (collectively, the "First Offer Space Terms
      and Conditions").

      (B) If Tenant wishes to exercise Tenant's right of offer, Tenant shall do
      so, if at all, by giving Landlord notice within fifteen (15) business days
      after receipt of Landlord's Offer Notice, time being of the essence, (i)
      of Tenant's desire to lease such space on the terms set forth in
      Landlord's Offer Notice or (ii) requesting a broker determination of the
      "Prevailing Market Rent" and other business terms and conditions for such
      space (the "First Offer Space Broker Determination"), to be made in the
      manner set forth in Exhibit F.

      (C) If Tenant timely shall give the notice specified in subsection (B)(i)
      hereinabove, the same shall constitute an agreement to enter into an
      amendment to this Lease to incorporate such space into the Premises within
      twenty (20) days thereafter, upon all of the same terms and conditions
      contained in this Lease, except for the provisions of this Section 2.1.2,
      the Annual Fixed Rent and other business terms and conditions for such
      space (which shall be the First Offer Space Terms and Conditions as quoted
      by Landlord) and those provisions which are inconsistent with the terms of
      Landlord's Offer Notice. If Tenant timely shall have given the notice
      specified in subsection (B) (ii) above requesting the First Offer Space
      Broker Determination, then in order to exercise its right of first offer,
      Tenant, within fifteen (15) business days after receipt of the First Offer
      Space Broker Determination, shall give written notice to Landlord of
      Tenant's exercise of its right of offer pursuant to this Section, in which
      case the Annual Fixed Rent and other


                                       12
<PAGE>
      business terms and conditions for such space shall be as determined by the
      First Offer Space Broker Determination. Upon the giving of notice by
      Tenant within said fifteen (15) day period as provided in this subsection
      then the same shall constitute an agreement to enter into an amendment to
      this Lease to incorporate such space into the Premises within twenty (20)
      days thereafter upon all the same terms, conditions, covenants and
      agreements contained in this Lease, except for the provisions of this
      Section 2.1.2, the Annual Fixed Rent and other business terms and
      conditions for such space which shall be determined as described in this
      subsection and those provisions which are consistent with the terms of
      Landlord's Offer Notice.

      (D) If Tenant shall not so exercise such right to lease such space within
      the periods specified in subsections (B) or (C) above, as applicable, time
      being of the essence in respect of such exercise, Tenant shall have no
      further right of offer hereunder with respect to that portion of the First
      Offer Space then being offered for lease (it being understood that
      Tenant's right of first offer shall be a one time right only) and Landlord
      shall be free to enter into a lease or leases of such space with another
      prospective tenant or tenants upon such terms and conditions as Landlord
      shall determine, which terms may include rights for options to extend the
      term or to expand the size of the premises under such lease or leases;
      provided, however, that if following the date of Landlord's Offer Notice,
      Landlord proposes to lease the applicable portion of the First Offer Space
      at a rental rate that is equal to or less than ninety-five percent (95%)
      of the rental rate set forth in Landlord's Offer Notice, the terms of this
      Section 2.1.2 shall continue to apply to such portion of the First Offer
      Space.

      (E) If Tenant shall exercise any such right of first offer and if,
      thereafter, the then occupant of the premises with respect to which Tenant
      shall have so exercised such right wrongfully fails to deliver possession
      of such premises at the time when its tenancy is scheduled to expire,
      commencement of the term of Tenant's occupancy and lease of such
      additional space shall, in the event of such holding over by such
      occupant, be deferred until possession of the additional space is
      delivered to Tenant and no rent shall be due on such additional space
      until the same is delivered to Tenant. The failure of the then occupant of
      such premises to so vacate, shall not give Tenant any right to terminate
      this Lease or to deduct from, offset against or withhold Annual Fixed Rent
      or additional rent or other charges payable under this Lease or any
      portions thereof. Notwithstanding the foregoing, Tenant shall have the
      right to rescind its exercise of its right of first offer hereunder in the
      event that Landlord shall fail to deliver the applicable portion of the
      First Offer Space within six (6) months from the delivery date set forth
      in Landlord's Offer Notice, which such rescission shall be set forth in a
      notice given by Tenant to Landlord no later than fifteen (15) days from
      the expiration of the aforesaid six-month period.

      (F) It is understood and agreed that Tenant's rights as set forth in this
      Section 2.1.2 shall be independent of its rights as set forth in Section
      2.1.1 above, such that Tenant shall have the right to lease the First
      Offer Space regardless of whether or not it has exercised its rights to
      lease Expansion Premises A and/or Expansion Premises B.


                                       13
<PAGE>
2.2   RIGHTS TO USE COMMON FACILITIES. Subject to Landlord's right to change or
      alter any of the following in Landlord's discretion as herein provided,
      Tenant shall have, as appurtenant to the Premises, the non- exclusive
      right to use in common with others, subject to reasonable rules of general
      applicability to tenants of the Building from time to time made by
      Landlord of which Tenant is given notice (a) the common lobbies,
      corridors, stairways, elevators and loading platform of the Building, and
      the pipes, ducts, conduits, wires and appurtenant meters and equipment
      serving the Premises in common with others, (b) common walkways and
      driveways necessary for access to the Building, (c) if the Premises
      include less than the entire rentable floor area of any floor, the common
      toilets, corridors and elevator lobby of such floor, and (d) the cafeteria
      and fitness center serving the Building. Notwithstanding anything to the
      contrary herein, Landlord has no obligation to allow any particular
      telecommunication service provider to have access to the Building or to
      the Premises except as may be required by applicable law. If Landlord
      permits such access, Landlord may condition such access upon the payment
      to Landlord by the service provider of fees assessed by Landlord in its
      sole discretion.

2.2.1 TENANT'S PARKING. In addition, Tenant shall have the right, free of charge
      during the Original Term of this Lease, to use in the parking area the
      Number of Parking Spaces (referred to in Section 1.1, which such Number of
      Parking Spaces shall be increased proportionately to reflect any increases
      in the Rentable Floor Area of the Premises) for the parking of
      automobiles, in common with use by other tenants from time to time of the
      Complex, provided, however, that Landlord shall not be obligated to
      furnish stalls or spaces on the Site specifically designated for Tenant's
      use. Tenant covenants and agrees that it and all persons claiming by,
      through and under it, shall at all times abide by all reasonable rules and
      regulations of general application promulgated by Landlord with respect to
      the use of the parking areas on the Site. The parking privileges granted
      herein are non-transferable except to a permitted assignee or subtenant as
      provided in Section 5.6 through Section 5.6.5. Further, Landlord assumes
      no responsibility whatsoever for loss or damage due to fire, theft or
      otherwise to any automobile(s) parked on the Site or to any personal
      property therein, however caused (except to the extent caused by the
      negligence or willful misconduct of Landlord or its agents, employees or
      contractors), and Tenant covenants and agrees, upon request from Landlord
      from time to time, to notify its officers, employees, agents and invitees
      of such limitation of liability. Tenant acknowledges and agrees that a
      license only is hereby granted, and no bailment is intended or shall be
      created.

2.3   LANDLORD'S RESERVATIONS. Landlord reserves the right from time to time,
      without unreasonable interference with Tenant's use and with no material
      reduction in the usable floor area of the Premises: (a) to install, use,
      maintain, repair, replace and relocate for service to the Premises and
      other parts of the Building, or either, pipes, ducts, conduits, wires and
      appurtenant fixtures, wherever located in the Premises or Building, and
      (b) to alter or relocate any other common facility, provided that
      substitutions are substantially equivalent or better. Installations,
      replacements and relocations referred to in clause (a) above shall be
      located so far as practicable in the central core area of the


                                       14
<PAGE>
      Building, above ceiling surfaces, below floor surfaces or within perimeter
      walls of the Premises.

2.4   HABENDUM. Tenant shall have and hold the Premises for a period commencing
      on the earlier of (a) that date on which the Premises are ready for
      occupancy as in Section 3.1 provided, or (b) that date on which Tenant
      commences occupancy of any portion of the Premises for the Permitted Uses,
      and continuing for the Term unless sooner terminated as provided in
      Article VI or Article VII or unless extended as provided in Section 8.20.

      As soon as may be convenient after the date has been determined on which
      the Term commences as aforesaid, Landlord and Tenant agree to join with
      each other in the execution of a written Declaration, in the form of
      Exhibit E, in which the date on which the Term commences as aforesaid and
      the Term of this Lease shall be stated. If Tenant fails to execute such
      Declaration, the Commencement Date and Lease Term shall be as reasonably
      determined by Landlord in accordance with the terms of this Lease.

2.5   FIXED RENT PAYMENTS. Tenant agrees to pay to Landlord, or as directed by
      Landlord, at Landlord's Original Address specified in Section 1.1 hereof,
      or at such other place as Landlord shall from time to time designate by
      notice, (1) (a) on the Rent Commencement Date (defined in Section 1.1
      hereof) and thereafter monthly, in advance, on the first day of each and
      every calendar month during the Original Term, a sum equal to one twelfth
      (1/12th) of the Annual Fixed Rent (sometimes hereinafter referred to as
      "fixed rent") and (b) on the Commencement Date and thereafter monthly, in
      advance, on the first day of each and every calendar month during the
      Original Term, a sum equal to one twelfth (1/12th) of $1.00 per annum for
      each square foot of Rentable Floor Area of Tenant's Space for tenant
      electricity subject to escalation as provided in Section 2.8 and (2) on
      the first day of each and every calendar month during the extension option
      period (if exercised), a sum equal to (a) one twelfth (1/12th) of the
      annual fixed rent as determined in Section 8.20 for the extension option
      period plus (b) then applicable monthly electricity charges (subject to
      escalation for electricity as provided in Section 2.8 hereof). Until
      notice of some other designation is given, fixed rent and all other
      charges for which provision is herein made shall be paid by remittance to
      or for the order of Boston Properties Limited Partnership at P.O. Box
      3557, Boston, Massachusetts 02241-3557, and all remittances received by
      Boston Properties Limited Partnership, as Agents as aforesaid, or by any
      subsequently designated recipient, shall be treated as payment to
      Landlord.

      Annual Fixed Rent for any partial month shall be paid by Tenant to
      Landlord at such rate on a pro rata basis, and, if the Rent Commencement
      Date is a day other than the first day of a calendar month, the first
      payment of Annual Fixed Rent which Tenant shall make to Landlord shall be
      a payment equal to a proportionate part of such monthly Annual Fixed Rent
      for the partial month from the Rent Commencement Date to the first day of
      the succeeding calendar month.


                                       15
<PAGE>
      Additional Rent payable by Tenant on a monthly basis, as hereinafter
      provided, likewise shall be prorated, and the first payment on account
      thereof shall be determined in similar fashion but shall commence on the
      Commencement Date; and other provisions of this Lease calling for monthly
      payments shall be read as incorporating this undertaking by Tenant.

      Notwithstanding that the payment of Annual Fixed Rent payable by Tenant to
      Landlord shall not commence until the Rent Commencement Date, Tenant shall
      be subject to, and shall comply with, all other provisions of this Lease
      as and at the times provided in this Lease.

      The Annual Fixed Rent and all other charges for which provision is herein
      made shall be paid by Tenant to Landlord, without offset, deduction or
      abatement except as otherwise specifically set forth in this Lease.

2.6   OPERATING EXPENSES. "Landlord's Operating Expenses" means the cost of
      operation of the Building and the Site which shall exclude costs of
      special services rendered to tenants (including Tenant) and tenant
      electricity for which a separate charge is made, but shall include,
      without limitation, the following: premiums for insurance carried with
      respect to the Building and the Site (including, without limitation,
      liability insurance, insurance against loss in case of fire or casualty
      and insurance of monthly installments of fixed rent and any Additional
      Rent which may be due under this Lease and other leases of space in the
      Building for not more than 12 months in the case of both fixed rent and
      Additional Rent and if there be any first mortgage of the Property,
      including such insurance as may be required by the holder of such first
      mortgage); compensation and all fringe benefits, worker's compensation
      insurance premiums and payroll taxes paid to, for or with respect to all
      persons engaged in the operating, maintaining or cleaning of the Building
      or Site, water, sewer, electric, gas, oil and telephone charges (excluding
      utility charges separately chargeable to tenants for additional or special
      services); cost of building and cleaning supplies and equipment; cost of
      maintenance, cleaning and repairs (other than repairs not properly
      chargeable against income or reimbursed from contractors under
      guarantees); cost of snow removal and care of landscaping; payments under
      service contracts with independent contractors; cost of operating,
      maintaining and cleaning the cafeteria and fitness center serving the
      Building; management fees at reasonable rates consistent with the type of
      occupancy and the service rendered; and all other reasonable and necessary
      expenses paid in connection with the operation, cleaning and maintenance
      of the Building and the Site and properly chargeable against income,
      provided, however, there shall be included (a) depreciation for capital
      expenditures made by Landlord (i) to reduce Landlord's Operating Expenses
      if Landlord shall have reasonably determined that the annual reduction in
      Landlord's Operating Expenses shall exceed depreciation therefor and
      interest thereon or (ii) to comply with applicable laws, rules,
      regulations, requirements, statutes, ordinances, by-laws and court
      decisions of all public authorities which are hereafter in force; plus (b)
      in the case of both (i) and (ii) an interest factor, reasonably determined
      by Landlord, as being the interest rate then charged for long term
      mortgages by institutional lenders on


                                       16
<PAGE>
      like properties within the locality in which the Building is located;
      depreciation in the case of both (i) and (ii) shall be determined by
      dividing the original cost of such capital expenditure by the number of
      years of useful life of the capital item acquired and the useful life
      shall be reasonably determined by Landlord in accordance with generally
      accepted accounting principles and practices in effect at the time of
      acquisition of the capital item.

      Notwithstanding the foregoing provisions, the following shall be excluded
      from Landlord's Operating Expenses:

      (1)   Leasing fees or commissions, advertising and promotional expenses,
            legal fees, the cost of tenant improvements, build out allowances,
            moving expenses, and other concessions incurred in connection with
            leasing spacing in the Building;

      (2)   Interest on indebtedness, debt amortization, ground rent, and
            refinancing costs for any mortgage or ground lease of the Building
            or the Site;

      (3)   Expenses incurred in obtaining a tax refund and abatement which have
            otherwise been paid by Tenant pursuant to Section 2.7;

      (4)   Costs incurred in performing work or finishing services for any
            tenant (including Tenant), whether at such tenant's or Landlord's
            expense, to the extent that such work or services is in excess or
            any work or service the Landlord is obligated to furnish to Tenant
            at Landlord's expense;

      (5)   The cost of any item or service to the extent to which Landlord is
            reimbursed or compensated by insurance, any tenant, or any third
            party;

      (6)   The cost of repairs or replacements incurred by reason of fire or
            other casualty or condemnation other than costs not in excess of the
            deductible on any insurance maintained by Landlord which provides a
            recovery for such repair or replacement;

      (7)   Any advertising, promotional or marketing expenses for the Building;

      (8)   With the exception of the management fee described in the first
            paragraph of this Section 2.6, the cost of any service or materials
            provided by any party related to Landlord, to the extent such costs
            exceed the reasonable cost for such service or materials absent such
            relationship in buildings similar to the Building in the vicinity of
            the Building;

      (9)   Penalties and interest for late payment of any obligations of
            Landlord, including, without limitation, taxes, insurance, equipment
            leases and other past due amounts;

      (10)  Salaries or other compensation paid to employees above the grade of
            Building manager;


                                       17
<PAGE>
      (11)  Cost of installing sculpture, paintings or other objects of art;

      (12)  Cost of repairs, replacements, alterations or improvements necessary
            to make the Building comply with applicable law as of the date of
            this Lease;

      (13)  Legal fees or other expenses incurred in connection with negotiating
            and enforcing leases with tenants in the Building; and

      (14)  Depreciation except as specifically otherwise expressly provided in
            this Lease.

      "Operating Expenses Allocable to the Premises" shall mean the same
      proportion of Landlord's Operating Expenses for and pertaining to the
      Building and the Site as the Rentable Floor Area of Tenant's Space bears
      to the Total Rentable Floor Area of the Building.

      "Base Operating Expenses" is hereinbefore defined in Section 1.1. Base
      Operating Expenses shall not include utility increases due to
      extraordinary circumstances, including, but not limited to, conservation
      surcharges, boycotts, embargoes or other shortages.

      "Base Operating Expenses Allocable to the Premises" means the same
      proportion of Base Operating Expenses for and pertaining to the Building
      and the Site as the Rentable Floor Area of Tenant's Space bears to the
      Total Rentable Floor Area of the Building.

      If with respect to any calendar year falling within the Term, or fraction
      of a calendar year falling within the Term at the beginning or end
      thereof, the Operating Expenses Allocable to the Premises for a full
      calendar year exceed Base Operating Expenses Allocable to the Premises, or
      for any such fraction of a calendar year exceed the corresponding fraction
      of Base Operating Expenses Allocable to the Premises, then Tenant shall
      pay to Landlord, as Additional Rent, the amount of such excess. Such
      payments shall be made at the times and in the manner hereinafter provided
      in this Section 2.6. (Base Operating Expenses Allocable to the Premises
      referred to above do not include the $1.00 for tenant electricity to be
      paid by Tenant at the time of payment of Annual Fixed Rent and for which
      provision is made in Section 2.5 hereof, separate provision being made in
      Section 2.8 of this Lease for Tenant's share of increases in electricity
      costs.)

      Not later than one hundred and twenty (120) days after the end of the
      first calendar year or fraction thereof ending December 31 and of each
      succeeding calendar year during the Term or fraction thereof at the end of
      the Term, Landlord shall render Tenant a statement in reasonable detail
      and according to usual accounting practices certified by a representative
      of Landlord, showing for the preceding calendar year or fraction thereof,
      as the case may be, Landlord's Operating Expenses and Operating Expenses
      Allocable to the Premises. Said statement to be rendered to Tenant shall
      also show for the preceding year or fraction thereof as the case may be
      the amounts of operating expenses already paid by Tenant as Additional
      Rent, and the amount of operating expenses remaining due from, or


                                       18
<PAGE>
      overpaid by, Tenant for the year or other period covered by the statement.
      Within thirty (30) days after the date of delivery of such statement,
      Tenant shall pay to Landlord the balance of the amounts, if any, required
      to be paid pursuant to the above provisions of this Section 2.6 with
      respect to the preceding year or fraction thereof, or Landlord shall
      credit any amounts due from it to Tenant pursuant to the above provisions
      of this Section 2.6 against (i) monthly installments of fixed rent next
      thereafter coming due or (ii) any sums then due from Tenant to Landlord
      under this Lease (or refund within thirty (30) days such portion of the
      overpayment as aforesaid if the Term has ended and Tenant has no further
      obligation to Landlord). Upon no less than five (5) business days prior
      notice to Landlord, Tenant, at Tenant's expense, may examine Landlord's
      books and records regarding such statement at a mutually agreeable time
      during Landlord's business hours at a place designated by Landlord, but
      Landlord need not retain such books or records for more than three (3)
      years after the close of the applicable calendar year. In the event such
      examination reveals a discrepancy between such statement and Landlord's
      Operating Expenses, Tenant shall provide Landlord written notice thereof
      within thirty (30) days of the examination. Within a reasonable time
      following Landlord's receipt of such notice not to exceed thirty (30)
      days, Landlord shall have the right to verify such discrepancy as stated
      in Tenant's notice, and if Landlord reasonably determines such discrepancy
      shall exist, Landlord shall provide Tenant notice confirming the amount of
      the refund due to Tenant or payment due to Landlord, as applicable, due to
      such discrepancy. The failure by Landlord to respond to Tenant's notice
      within the aforesaid thirty (30) day period shall be deemed to be a
      confirmation by Landlord of such discrepancy. Within thirty (30) days of
      Tenant's receipt of such notice, the amount due to such discrepancy shall
      be refunded to Tenant or paid to Landlord, as applicable. In addition, in
      the event there is a discrepancy between Landlord's statement and
      Landlord's Operating Expenses exceeding five percent (5%), Landlord shall
      reimburse Tenant for Tenant's reasonable fees paid by Tenant for the
      examination of Landlord's books and records in an amount not to exceed
      $5,000.00. Tenant shall hold such books, records and other information
      gathered from such examination in confidence and not disclose the same to
      any other party, including, without limitation, any other tenant in the
      Building.

      In addition, Tenant shall make payments monthly on account of Tenant's
      share of increases in Landlord's Operating Expenses anticipated for the
      then current year at the time and in the fashion herein provided for the
      payment of fixed rent. The amount to be paid to Landlord shall be an
      amount reasonably estimated annually by Landlord to be sufficient to
      cover, in the aggregate, a sum equal to Tenant's share of such increases
      in operating expenses for each calendar year during the Term.

      Notwithstanding the foregoing provisions, no decrease in Landlord's
      Operating Expenses shall result in a reduction of the amount otherwise
      payable by Tenant if and to the extent said decrease is attributable to
      vacancies in the Buildings rather than to any other causes.

2.7   REAL ESTATE TAXES. If with respect to any full Tax Year or fraction of a
      Tax Year falling within the Term, Landlord's Tax Expenses Allocable to the
      Premises as hereinafter defined for a full Tax Year exceed $3.75 per
      square foot of Rentable Floor Area of the


                                       19
<PAGE>
      Premises, or for any such fraction of a Tax Year exceed the corresponding
      fraction of $3.75 per square foot of Rentable Floor Area of the Premises,
      then Tenant shall pay to Landlord, as Additional Rent, the amount of such
      excess. Not later than ninety (90) days after Landlord's Tax Expenses
      Allocable to the Premises are determined for the first such Tax Year or
      fraction thereof and for each succeeding Tax Year or fraction thereof
      during the Term, Landlord shall render Tenant a statement in reasonable
      detail certified by a representative of Landlord showing for the preceding
      year or fraction thereof, as the case may be, real estate taxes on the
      Building and the Site and abatements and refunds of any taxes and
      assessments. Expenditures for legal fees and for other expenses incurred
      in obtaining the tax refund or abatement may be charged against the tax
      refund or abatement before the adjustments are made for the Tax Year. Said
      statement to be rendered to Tenant shall also show for the preceding year
      or fraction thereof as the case may be the amounts of real estate taxes
      already paid by Tenant as Additional Rent, and the amount of real estate
      taxes remaining due from, or overpaid by, Tenant for the year or other
      period covered by the statement. Within thirty (30) days after the date of
      delivery of the foregoing statement, Tenant shall pay to Landlord the
      balance of the amounts, if any, required to be paid pursuant to the above
      provisions of this Section 2.7 with respect to the preceding year or
      fraction thereof, or Landlord shall credit any amounts due from it to
      Tenant pursuant to the provisions of this Section 2.7 against (i) monthly
      installments of fixed rent next thereafter coming due or (ii) any sums
      then due from Tenant to Landlord under this Lease (or refund within thirty
      (30) days such portion of the over-payment as aforesaid if the Term has
      ended and Tenant has no further obligation to Landlord).

      In addition, payments by Tenant on account of increases in real estate
      taxes anticipated for the then current year shall be made monthly at the
      time and in the fashion herein provided for the payment of fixed rent. The
      amount so to be paid to Landlord shall be an amount reasonably estimated
      by Landlord to be sufficient to provide Landlord, in the aggregate, a sum
      equal to Tenant's share of such increases, at least ten (10) days before
      the day on which such payments by Landlord would become delinquent.

      To the extent that real estate taxes shall be payable to the taxing
      authority in installments with respect to periods less than a Tax Year,
      the foregoing statement shall be rendered and payments made on account of
      such installments. Notwithstanding the foregoing provisions, no decrease
      in Landlord's Tax Expenses with respect to any Tax Year shall result in a
      reduction of the amount otherwise payable by Tenant if and to the extent
      said decrease is attributable to vacancies in the Building or partial
      completion of the Building rather than to any other causes.

      Terms used herein are defined as follows:

(i)   "Tax Year" means the twelve-month period beginning July 1 each year during
      the Term or if the appropriate governmental tax fiscal period shall begin
      on any date other than July 1, such other date.


                                       20
<PAGE>
            (ii)  "Landlord's Tax Expenses Allocable to the Premises" shall mean
                  the same proportion of Landlord's Tax Expenses for and
                  pertaining to the Building and the Site as the Rentable Floor
                  Area of Tenant's Space bears to the Total Rentable Floor Area
                  of the Building.

            (iii) "Landlord's Tax Expenses" with respect to any Tax Year means
                  the aggregate real estate taxes on the Building and Site with
                  respect to that Tax Year, reduced by any abatement receipts
                  with respect to that Tax Year.

            (iv)  "Real estate taxes" means all taxes and special assessments of
                  every kind and nature and user fees and other like fees
                  assessed by any governmental authority on the Building or Site
                  which the Landlord shall become obligated to pay because of or
                  in connection with the ownership, leasing and operation of the
                  Site, the Building and the Property and reasonable expenses of
                  any proceedings for abatement of taxes. The amount of special
                  taxes or special assessments to be included shall be limited
                  to the amount of the installment (plus any interest, other
                  than penalty interest, payable thereon) of such special tax or
                  special assessment required to be paid during the year in
                  respect of which such taxes are being determined. There shall
                  be excluded from such taxes all income, estate, succession,
                  inheritance and transfer taxes; provided, however, that if at
                  any time during the Term the present system of ad valorem
                  taxation of real property shall be changed so that in lieu of
                  the whole or any part of the ad valorem tax on real property
                  there shall be assessed on Landlord a capital levy or other
                  tax on the gross rents received with respect to the Site or
                  Building or Property, or a federal, state, county, municipal,
                  or other local income, franchise, excise or similar tax,
                  assessment, levy or charge distinct from any now in effect in
                  the jurisdiction in which the Property is located) measured by
                  or based, in whole or in part, upon any such gross rents, then
                  any and all of such taxes, assessments, levies or charges, to
                  the extent so measured or based, shall be deemed to be
                  included within the term "real estate taxes" but only to the
                  extent that the same would be payable if the Site and
                  Buildings were the only property of Landlord.

2.8   TENANT ELECTRICITY. If with respect to any calendar year falling within
      the Term or fraction of a calendar year falling within the Term at the
      beginning or end thereof, the cost of furnishing electricity to the
      Premises (including electricity usage for lighting and outlets within the
      Premises and the distribution component of the heating, ventilation and
      air conditioning system serving the Premises) per check meter readings for
      a full calendar year exceeds $1.00 per square foot of Rentable Floor Area
      of the Building, or for any such fraction of a calendar year exceeds the
      corresponding fraction of $1.00 per square foot of Rentable Floor Area of
      the Premises, then Tenant shall pay to Landlord, as Additional Rent, on or
      before the thirtieth (30th) day following receipt by Tenant of the
      statement referred to below in this Section 2.8, the amount of such
      excess. Payments by

                                       21
<PAGE>
      Tenant on account of such excess shall be made monthly at the time and in
      the fashion herein provided for the payment of Annual Fixed Rent. The
      amount so to be paid to Landlord shall be an amount from time to time
      reasonably estimated by Landlord to be sufficient to cover, in the
      aggregate, a sum equal to such excess for each calendar year during the
      Term. If the Landlord shall reasonably determine that the cost of the
      electricity furnished to the Tenant at the Premises exceeds the amount
      being paid under Sections 2.5 and 2.8, then the Landlord may charge the
      Tenant for such excess and the Tenant shall pay the same within thirty
      (30) days of billing therefor.

      Not later than ninety (90) days after the end of the first calendar year
      or fraction thereof ending December 31 and of each succeeding calendar
      year during the Term or fraction thereof at the end of the Term, Landlord
      shall render Tenant a reasonably detailed accounting certified by a
      representative of Landlord showing for the preceding calendar year, or
      fraction thereof, as the case may be, the costs of furnishing electricity
      to the Premises. Said statement to be rendered to Tenant also shall show
      for the preceding year or fraction thereof, as the case may be, the amount
      already paid by Tenant on account of electricity, and the amount remaining
      due from, or overpaid by, Tenant for the year or other period covered by
      the statement.

                                   ARTICLE III

                       CONDITION OF PREMISES; ALTERATIONS

3.1   SUBSTANTIAL COMPLETION.

      (A) Plans and Construction Process.

      (1) Landlord's Work. Attached hereto as Exhibit B are a space plan and
      detailed scope showing the work to be performed by Landlord, at Landlord's
      cost and expense, in order to prepare the Premises for Tenant's occupancy
      (such work being hereinafter referred to as the "Landlord's Work"). For
      the purposes of this Lease, the term "Landlord's Work" shall mean all
      labor, materials and other work necessary for the construction of the
      improvements described in Exhibit B.

      (2) Additional Tenant Work. On or before September 1, 2002 (the "Tenant's
      Submission Date"), Tenant shall deliver to Landlord the data and
      information required by Exhibit B-1 attached hereto for approval by
      Landlord (the "Tenant's Submission"), which approval Landlord shall not
      unreasonably withhold or delay (provided, however, that Landlord's
      determination of matters relating to aesthetic issues relating to
      alterations or changes visible outside the Premises shall be in Landlord's
      sole discretion), showing items of work Tenant desires Landlord to perform
      in addition to the Landlord's Work (such work being hereinafter referred
      to as the "Additional Tenant Work"). For the purposes of this Lease, the
      term "Additional Tenant Work" shall mean all labor, materials and other
      work necessary for the construction of the improvements described in the
      Tenant's Submission. Landlord shall respond to Tenant within three (3)
      business days

                                       22
<PAGE>
      after receipt of Tenant's Submission, either approving such Tenant's
      Submission, requesting additional information in connection therewith or
      disapproving particular items shown thereon.

      (3) Additional Tenant Work Costs. Upon its approval of the Tenant's
      Submission, Landlord shall cause to be prepared a detailed floor plan
      layout together with working drawings (the "Plans") reflecting the
      Landlord's Work and the Additional Tenant Work (such work being
      hereinafter referred to collectively as the "Work"). In connection with
      the foregoing, it is understood and agreed that Landlord shall be
      responsible for the design costs associated with the Landlord's Work and
      Tenant shall be responsible (as part of the Additional Tenant Work Costs,
      as hereinafter defined) for the design costs associated with the
      Additional Tenant Work. On or before October 1, 2002, Landlord shall
      furnish to Tenant (i) a written statement of the costs of the Additional
      Tenant Work (such costs being hereinafter referred to as the "Additional
      Tenant Work Costs"), which such costs shall be paid by Tenant as
      Additional Rent in accordance with Section 3.5 below, and (ii) a list of
      any items of the Additional Tenant Work for which there is a long lead
      time in obtaining the materials therefor or which are specially or
      specifically manufactured, produced or milled for the Additional Tenant
      Work in the Premises and require additional time for receipt or
      installation ("Long Lead Items").

      (4) Authorization to Proceed Date. On or before October 8, 2002 (the
      "Authorization to Proceed Date"), Tenant shall give Landlord written
      authorization to either proceed with the Additional Tenant Work in
      accordance with the approved Tenant's Submission or to proceed with the
      Additional Tenant Work as the same may be modified by Tenant to remove
      particular items of work originally shown on the Tenant's Submission (such
      notice in either event being referred to as the "Notice to Proceed"). In
      addition, Tenant shall, on or before the later to occur of (x) the
      Authorization to Proceed Date or (y) five (5) business days after the
      request therefor, execute and deliver to Landlord any affidavits and
      documentation requested by Landlord in writing required in order to obtain
      all permits and approvals necessary for Landlord to commence and complete
      Landlord's Work on a timely basis ("Permit Documentation").

      (5) Change Orders. Tenant shall have the right, in accordance herewith, to
      submit for Landlord's approval change order requests subsequent to the
      Notice to Proceed, if any (each, a "Change Order Request"). Landlord
      agrees to respond to any such Change Order Request within such time as is
      reasonably necessary (taking into consideration the information contained
      in such Change Order Request) after the submission thereof by Tenant,
      advising Tenant of any anticipated costs ("Change Order Costs") associated
      with such Change Order Request, as well as an estimate of any delay which
      would likely result in the completion of the Work if a Change Order
      Request is made pursuant thereto. Tenant shall have the right to then
      approve or withdraw such Change Order Request within five (5) business
      days after receipt of such information. If Tenant fails to respond within
      such five (5) business day period, such Change Order Request shall be
      deemed withdrawn. If Tenant approves such Change Order Request, then such
      Change Order Request shall be deemed a "Change Order" hereunder and if the
      Change Order is made,

                                       23
<PAGE>
      then the Change Order Costs associated with the Change Order shall be
      deemed additions to the Additional Tenant Work Costs and shall be paid in
      the same manner as Additional Tenant Work Costs are paid as set forth in
      Section 3.5.

      (6) Tenant Response to Requests for Information and Approvals. Except to
      the extent that another time period is expressly herein set forth, Tenant
      shall respond to any written (including e-mail) request from Landlord,
      Landlord's architect, Landlord's contractor and/or Landlord's Construction
      Representative for approvals or information in connection with the Work,
      within three (3) business days of Tenant's receipt of such request.

      (7) Time of the Essence. Time is of the essence in connection with the
      obligations of Landlord and Tenant under this Section 3.1.

      (B) Tenant Delay.

      (1) A "Tenant Delay" shall be defined as the following:

         (a) Tenant's failure to submit the Tenant's Submission on or before the
         Tenant's Submission Date, to give authorization to Landlord to proceed
         with the Additional Tenant Work on or before the Authorization to
         Proceed Date or to provide all required Permit Documentation to
         Landlord on or before the Authorization to Proceed Date (assuming in
         any event that such failure is not the direct result of Landlord's
         failure to timely give any notice required in this Section 3.1); or

         (b) Tenant's failure timely to respond to any request from Landlord,
         Landlord's architect, Landlord's contractor and/or Landlord's
         Construction Representative including, without limitation, within the
         time periods set forth in Section 3.1(A)(6) above;

         (c) Tenant's failure to pay the Additional Tenant Work Costs in
         accordance with Section 3.5;

         (d) Any delay due to Long Lead Items;

         (e) Any delay due to changes, alterations or additions required or made
         by Tenant after giving Landlord the Notice to Proceed, including,
         without limitation, Change Orders; or

         (f) Any other delays caused by Tenant, Tenant's contractors, or anyone
         else engaged by Tenant in connection with the preparation of the
         Premises for Tenant's occupancy, including, without limitation, utility
         companies and other entities furnishing communications, data processing
         or other service, equipment, or furniture.

                                       24
<PAGE>
      (2) Tenant Obligations with Respect to Tenant Delays.

         (a) Tenant covenants that no Tenant Delay shall delay commencement of
         the Term or the obligation to pay Annual Fixed Rent or Additional Rent,
         regardless of the reason for such Tenant Delay or whether or not it is
         within the control of Tenant, unless such Tenant Delay is the direct
         result of Landlord's failure to give any notice required by Landlord to
         be given under this Section 3.1. The Work shall be deemed substantially
         completed as of the date when the Work would have been substantially
         completed but for any Tenant Delays, as determined by Landlord's
         architect in the exercise of its good faith business judgment.

         (b) Tenant shall reimburse Landlord the amount, if any, by which the
         cost of the Work is increased as the result of any Tenant Delay, as
         reasonably evidenced by Landlord.

         (c) Any amounts due from Tenant to Landlord under this Section
         3.1(B)(2) shall be due and payable within thirty (30) days of billing
         therefor, and shall be considered to be Additional Rent. Nothing
         contained in this Section 3.1(B)(2) shall limit or qualify or prejudice
         any other covenants, agreements, terms, provisions and conditions
         contained in this Lease.

      (C) Substantial Completion of Landlord's Work.

      (1) Landlord's Obligations. Subject to Tenant Delays and delays due to
      governmental regulation, unusual scarcity of or inability to obtain labor
      or materials, labor difficulties, casualty, or other events reasonably
      beyond Landlord's control (collectively, "Force Majeure"), Landlord shall
      use reasonable speed and diligence to have the Work substantially
      completed on or before the Estimated Commencement Date, but Tenant shall
      have no claim against Landlord for failure so to complete construction in
      the Premises, except as set forth in Section 3.2 below.

      (2) Definition of Substantial Completion. The Premises shall be treated as
      having been substantially completed on the later of:

         (a) The date on which the Work, together with common facilities for
         access and services to the Premises, has been completed (or would have
         been completed except for Tenant Delays) except for minor items of work
         and adjustment of equipment and fixtures which can be completed after
         occupancy has been taken without causing substantial interference with
         Tenant's use of the Premises (i.e. so-called "punch list" items), or

         (b) The date when permission has been obtained from the applicable
         governmental authority, to the extent required by law, for occupancy by
         Tenant of the Premises for the Permitted Use (or would have been
         obtained but for Tenant Delays).

                                       25
<PAGE>
      In the event of any dispute as to the date on which the Work has been
      substantially completed, the reasonable determination of Landlord's
      architect as to such date shall be deemed conclusive and binding on both
      Landlord and Tenant.

      (3) Incomplete Work. Landlord shall complete as soon as conditions
      practically permit any incomplete items of Work, and Tenant shall
      cooperate with Landlord in providing access as may be required to complete
      such work in a normal manner. Landlord shall use reasonable efforts to
      minimize disruption to Tenant's business during Landlord's completion of
      such work to the extent reasonably practicable under the circumstances.

      (4) Early Access by Tenant. Landlord shall permit Tenant access for
      installing Tenant's trade fixtures and computer, telephone and other
      communications equipment, furniture, systems and wiring in portions of the
      Premises no later than fourteen (14) days prior to substantial completion
      when it can be done without material interference with remaining work or
      with the maintenance of harmonious labor relations. Any such access by
      Tenant shall be at upon all of the terms and conditions of the Lease
      (other than the payment of Annual Fixed Rent, Operating Expenses Allocable
      to the Premises and Landlord's Tax Expenses Allocable to the Premises and
      tenant electricity) and shall be at Tenant's sole risk, and Landlord shall
      not be responsible for any injury to persons or damage to property
      resulting from such early access by Tenant (except to the extent caused by
      the negligence or willful misconduct of Landlord or its agents, employees
      or contractors).

      (5) Prohibition on Access by Tenant Prior to Actual Substantial
      Completion. If, prior to the date that the Premises are in fact actually
      substantially complete, the Premises are deemed to be substantially
      complete pursuant to the provisions of this Section 3.1 (i.e. and the
      Commencement Date has therefore occurred), Tenant shall not (except with
      Landlord's consent, which consent shall not be unreasonably withheld,
      conditioned or delayed) be entitled to take possession of the Premises for
      the Permitted Use until the Premises are in fact actually substantially
      complete.

3.2   CERTAIN TENANT RIGHTS. (A) If Landlord shall have failed substantially to
      complete the Work in the Premises described in the Plans on or before
      April 1, 2003 (which date shall be extended automatically for such periods
      of time as Landlord is prevented from proceeding with or completing the
      same by reason of Tenant Delays), Landlord shall pay to Tenant or grant
      Tenant free rent (at Landlord's election) in an amount equal to the sum of
      (I) Seventy Thousand Two Hundred Seventy-Three and 00/100 Dollars
      ($70,273.00) per month (prorated as appropriate to the extent that Tenant
      is only required to pay holdover costs for a partial month) (the "Holdover
      Compensation"), being equal to the difference between (x) the monthly
      holdover costs chargeable by the sublandlord and payable by Tenant under
      that certain Agreement of Sublease dated March 31, 2000 (the "52 Second
      Avenue Sublease") by and between


                                       26
<PAGE>
      Renaissance Worldwide, Inc., as sublandlord, and Tenant, as subtenant,
      with respect to premises located at 52 Second Avenue, Waltham,
      Massachusetts (the "52 Second Avenue Premises") during any period of time
      in which Tenant remains in occupancy of the 52 Second Avenue Premises
      beyond the expiration date of the 52 Second Avenue Sublease (as set forth
      in the next paragraph of this subsection (A)) and (y) the monthly amount
      that Tenant otherwise have been required to pay for the 52 Second Avenue
      Premises in accordance with the terms and provisions of the 52 Second
      Avenue Sublease in the absence of any holdover penalties, plus (II) the
      costs (if any) actually incurred by Tenant under Section 17 of the 52
      Second Avenue Sublease as the direct result of Landlord's failure to
      substantially complete the Work by April 1, 2003, as such date may be
      extended as the result of Tenant Delays (it being understood and agreed
      that in no event shall Landlord be liable for any costs pursuant to this
      subsection (II) in excess of Seventy Thousand Two Hundred Seventy-Three
      and 00/100 Dollars ($70,273.00) in the aggregate). In that regard, it is
      understood and agreed that Landlord shall under no circumstances be
      required to pay any Holdover Compensation if the Work is substantially
      completed on or before April 1, 2003 or if no holdover penalties are
      actually imposed by the sublandlord under the 52 Second Avenue Sublease.

      In connection with the foregoing, Tenant represents and warrants that (i)
      there are no amendments to the 52 Second Avenue Sublease other than those
      listed in the immediately preceding paragraph (if any) and (ii) the term
      of the 52 Second Avenue Sublease is scheduled to expire on March 31, 2003.
      Tenant further covenants and agrees that it will not amend the 52 Second
      Avenue Sublease or otherwise take any action thereunder that would
      increase the amount of holdover costs to be paid by Tenant under the 52
      Second Avenue Sublease following the expiration of the term thereof
      without the prior written consent of Landlord (provided that in any event,
      if the holdover costs are increased without Landlord's consent, Landlord
      shall have no liability or responsibility therefor and such increase shall
      not be deemed to be a part of the Holdover Compensation otherwise payable
      hereunder). In addition, notwithstanding anything contained in this
      subsection (A) to the contrary, it is understood and agreed that (i)
      Landlord shall have no liability or responsibility to pay any holdover
      costs incurred by Tenant attributable to any reason other than the failure
      of Landlord to substantially complete the Work by April 1, 2003 and (ii)
      such right to receive Holdover Compensation shall be Tenant's sole and
      exclusive remedy for Landlord's failure to substantially complete the Work
      within such time.

      (B) If Landlord shall have failed substantially to complete the Work in
      the Premises described in the Plans on or before the Outside Completion
      Date as defined in Section 1.1 hereof (which date shall be extended
      automatically (i) for such periods of time as Landlord is prevented from
      proceeding with or completing the same by reason of Tenant Delays or (ii)
      for up to two hundred forty (240) days in the event of any Force Majeure
      as defined in Section 3.1) Tenant shall have the right to terminate this
      Lease by giving notice to Landlord of Tenant's desire to do so before such
      completion and within the time period from the Outside Completion Date (as
      so extended) until the date which is thirty (30) days subsequent to the
      Outside Completion Date (as so extended); and, upon the giving of such
      notice, the term of this Lease shall cease and come to an end without
      further


                                       27
<PAGE>
      liability or obligation on the part of either party unless, within thirty
      (30) days after receipt of such notice, Landlord substantially completes
      the Work; and such right of termination shall be Tenant's sole and
      exclusive remedy for Landlord's failure so to complete the Work within
      such time. Each day of Tenant Delay shall be deemed conclusively to cause
      an equivalent day of delay by Landlord in substantially completing the
      Work pursuant to Section 3.1, and thereby automatically extend for each
      such equivalent day of delay the date of the Outside Completion Date.

3.3   GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION. All construction work
      required or permitted by this Lease shall be done in a good and
      workmanlike manner and in compliance with all applicable laws, ordinances,
      rules, regulations, statutes, by-laws, court decisions, and orders and
      requirements of all public authorities ("Legal Requirements") and all
      requirements of insurers of the Building ("Insurance Requirements"). All
      of Tenant's work shall be coordinated with any work being performed by or
      for Landlord and in such manner as to maintain harmonious labor relations.
      Each party may inspect the work of the other at reasonable times and shall
      promptly give notice of observed defects. Each party authorizes the other
      to rely in connection with design and construction upon approval and other
      actions on the party's behalf by any Construction Representative of the
      party named in Section 1.1 or any person hereafter designated in
      substitution or addition by notice to the party relying. Except as
      otherwise provided in Article IV, the work required of Landlord pursuant
      to this Article III shall be deemed approved by Tenant when Tenant
      commences occupancy of the Premises for the Permitted Uses, except for (i)
      items which are uncompleted (including punch list items and long lead
      items) at the time Tenant commences occupancy, (ii) items as to which
      Tenant shall have given notice to Landlord within thirty (30) days of the
      Commencement Date and (iii) items which could not readily have been
      discovered in the exercise of reasonable diligence within the thirty (30)
      day period set forth in subsection (ii) above and as to which Tenant shall
      have given notice no later than twelve (12) months after the date
      Landlord's Work is deemed substantially complete in accordance with
      Section 3.1 above.

3.4   INTENTIONALLY OMITTED.

3.5   ADDITIONAL TENANT WORK COSTS. To the extent, if any, that there are
      Additional Tenant Work Costs, Tenant shall pay Landlord, as Additional
      Rent, 100% of the Additional Tenant Work Costs at the time the Notice to
      Proceed is given (or in the case of a Change Order, at the time of
      Tenant's approval of the Change Order Request).

3.6   ALTERATIONS. Tenant shall not make alterations and additions to Tenant's
      space except in accordance with plans and specifications therefor first
      approved by Landlord, which approval shall not be unreasonably withheld or
      delayed (provided, however, that Tenant shall have the right to make
      decorative changes such as repainting or recarpeting the Premises at a
      cost not to exceed $50,000 during any twelve (12) month period during the
      Lease Term without Landlord's consent, so long as the other conditions set
      forth in this Section 3.6 have been satisfied). However, Landlord's
      determination of matters


                                       28
<PAGE>
      relating to aesthetic issues relating to alterations, additions or
      improvements which are visible outside the Premises shall be in Landlord's
      sole discretion. Without limiting such standard Landlord shall not be
      deemed unreasonable for withholding approval of any alterations or
      additions (including, without limitation, any alterations or additions to
      be performed by Tenant under Section 3.1) which (a) in Landlord's opinion
      might adversely affect any structural or exterior element of the Building,
      any area or element outside of the Premises, or any facility serving any
      area of the Building outside of the Premises, or (b) involve or affect the
      exterior design, size, height, or other exterior dimensions of the
      Building or (c) will require unusual expense to readapt the Premises to
      normal office use on Lease termination or expiration or increase the cost
      of construction or of insurance or taxes on the Building or of the
      services called for by Section 4.1 unless Tenant first gives assurance
      acceptable to Landlord for payment of such increased cost and that such
      readaptation will be made prior to such termination or expiration without
      expense to Landlord, or (d) enlarge the Rentable Floor Area of the
      Premises. Landlord's review and approval of any such plans and
      specifications and consent to perform work described therein shall not be
      deemed an agreement by Landlord that such plans, specifications and work
      conform with applicable Legal Requirements and Insurance Requirements nor
      deemed a waiver of Tenant's obligations under this Lease with respect to
      applicable Legal Requirements and Insurance Requirements nor impose any
      liability or obligation upon Landlord with respect to the completeness,
      design sufficiency or compliance of such plans, specifications and work
      with applicable Legal Requirements and Insurance Requirements. All
      alterations and additions shall be part of the Building unless and until
      Landlord shall specify the same for removal pursuant to Section 5.2. All
      of Tenant's alterations and additions and installation of furnishings
      shall be coordinated with any work being performed by Landlord and in such
      manner as to maintain harmonious labor relations and not to damage the
      Building or Site or unreasonably interfere with construction or operation
      of the Building and other improvements to the Site and, except for
      installation of furnishings, shall be performed by Landlord's general
      contractor or by contractors or workmen first approved by Landlord. Except
      for work by Landlord's general contractor, Tenant, before its work is
      started, shall secure all licenses and permits necessary therefor; deliver
      to Landlord a statement of the names of all its contractors and
      subcontractors and the estimated cost of all labor and material to be
      furnished by them and security satisfactory to Landlord protecting
      Landlord against liens arising out of the furnishing of such labor and
      material; and cause each contractor to carry workmen's compensation
      insurance in statutory amounts covering all the contractor's and
      subcontractor's employees and commercial general liability insurance or
      comprehensive general liability insurance with a broad form comprehensive
      liability endorsement with such limits as Landlord may reasonably require,
      but in no event less than $2,000,000.00 combined single limit per
      occurrence on a per location basis (all such insurance to be written in
      companies reasonably approved by Landlord and naming and insuring Landlord
      and Landlord's managing agent as additional insureds and insuring Tenant
      as well as the contractors), and to deliver to Landlord certificates of
      all such insurance. Tenant agrees to pay promptly when due the entire cost
      of any work done on the Premises by Tenant, its agents, employees, or
      independent contractors, and not to cause or permit any liens for labor or
      materials performed or furnished in connection therewith to attach



                                       29
<PAGE>
      to the Premises or the Buildings or the Site and immediately to discharge
      any such liens which may so attach. Tenant shall pay, as Additional Rent,
      100% of any real estate taxes on the Complex which shall, at any time
      after commencement of the Term, directly and specifically result from any
      alteration, addition or improvement to the Premises made by Tenant.

                                   ARTICLE IV

                 LANDLORD'S COVENANTS; INTERRUPTIONS AND DELAYS

4.1   LANDLORD COVENANTS:


      4.1.1 SERVICES FURNISHED BY LANDLORD. To furnish services, utilities,
      facilities and supplies set forth in Exhibit C equal to those customarily
      provided by landlords in high quality buildings in the Boston West
      Suburban Market subject to escalation reimbursement in accordance with
      Section 2.6.

      4.1.2 ADDITIONAL SERVICES AVAILABLE TO TENANT. To furnish, at Tenant's
      expense, reasonable additional Building operation services which are usual
      and customary in similar office buildings in the Boston West Suburban
      Market upon reasonable advance request of Tenant at reasonable and
      equitable rates from time to time established by Landlord. Tenant agrees
      to pay to Landlord, as Additional Rent, the cost of any such additional
      Building services requested by Tenant and for the cost of any additions,
      alterations, improvements or other work performed by Landlord in the
      Premises at the request of Tenant within thirty (30) days after being
      billed therefor.

      4.1.3 ROOF, EXTERIOR WALL, FLOOR SLAB AND COMMON FACILITY REPAIRS. Except
      for (a) normal and reasonable wear and use and (b) damage caused by fire
      and casualty and by eminent domain, and except as otherwise provided in
      Article VI and subject to the escalation provisions of Section 2.6, (i) to
      make such repairs to and replacements of the roof, exterior walls, floor
      slabs and common areas, building systems (including heating, ventilation
      and air conditioning, electrical, water and sewer) and facilities as may
      be necessary to keep them in good and serviceable condition and (ii) to
      maintain the Building (exclusive of Tenant's responsibilities under this
      Lease) in a first class manner comparable to the maintenance of similar
      properties in the Boston West Suburban Market.

      4.1.4 SIGNAGE. (A) To provide and install, at Landlord's expense, letters
      to identify Tenant's official name (i) in the existing building standard
      directory located at the ground floor entrances to the Building, (ii) on
      the existing monument sign at the intersection of Route 117 and Jones
      Road, (iii) on the existing monument type directional sign at the entrance
      to the drop-off area for the Building and (iv) in the existing brush
      stainless steel signage system in the main lobby on the ground floor of
      the Building.


                                       30
<PAGE>
      (B) All signage described herein shall be in the building standard
      graphics and no others shall be used or permitted.

      (C) Tenant's rights set forth herein shall be available only so long as
      this Lease is in full force and effect and there shall not exist any Event
      of Default, and shall not be available and shall cease at such time as
      Netegrity, Inc. shall cease to be the Tenant hereunder (provided, however,
      that such signage rights shall be transferable in the event of an
      assignment or subleasing pursuant to Section 5.6.1 below, so long as
      Tenant pays all costs associated with resigning).

      (D) Tenant's rights as set forth herein shall be in common with signage
      rights granted from time to time by Landlord or the owner of the Site or
      portions thereof to other tenants of the Building or the Site.

4.2   INTERRUPTIONS AND DELAYS IN SERVICES AND REPAIRS, ETC. Landlord shall not
      be liable to Tenant for any compensation or reduction of rent by reason of
      inconvenience or annoyance or for loss of business arising from the
      necessity of Landlord or its agents entering the Premises in the manner
      set forth in this Lease for any of the purposes in this Lease authorized,
      or for repairing the Premises or any portion of the Building however the
      necessity may occur. In case Landlord is prevented or delayed from making
      any repairs, alterations or improvements, or furnishing any services or
      performing any other covenant or duty to be performed on Landlord's part,
      by reason of any cause reasonably beyond Landlord's control, including
      without limitation the causes set forth in Section 3.2 hereof as being
      reasonably beyond Landlord's control, Landlord shall not be liable to
      Tenant therefor, nor, except as expressly otherwise provided below or in
      Article VI, shall Tenant be entitled to any abatement or reduction of rent
      by reason thereof. Notwithstanding the foregoing, in the event that the
      electrical, heating, ventilating, air conditioning, or all elevator
      service to the Premises shall be shut down for more than five (5) full and
      consecutive business days, then, Tenant shall be entitled to an equitable
      abatement of Annual Fixed Rent in an amount proportionate to the nature
      and extent of the interruption of Tenant's usage of the Premises as a
      result of the loss of service (taking into account any recovery Tenant may
      receive under any insurance policy providing coverage for business
      interruption). Notwithstanding anything herein contained to the contrary,
      in no event shall any of the events referred to in this Section give rise
      to a claim in Tenant's favor that such failure constitutes actual or
      constructive, total or partial, eviction from the Premises.

      Landlord reserves the right to stop any service or utility system, when
      necessary by reason of accident or emergency, or until necessary repairs
      have been completed; provided, however, that in each instance of stoppage,
      Landlord shall exercise reasonable diligence to eliminate the cause
      thereof. Except in case of emergency repairs, Landlord will give Tenant
      reasonable advance notice of any contemplated stoppage and will use
      reasonable efforts to avoid unnecessary inconvenience to Tenant by reason
      thereof.

4.3   LANDLORD INSURANCE. Landlord shall carry at all times during the Term of
      this


                                       31
<PAGE>
      Lease (i) commercial general liability insurance with respect to the
      Building in an amount not less than $5,000,000.00 combined single limit
      per occurrence and (ii) insurance against loss or damage with respect to
      the Building covered by the so-called "all risk" type insurance coverage
      in an amount equal to at least the replacement value of the Building.
      Landlord may also maintain such other insurance as may from time to time
      be required by a mortgagee holding a mortgage lien on the Building.
      Further, Landlord may also maintain such insurance against loss of annual
      fixed rent and additional rent and such other risks and perils as Landlord
      deems proper. Any and all such insurance (i) may be maintained under a
      blanket policy affecting other properties of Landlord and/or its
      affiliated business organizations, (ii) may be written with deductibles as
      determined by Landlord and (iii) shall be subject to escalation
      reimbursement in accordance with Section 2.6.

4.4   ADA COMPLIANCE. As of the date hereof, Landlord represents and warrants
      that Landlord has not received notice from any governmental agencies that
      the Building is in violation of Title III of the Americans with
      Disabilities Act.

                                    ARTICLE V

                               TENANT'S COVENANTS

      Tenant covenants during the term and such further time as Tenant occupies
      any part of the Premises:

5.1   PAYMENTS. To pay when due all fixed rent and Additional Rent and all
      charges for utility services rendered to the Premises (except as otherwise
      provided in Exhibit C) and, as further Additional Rent, all charges for
      additional services rendered pursuant to Section 4.1.2.

5.2   REPAIR AND YIELD UP. Except as otherwise provided in Article VI and
      Section 4.1.3 to keep the Premises in good order, repair and condition,
      reasonable wear and tear and damage caused by casualty or eminent domain
      only excepted, and all glass in windows (except glass in exterior walls
      unless the damage thereto is attributable to Tenant's negligence or
      misuse) and doors of the Premises whole and in good condition with glass
      of the same type and quality as that injured or broken, damage by fire or
      taking under the power of eminent domain only excepted, and at the
      expiration or termination of this Lease peaceably to yield up the Premises
      all construction, work, improvements, and all alterations and additions
      thereto in good order, repair and condition, reasonable wear and tear and
      damage caused by casualty or eminent domain only excepted, first removing
      (i) all goods and effects of Tenant, (ii) to the extent specified by
      Landlord by notice to Tenant given at least ten (10) days before such
      expiration or termination, the wiring for Tenant's computer, telephone and
      other communication systems and equipment and (iii) to the extent
      specified by Landlord at the time approval of the same is given, all
      alterations and additions made by Tenant and all partitions, and in any
      event repairing any


                                       32
<PAGE>
      damage caused by such removal and restoring the Premises and leaving them
      clean and neat. Tenant shall not permit or commit any waste, and Tenant
      shall be responsible for the cost of repairs which may be made necessary
      by reason of damage to common areas in the Building, to the Site or to the
      other building caused by Tenant, Tenant's agents, contractors, employees,
      sublessees, licensees, concessionaires or invitees.

5.3   USE. To use and occupy the Premises for the Permitted Use only, and not to
      injure or deface the Premises, Building, the Site or any other part of the
      Complex nor to permit in the Premises or on the Site any auction sale,
      vending machine (unless consented to by Landlord, which consent shall not
      be unreasonably withheld or delayed), or inflammable fluids or chemicals,
      or nuisance, or the emission from the Premises of any objectionable noise
      or odor, and not to use or devote the Premises or any part thereof for any
      purpose other than the Permitted Uses, nor any use thereof which is
      inconsistent with the maintenance of the Building as an office building of
      the first class in the quality of its maintenance, use and occupancy, or
      which is contrary to law or ordinance or liable to invalidate or increase
      the premiums for any insurance on the Building or its contents or liable
      to render necessary any alteration or addition to the Building that would
      not have been rendered necessary but for such use by Tenant. Further, (i)
      Tenant shall not, nor shall Tenant permit its employees, invitees, agents,
      independent contractors, contractors, assignees or subtenants to, keep,
      maintain, store or dispose of (into the sewage or waste disposal system or
      otherwise) or engage in any activity which might produce or generate any
      substance which is or may hereafter be classified as a hazardous material,
      waste or substance (collectively "Hazardous Materials"), under federal,
      state or local laws, rules and regulations, including, without limitation,
      42 U.S.C. Section 6901 et seq., 42 U.S.C. Section 9601 et seq., 42 U.S.C.
      Section 2601 et seq., 49 U.S.C. Section 1802 et seq. and Massachusetts
      General Laws, Chapter 21E and the rules and regulations promulgated under
      any of the foregoing, as such laws, rules and regulations may be amended
      from time to time (collectively "Hazardous Materials Laws"), (ii) Tenant
      shall immediately notify Landlord of any incident in, on or about the
      Premises, the Building or the Site that would require the filing of a
      notice under any Hazardous Materials Laws, (iii) Tenant shall comply and
      shall cause its employees, invitees, agents, independent contractors,
      contractors, assignees and subtenants to comply with each of the foregoing
      and (iv) Landlord shall have the right to make such inspections (including
      testing) as Landlord shall elect from time to time to determine that
      Tenant is complying with the foregoing.

      Notwithstanding the foregoing, Tenant may use normal amounts and types of
      substances typically used for office uses, provided that Tenant uses such
      substances in the manner in which they are normally used, and in
      compliance with all Hazardous Materials Laws and other Legal Requirements.

5.4   OBSTRUCTIONS; ITEMS VISIBLE FROM EXTERIOR; RULES AND REGULATIONS. Not to
      obstruct in any manner any portion of the Building not hereby leased or
      any portion thereof or of the Site used by Tenant in common with others;
      not without prior consent of Landlord to permit the painting or placing of
      any signs, curtains, blinds, shades, awnings, aerials or flagpoles, or the
      like, visible from outside the


                                       33
<PAGE>
      Premises; and to comply with all reasonable Rules and Regulations of
      general applicability now or hereafter made by Landlord, of which Tenant
      has been given notice, for the care and use of the Building and Site and
      their facilities and approaches; Landlord shall not be liable to Tenant
      for the failure of other occupants of the Buildings to conform to such
      Rules and Regulations.

5.5   SAFETY APPLIANCES. To keep the Premises equipped with all safety
      appliances required by any public authority because of any use made by
      Tenant other than normal office use, and to procure all licenses and
      permits so required because of such use and, if requested by Landlord, to
      do any work so required because of such use, it being understood that the
      foregoing provisions shall not be construed to broaden in any way Tenant's
      Permitted Use.

5.6   ASSIGNMENT; SUBLEASE. Except as otherwise expressly provided herein,
      Tenant covenants and agrees that it shall not assign, mortgage, pledge,
      hypothecate or otherwise transfer this Lease and/or Tenant's interest in
      this Lease or sublet (which term, without limitation, shall include
      granting of concessions, licenses or the like) the whole or any part of
      the Premises. Any assignment, mortgage, pledge, hypothecation, transfer or
      subletting not expressly permitted in or consented to by Landlord under
      Sections 5.6.1-5.6.5 shall be void, ab initio; shall be of no force and
      effect; and shall confer no rights on or in favor of third parties. In
      addition, Landlord shall be entitled to seek specific performance of or
      other equitable relief with respect to the provisions hereof.

5.6.1 Notwithstanding the foregoing provisions of Section 5.6 above and the
      provisions of Sections 5.6.2 and 5.6.4 below, but subject to the
      provisions of Sections 5.6.3 and 5.6.5, below Tenant shall have the right
      to assign this Lease or to sublet the Premises (in whole or in part) to
      (i) any parent or subsidiary corporation of Tenant, (ii) any corporation
      into which Tenant may be converted or with which it may merge or (iii) any
      entity which acquires all or substantially all of the stock or assets of
      Tenant, provided that in the event of any of the foregoing the entity to
      which this Lease is so assigned or which so sublets the Premises has a
      credit worthiness (e.g. assets on a pro forma basis using generally
      accepted accounting principles consistently applied and using the most
      recent financial statements) which is the same or better than the Tenant
      as of the date of this Lease. In the event of an assignment or subletting
      pursuant to subsection (i) above, if any parent or subsidiary corporation
      of Tenant to which this Lease is assigned or the Premises sublet (in whole
      or in part) shall cease to be such a parent or subsidiary corporation,
      such cessation shall be considered a new assignment or subletting subject
      to the applicable provisions of Sections 5.6 through 5.6.5 as appropriate.

5.6.1.1 Notwithstanding the provisions of Section 5.6 above, in the event Tenant
      desires (i) to assign this Lease or (ii) to sublet fifty percent (50%) or
      more of the Rentable Floor Area of the Premises for all or substantially
      all of the then-remaining Term of this Lease, Tenant shall notify Landlord
      thereof in writing and Landlord shall have the right at its sole option,
      to be exercised within twenty (20) days after receipt of Tenant's notice,
      to terminate this Lease as of the effective date of the proposed
      assignment or subletting (as


                                       34
<PAGE>
      set forth in Tenant's notice); provided, however, that upon the
      termination date, all obligations relating to the period after such
      termination date (but not those relating to the period before such
      termination date) shall cease and promptly upon being billed therefor by
      Landlord, Tenant shall make final payment of all Annual Fixed Rent and
      Additional Rent due from Tenant through the termination date.
      Notwithstanding the foregoing, in the event that Tenant shall only propose
      to sublease a portion of the Premises, Landlord shall only have the right
      to so terminate this Lease with respect to the portion of the Premises
      which Tenant proposes to sublease (the "Terminated Portion of the
      Premises") and from and after the termination date the Rentable Floor Area
      of the Premises shall be reduced to the rentable floor area of the
      remainder of the Premises and the definition of Rentable Floor Area of the
      Premises shall be so amended and after such termination all references in
      this Lease to the "Premises" or the "Rentable Floor Area of the Premises"
      shall be deemed to be references to the remainder of the Premises and
      accordingly Tenant's payments for Annual Fixed Rent, operating costs, real
      estate taxes and electricity shall be reduced on a pro rata basis to
      reflect the size of the remainder of the Premises.

      In the event that Landlord shall not exercise its termination rights as
      aforesaid, or shall fail to give any or timely notice pursuant to this
      Section, the provisions of Sections 5.6.2-5.6.5 shall be applicable. This
      Section 5.6.1.1 shall not be applicable to an assignment or sublease
      pursuant to Section 5.6.1.

5.6.2 Notwithstanding the provisions of Section 5.6 above, but subject to the
      provisions of this Section 5.6.2 and the provisions of Sections 5.6.3,
      5.6.4 and 5.6.5 below, in the event that Landlord shall not have exercised
      the termination right as set forth in Section 5.6.1.1, or shall have
      failed to give any or timely notice under Section 5.6.1.1, then for a
      period of one hundred twenty (120) days (i) after the receipt of
      Landlord's notice stating that Landlord does not elect the termination
      right, or (ii) after the expiration of the twenty (20) day period referred
      to in Section 5.6.1.1, in the event Landlord shall not give any or timely
      notice under Section 5.6.1.1 as the case may be, Tenant shall have the
      right to assign this Lease or sublet the Premises in accordance with
      Tenant's notice to Landlord given as provided in Section 5.6.3 provided
      that, in each instance, Tenant first obtains the express prior written
      consent of Landlord, which consent shall not be unreasonably withheld or
      delayed. Without limiting the foregoing standard, Landlord shall not be
      deemed to be unreasonably withholding its consent to such a proposed
      assignment or subleasing if:

            (a)   the proposed assignee or subtenant is in active negotiation
                  with Landlord for premises in the Building (and adequate space
                  is available for such tenant in the Building) or is not of a
                  character consistent with the operation of a first class
                  office building (by way of example Landlord shall not be
                  deemed to be unreasonably withholding its consent to an
                  assignment or subleasing to any governmental or
                  quasi-governmental agency), or

            (b)   the proposed assignee or subtenant is not of good character
                  and reputation, or


                                       35
<PAGE>
            (c)   the proposed assignee or subtenant does not possess adequate
                  financial capability to perform the Tenant obligations as and
                  when due or required, or

            (d)   the assignee or subtenant proposes to use the Premises (or
                  part thereof) for a purpose other than the purpose for which
                  the Premises may be used as stated in Section 1.1 hereof, or

            (e)   the character of the business to be conducted or the proposed
                  use of the Premises by the proposed subtenant or assignee
                  shall (i) be likely to increase Landlord's Operating Expenses
                  beyond that which Landlord now incurs for use by Tenant; (ii)
                  be likely to increase the burden on elevators or other
                  Building systems or equipment over the burden permitted in
                  this Lease; or (iii) violate or be likely to violate any
                  provisions or restrictions contained herein relating to the
                  use or occupancy of the Premises, or

            (f)   there shall be existing an Event of Default (defined in
                  Section 7.1), or

            (g)   any part of the rent payable under the proposed assignment or
                  sublease shall be based in whole or in part on the income or
                  profits derived from the Premises or if any proposed
                  assignment or sublease shall potentially have any adverse
                  effect on the real estate investment trust qualification
                  requirements applicable to Landlord and its affiliates.

5.6.3 Tenant shall give Landlord notice of any proposed sublease or assignment,
      and said notice shall specify the provisions of the proposed assignment or
      subletting, including (a) the name and address of the proposed assignee or
      subtenant, (b) in the case of a proposed assignment or subletting pursuant
      to Section 5.6.2, such information as to the proposed assignee's or
      proposed subtenant's net worth and financial capability and standing as
      may reasonably be required for Landlord to make the determination referred
      to in Section 5.6.2 above (provided, however, that Landlord shall hold
      such information confidential having the right to release same to its
      officers, accountants, attorneys and mortgage lenders on a confidential
      basis), (c) all of the material terms and provisions upon which the
      proposed assignment or subletting is to be made, (d) in the case of a
      proposed assignment or subletting pursuant to Section 5.6.2, all other
      information necessary to make the determination referred to in Section
      5.6.2 above and (e) in the case of a proposed assignment or subletting
      pursuant to Section 5.6.1 above, such information as may be reasonably
      required by Landlord to determine that such proposed assignment or
      subletting complies with the requirements of said Section 5.6.1.

      Landlord shall respond to Tenant's request for consent within fifteen (15)
      days after receipt thereof, either approving the proposed assignment or
      sublease, rejecting the same or requesting additional information; it
      being understood and agreed that Landlord's failure to timely respond
      shall be deemed to be an approval of the proposed assignment or


                                       36
<PAGE>
      sublease. If Landlord shall consent to the proposed assignment or
      subletting, as the case may be, then, in such event, Tenant may thereafter
      sublease or assign pursuant to Tenant's notice, as given hereunder;
      provided, however, that if such assignment or sublease shall not be
      executed and delivered to Landlord within one hundred twenty (120) days
      after the date of Landlord's consent, the consent shall be deemed null and
      void and the provisions of Section 5.6.1.1 shall be applicable.

5.6.4 In addition, in the case of any assignment or subleasing as to which
      Landlord may consent (other than an assignment or subletting permitted
      under Section 5.6.1 hereof) such consent shall be upon the express and
      further condition, covenant and agreement, and Tenant hereby covenants and
      agrees that, in addition to the Annual Fixed Rent, Additional Rent and
      other charges to be paid pursuant to this Lease, fifty percent (50%) of
      the "Assignment/Sublease Profits" (hereinafter defined), if any, shall be
      paid to Landlord. The "Assignment/Sublease Profits" shall be the excess,
      if any, of (a) the "Assignment/Sublease Net Revenues" as hereinafter
      defined over (b) the Annual Fixed Rent and Additional Rent and other
      charges provided in this Lease (provided, however, that for the purpose of
      calculating the Assignment/Sublease Profits in the case of a sublease,
      appropriate proportions in the applicable Annual Fixed Rent, Additional
      Rent and other charges under this Lease shall be made based on the
      percentage of the Premises subleased and on the terms of the sublease).
      The "Assignment/Sublease Net Revenues" shall be the fixed rent, additional
      rent and all other charges and sums payable either initially or over the
      term of the sublease or assignment plus all other profits and increases to
      be derived by Tenant as a result of such subletting or assignment, less
      the actual costs of Tenant incurred in such subleasing or assignment (the
      definition of which shall include but not necessarily be limited to rent
      concessions, brokerage commissions, alteration allowances and reasonable
      attorneys fees), as set forth in a statement certified by an appropriate
      officer of Tenant and delivered to Landlord within sixty (60) days of the
      full execution of the sublease or assignment document.

      All payments of the Assignment/Sublease Profits due Landlord shall be made
      within ten (10) days of receipt of same by Tenant.

5.6.5 (A) It shall be a condition of the validity of any assignment or
          subletting of right under Section 5.6.1 above, or consented to under
          Section 5.6.2 above, that both Tenant and the assignee or sublessee
          enter into a separate written instrument directly with Landlord in a
          form and containing terms and provisions reasonably required by
          Landlord, including, without limitation, the agreement of the assignee
          or sublessee to be bound directly to Landlord for all the obligations
          of the Tenant hereunder, including, without limitation, the obligation
          (a) to pay the rent and other amounts provided for under this Lease
          (but in the case of a partial subletting pursuant to Section 5.6.1,
          such subtenant shall agree on a pro rata basis to be so bound) and (b)
          to comply with the provisions of Sections 5.6 through 5.6.5 hereof.
          Such assignment or subletting shall not relieve the Tenant named
          herein of any of the obligations of the Tenant hereunder and Tenant
          shall remain fully and primarily liable therefor and the liability of
          Tenant and such assignee (or subtenant, as the


                                       37
<PAGE>
            case may be) shall be joint and several. Further, and
            notwithstanding the foregoing, the provisions hereof shall not
            constitute a recognition of the assignment or the assignee
            thereunder or the sublease or the subtenant thereunder, as the case
            may be, and at Landlord's option, upon the termination of the Lease,
            the assignment or sublease shall be terminated.

      (B)   As Additional Rent, Tenant shall reimburse Landlord promptly for
            reasonable out of pocket legal and other expenses incurred by
            Landlord in connection with any request by Tenant for consent to
            assignment or subletting (such legal expenses not to exceed
            $2,500.00 in connection with any single request for consent).

      (C)   If this Lease be assigned, or if the Premises or any part thereof be
            sublet or occupied by anyone other than Tenant, Landlord may upon
            prior notice to Tenant, at any time and from time to time following
            the occurrence of an Event of Default hereunder, collect rent and
            other charges from the assignee, sublessee or occupant and apply the
            net amount collected to the rent and other charges herein reserved,
            but no such assignment, subletting, occupancy or collection shall be
            deemed a waiver of this covenant, or a waiver of the provisions of
            Sections 5.6 through 5.6.5 hereof, or the acceptance of the
            assignee, sublessee or occupant as a tenant or a release of Tenant
            from the further performance by Tenant of covenants on the part of
            Tenant herein contained, the Tenant herein named to remain primarily
            liable under this Lease.

      (D)   The consent by Landlord to an assignment or subletting under any of
            the provisions of Sections 5.6.1 or 5.6.2 shall in no way be
            construed to relieve Tenant from obtaining the express consent in
            writing of Landlord to any further assignment or subletting.

      (E)   On or after the occurrence and during the continuation of an "Event
            of Default" (defined in Section 7.1), Landlord shall be entitled to
            one hundred percent (100%) of any Assignment/Sublease Profits
            (provided, however, that fifty percent (50%) of such
            Assignment/Sublease Profits shall be credited against amounts due
            and payable from Tenant on account of Annual Fixed Rent for such
            period).

      (F)   In addition to the other requirements set forth in this Lease and
            notwithstanding any other provision of this Lease, partial
            sublettings of the Premises shall only be permitted under the
            following terms and conditions: (i) the layout of both the subleased
            premises and the remainder of the Premises must comply with
            applicable laws, ordinances, rules and/or regulations and be
            approved by Landlord, including, without limitation, all
            requirements concerning access and egress, such approval not to be
            unreasonably withheld, conditioned or delayed; (ii) in the event the
            subleased premises are separately physically demised from the
            remainder of the Premises, Tenant shall pay all costs of separately
            physically demising the subleased premises; and (iii) there shall be
            no more than seven (7) subleases in effect for the Premises at any
            given time.


                                       38
<PAGE>
5.7   INDEMNITY; INSURANCE. (A) To defend with counsel first approved by
      Landlord (which approval shall not be unreasonably withheld or delayed),
      save harmless, and indemnify Landlord from any liability for injury, loss,
      accident or damage to any person or property, and from any claims,
      actions, proceedings and expenses and costs in connection therewith
      (including without limitation reasonable counsel fees) (i) arising from or
      claimed to have arisen from (a) the omission, fault, willful act,
      negligence or other misconduct of Tenant or Tenant's contractors,
      licensees, invitees, agents, servants, independent contractors or
      employees or (b) any use made or thing done or occurring on the Premises
      not due to the omission, fault, willful act, negligence or other
      misconduct of Landlord, or (ii) resulting from the failure of Tenant to
      perform and discharge its covenants and obligations under this Lease.

      (B)   To maintain commercial general liability insurance or comprehensive
      general liability insurance written on an occurrence basis with a broad
      form comprehensive liability endorsement covering the Premises insuring
      Landlord and Landlord's managing agent (and such persons as are in privity
      of estate with Landlord and Landlord's managing agent as may be set out in
      notice from time to time) as additional insureds as well as Tenant with
      limits which (i) may be maintained via an umbrella policy and (ii) shall,
      at the commencement of the Term, be at least equal to those stated in
      Section 1.1 and from time to time during the Term shall be for such higher
      limits, if any, as are customarily carried in Greater Boston with respect
      to similar properties or which may reasonably be required by Landlord, and
      worker's compensation insurance with statutory limits covering all of
      Tenant's employees working in the Premises, and to deposit with Landlord
      on or before the Commencement Date and concurrent with all renewals
      thereof, certificates for such insurance bearing the endorsement that the
      policies will not be canceled until after thirty (30) days' written notice
      to Landlord. All insurance required to be maintained by Tenant pursuant to
      this Lease shall be maintained with responsible companies qualified to do
      business, and in good standing, in the Commonwealth of Massachusetts and
      which have a rating of at least "A-" and are within a financial size
      category of not less than "Class VIII" in the most current Best's Key
      Rating Guide or such similar rating as may be reasonably selected by
      Landlord if such Guide is no longer published. Any and all such insurance
      (x) may be maintained under a blanket policy affecting other properties of
      Tenant and (y) may be written with deductibles as determined by Tenant
      and, as affect the Premises, reasonably approved by Landlord.

5.8   PERSONAL PROPERTY AT TENANT'S RISK. That all of the furnishings, fixtures,
      equipment, effects and property of every kind, nature and description of
      Tenant and of all persons claiming by, through or under Tenant which,
      during the continuance of this Lease or any occupancy of the Premises by
      Tenant or anyone claiming under Tenant, may be on the Premises or
      elsewhere in the Building or on the Site, 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, except that Landlord shall in no event be indemnified or held


                                       39
<PAGE>
      harmless or exonerated from any liability to Tenant or to any other
      person, for any injury, loss, damage or liability to the extent such
      indemnity, hold harmless or exoneration is prohibited by law or to the
      extent that such loss, damage or liability is caused by the negligence or
      willful misconduct of Landlord. Further, Tenant, at Tenant's expense,
      shall maintain at all times during the Term of this Lease insurance
      against loss or damage covered by so-called "all risk" type insurance
      coverage with respect to Tenant's fixtures, equipment, goods, wares and
      merchandise, tenant improvements made by or paid for by Tenant, and other
      property of Tenant (collectively "Tenant's Property"). Such insurance
      shall be in an amount at least equal to the full replacement cost of
      Tenant's Property.

5.9   RIGHT OF ENTRY. To permit Landlord and its agents to examine the Premises
      at reasonable times and upon reasonable prior notice (except in the event
      of an emergency) and, if Landlord shall so elect, to make any repairs or
      replacements Landlord may deem necessary; to remove, at Tenant's expense,
      any alterations, addition, signs, curtains, blinds, shades, awnings,
      aerials, flagpoles, or the like not consented to in writing; and to show
      the Premises to prospective tenants during the nine (9) months preceding
      expiration of the Term and to prospective purchasers and mortgagees at all
      reasonable times. In connection with its exercise of the rights set forth
      herein, Landlord shall use reasonable efforts to minimize interference
      with Tenant's business operations at the Premises to the extent reasonably
      practicable under the circumstances.

5.10  FLOOR LOAD; PREVENTION OF VIBRATION AND NOISE. Not to place a load upon
      the Premises exceeding an average rate of 70 pounds of live load per
      square foot of floor area (partitions shall be considered as part of the
      live load); and not to move any safe, vault or other heavy equipment in,
      about or out of the Premises except in such manner and at such time as
      Landlord shall in each instance authorize; Tenant's business machines and
      mechanical equipment which cause vibration or noise that may be
      transmitted to the Building structure or to any other space in the
      Building shall be so installed, maintained and used by Tenant so as to
      eliminate such vibration or noise.

5.11  PERSONAL PROPERTY TAXES. To pay promptly when due all taxes which may be
      imposed upon Tenant's Property in the Premises to whomever assessed.

5.12  COMPLIANCE WITH LAWS. To comply with all applicable Legal Requirements now
      or hereafter in force which shall impose a duty on Landlord or Tenant
      relating to or as a result of the use or occupancy of the Premises;
      provided that Tenant shall not be required to make any alterations or
      additions to the structure, roof, exterior and load bearing walls,
      foundation, structural floor slabs and other structural elements of the
      Building unless the same are required by such Legal Requirements as a
      result of or in connection with Tenant's use or occupancy of the Premises
      beyond normal use of space of this kind. Tenant shall promptly pay all
      fines, penalties and damages that may arise out of or be imposed because
      of its failure to comply with the provisions of this Section 5.12.
      Notwithstanding the foregoing, except to the extent caused by Tenant or
      its employees, agents or contractors, Tenant shall not be obligated to
      correct any violations of laws,


                                       40
<PAGE>
      regulations or code existing in the Premises as of the Commencement Date
      (which such violations shall be remedied by Landlord).

5.13  PAYMENT OF LITIGATION EXPENSES. As Additional Rent, to pay all reasonable
      costs, counsel and other fees incurred by Landlord in connection with the
      successful enforcement by Landlord of any obligations of Tenant under this
      Lease or in connection with any bankruptcy case involving Tenant or any
      guarantor (Landlord hereby similarly agreeing to pay all reasonable costs,
      counsel and other fees incurred by Tenant in connection with the
      successful enforcement by Tenant of any obligations of Landlord under this
      Lease).

                                   ARTICLE VI

                              CASUALTY AND TAKING

6.0   LANDLORD'S RESTORATION ESTIMATE. In case during the Lease Term the
      Building or Site are damaged by fire or other casualty, Landlord shall
      within forty-five (45) days after the occurrence thereof notify Tenant in
      writing of Landlord's reasonable estimate of the length of time necessary
      to repair or restore such fire or casualty damage from the time that
      repair work would commence ("Landlord's Restoration Estimate").

6.1   DAMAGE RESULTING FROM CASUALTY. In case during the Lease Term the Building
      or the Site are damaged by fire or casualty, and if according to
      Landlord's Restoration Estimate such fire or casualty damage cannot, in
      the ordinary course, reasonably be expected to be repaired within three
      hundred (300) days from the time that repair work would commence, either
      party may, at its election, terminate this Lease by notice given to the
      other party within sixty (60) days after the date of such fire or other
      casualty, specifying the effective date of termination. The effective date
      of termination specified by the terminating party shall not be less than
      thirty (30) days nor more than forty-five (45) days after the date of
      notice of such termination.

      In case during the last year of the Lease Term, the Premises are damaged
      by fire or casualty and such fire or casualty damage cannot, in the
      ordinary course, reasonably be expected to be repaired within the lesser
      of (x) one hundred fifty (150) days from the time that repair work would
      commence, or (y) the number of days then remaining in the Lease Term,
      Tenant may, at its election, terminate this Lease by notice given to
      Landlord within sixty (60) days after the date of such fire or other
      casualty, specifying the effective date of termination. The effective date
      of termination specified by Tenant shall be not less than thirty (30) days
      nor more than forty-five (45) days after the date of notice of such
      termination.

      Unless terminated pursuant to the foregoing provisions, this Lease shall
      remain in full force and effect following any such damage subject,
      however, to the following provisions.


                                       41
<PAGE>
      If the Building or the Site or any part thereof are damaged by fire or
      other casualty and this Lease is not so terminated, or Landlord or Tenant
      have no right to terminate this Lease, and in any such case the holder of
      any mortgage which includes the Building as a part of the mortgaged
      premises or any ground lessor of any ground lease which includes the Site
      as part of the demised premises allows the net insurance proceeds to be
      applied to the restoration of the Building (and/or the Site), Landlord
      promptly after such damage and the determination of the net amount of
      insurance proceeds available shall use due diligence to restore the
      Premises and the Building in the event of damage thereto (excluding
      Tenant's Property) into proper condition for use and occupation and a just
      proportion of the Annual Fixed Rent, Tenant's share of Operating Costs and
      Tenant's share of real estate taxes according to the nature and extent of
      the injury to the Premises shall be abated until the Premises shall have
      been put by Landlord substantially into such condition except for punch
      list items and long lead items of such a nature that Tenant can reasonably
      use the Premises for the Permitted Use notwithstanding the fact that such
      long lead items have not been completed. Notwithstanding anything herein
      contained to the contrary, Landlord shall not be obligated to expend for
      such repair and restoration any amount in excess of the net insurance
      proceeds.

      Unless such restoration is completed within ten (10) months from the date
      of the casualty or taking, such period to be subject, however, to
      extension where the delay in completion of such work is due to causes
      beyond Landlord's reasonable control (but in no event beyond twelve (12)
      months from the date of the casualty or taking), Tenant, as its sole and
      exclusive remedy, shall have the right to terminate this Lease at any time
      after the expiration of such ten-month (as extended) period until the
      restoration is substantially completed, such termination to take effect as
      of the thirtieth (30th) day after the date of receipt by Landlord of
      Tenant's notice, with the same force and effect as if such date were the
      date originally established as the expiration date hereof unless, within
      thirty (30) days after Landlord's receipt of Tenant's notice, such
      restoration is substantially completed, in which case Tenant's notice of
      termination shall be of no force and effect and this Lease and the Lease
      Term shall continue in full force and effect.

6.2   UNINSURED CASUALTY. Notwithstanding anything to the contrary contained in
      this Lease, if the Building or the Premises shall be substantially damaged
      by fire or casualty as the result of a risk not covered by the forms of
      casualty insurance at the time maintained by Landlord (or required to be
      maintained by Landlord hereunder) and such fire or casualty damage cannot,
      in the ordinary course, reasonably be expected to be repaired within
      ninety (90) days from the time that repair work would commence, Landlord
      may, at its election, terminate the Term of this Lease by notice to the
      Tenant given within sixty (60) days after such loss. If Landlord shall
      give such notice, then this Lease shall terminate as of the date of such
      notice with the same force and effect as if such date were the date
      originally established as the expiration date hereof.

6.3   RIGHTS OF TERMINATION FOR TAKING. If the entire Building, or such portion
      of the Premises as to render the balance (if reconstructed to the maximum
      extent practicable


                                       42
<PAGE>
      in the circumstances) unsuitable for Tenant's purposes, shall be taken by
      condemnation or right of eminent domain, Landlord or Tenant shall have the
      right to terminate this Lease by notice to the other of its desire to do
      so, provided that such notice is given not later than thirty (30) days
      after Tenant has been deprived of possession. If either party shall give
      such notice, then this Lease shall terminate as of the date of such notice
      with the same force and effect as if such date were the date originally
      established as the expiration date hereof.

      Further, if so much of the Building shall be so taken that continued
      operation of the Building would be uneconomic as a result of the taking,
      Landlord shall have the right to terminate this Lease by giving notice to
      Tenant of Landlord's desire to do so not later than thirty (30) days after
      Tenant has been deprived of possession of the Premises (or such portion
      thereof as may be taken). If Landlord shall give such notice, then this
      Lease shall terminate as of the date of such notice with the same force
      and effect as if such date were the date originally established as the
      expiration date hereof.

      Should any part of the Premises be so taken or condemned during the Lease
      Term hereof, and should this Lease not be terminated in accordance with
      the foregoing provisions, and the holder of any mortgage which includes
      the Premises as part of the mortgaged premises or any ground lessor of any
      ground lease which includes the Site as part of the demised premises
      allows the net condemnation proceeds to be applied to the restoration of
      the Building, Landlord agrees that after the determination of the net
      amount of condemnation proceeds available to Landlord, Landlord shall use
      due diligence to put what may remain of the Premises into proper condition
      for use and occupation as nearly like the condition of the Premises prior
      to such taking as shall be practicable (excluding Tenant's Property).
      Notwithstanding the foregoing, Landlord shall not be obligated to expend
      for such repair and restoration any amount in excess of the net
      condemnation proceeds made available to it.

      If the Premises shall be affected by any exercise of the power of eminent
      domain, then the Annual Fixed Rent, Tenant's share of operating costs and
      Tenant's share of real estate taxes shall be justly and equitably abated
      and reduced according to the nature and extent of the loss of use thereof
      suffered by Tenant; and in case of a taking which permanently reduces the
      Rentable Floor Area of the Premises, a just proportion of the Annual Fixed
      Rent, Tenant's share of operating costs and Tenant's share of real estate
      taxes shall be abated for the remainder of the Lease Term.

6.4   AWARD. Landlord shall have and hereby reserves to itself any and all
      rights to receive awards made for damages to the Premises, the Buildings,
      the Complex and the Site 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 grants, releases and assigns to Landlord all
      Tenant's rights to such awards, and covenants to execute and deliver such
      further assignments and assurances thereof as Landlord may from time to
      time request, and if Tenant shall fail to execute and deliver the same
      within fifteen (15) days after notice from Landlord, Tenant


                                       43
<PAGE>
      hereby covenants and agrees that Landlord shall be irrevocably designated
      and appointed as its attorney-in-fact to execute and deliver in Tenant's
      name and behalf all such further assignments thereof which conform with
      the provisions hereof.

      Nothing contained herein shall be construed to prevent Tenant from
      prosecuting in any condemnation proceeding a claim for the value of any of
      Tenant's usual trade fixtures installed in the Premises by Tenant at
      Tenant's expense and for relocation and moving expenses, provided that
      such action and any resulting award shall not affect or diminish the
      amount of compensation otherwise recoverable by Landlord from the taking
      authority.

                                  ARTICLE VII

                                    DEFAULT

7.1   TENANT'S DEFAULT. (a) If at any time subsequent to the date of this Lease
      any one or more of the following events (herein sometimes called an "Event
      of Default") shall occur:

            (i)   Tenant shall fail to pay the fixed rent, Additional Rent or
                  other charges for which provision is made herein on or before
                  the date on which the same become due and payable, and the
                  same continues for ten (10) days after written notice from
                  Landlord thereof; or

            (ii)  Landlord having rightfully given the notice specified in
                  subdivision (a) above twice in any calendar year, Tenant shall
                  thereafter in the same calendar year fail to pay the fixed
                  rent, Additional Rent or other charges on or before the date
                  on which the same become due and payable; or

            (iii) Tenant shall assign its interest in this Lease or sublet any
                  portion of the Premises in violation of the requirements of
                  Sections 5.6 through 5.6.5 of this Lease; or

            (iv)  Tenant shall neglect or fail to perform or observe any other
                  covenant herein contained on Tenant's part to be performed or
                  observed and Tenant shall fail to remedy the same within
                  thirty (30) days after written notice to Tenant specifying
                  such neglect or failure, or if such failure is of such a
                  nature that Tenant cannot reasonably remedy the same within
                  such thirty (30) day period, Tenant shall fail to commence
                  promptly to remedy the same and to prosecute such remedy to
                  completion with diligence and continuity; or

            (v)   Tenant's leasehold interest in the Premises shall be taken on
                  execution or by other process of law directed against Tenant;
                  or


                                       44
<PAGE>
            (vi)   Tenant shall make an assignment for the benefit of creditors
                   or shall file a voluntary petition in bankruptcy or shall be
                   adjudicated bankrupt or insolvent, or shall file any petition
                   or answer seeking any reorganization, arrangement,
                   composition, readjustment, liquidation, dissolution or
                   similar relief for itself under any present or future
                   Federal, State or other statute, law or regulation for the
                   relief of debtors, or shall seek or consent to or acquiesce
                   in the appointment of any trustee, receiver or liquidator of
                   Tenant or of all or any substantial part of its properties,
                   or shall admit in writing its inability to pay its debts
                   generally as they become due; or

            (vii)  A petition shall be filed against Tenant in bankruptcy or
                   under any other law seeking any reorganization, arrangement,
                   composition, readjustment, liquidation, dissolution, or
                   similar relief under any present or future Federal, State or
                   other statute, law or regulation and shall remain undismissed
                   or unstayed for an aggregate of ninety (90) days (whether or
                   not consecutive), or if any debtor in possession (whether or
                   not Tenant) trustee, receiver or liquidator of Tenant or of
                   all or any substantial part of its properties or of the
                   Premises shall be appointed without the consent or
                   acquiescence of Tenant and such appointment shall remain
                   unvacated or unstayed for an aggregate of ninety (90) days
                   (whether or not consecutive) then, and in any of said cases
                   (notwithstanding any license of a former breach of covenant
                   or waiver of the benefit hereof or consent in a former
                   instance), Landlord lawfully may, immediately or at any time
                   thereafter, and without demand or further notice terminate
                   this Lease by notice to Tenant, specifying a date not less
                   than ten (10) business days after the giving of such notice
                   on which this Lease shall terminate, and this Lease shall
                   come to an end on the date specified therein as fully and
                   completely as if such date were the date herein originally
                   fixed for the expiration of the Lease Term (Tenant hereby
                   waiving any rights of redemption), and Tenant will then quit
                   and surrender the Premises to Landlord, but Tenant shall
                   remain liable as hereinafter provided; or

            (viii) Tenant shall abandon the Premises in such a manner as to
                   create a hazard or nuisance in, or diminution in value to,
                   the Premises or the Building.

      (b)   If this Lease shall have been terminated as provided in this
            Article, then Landlord may, without notice, re-enter the Premises,
            either by force, summary proceedings, ejectment or otherwise, and
            remove and dispossess Tenant and all other persons and any and all
            property from the same, as if this Lease had not been made, and
            Tenant hereby waives the service of notice of intention to re-enter
            or to institute legal proceedings to that end.

      (c)   In the event that this Lease is terminated under any of the
            provisions contained in Section 7.1 (a) or shall be otherwise
            terminated by breach of any obligation of Tenant, Tenant covenants
            and agrees forthwith to pay and be liable for, on the


                                       45
<PAGE>
            days originally fixed herein for the payment thereof, amounts equal
            to the several installments of rent and other charges reserved as
            they would, under the terms of this Lease, become due if this Lease
            had not been terminated or if Landlord had not entered or
            re-entered, as aforesaid, and whether the Premises be relet or
            remain vacant, in whole or in part, or for a period less than the
            remainder of the Term, and for the whole thereof, but in the event
            the Premises be relet by Landlord, Tenant shall be entitled to a
            credit in the net amount of rent and other charges received by
            Landlord in reletting, after deduction of all reasonable expenses
            incurred in reletting the Premises (including, without limitation,
            remodeling costs, brokerage fees and the like), and in collecting
            the rent in connection therewith, in the following manner:

            Amounts received by Landlord after reletting shall first be applied
            against such Landlord's expenses, until the same are recovered, and
            until such recovery, Tenant shall pay, as of each day when a payment
            would fall due under this Lease, the amount which Tenant is
            obligated to pay under the terms of this Lease (Tenant's liability
            prior to any such reletting and such recovery not in any way to be
            diminished as a result of the fact that such reletting might be for
            a rent higher than the rent provided for in this Lease); when and if
            such expenses have been completely recovered, the amounts received
            from reletting by Landlord as have not previously been applied shall
            be credited against Tenant's obligations as of each day when a
            payment would fall due under this Lease, and only the net amount
            thereof shall be payable by Tenant. Further, amounts received by
            Landlord from such reletting for any period during what would have
            been the Term of this Lease had the same not been terminated shall
            be credited only against obligations of Tenant allocable to such
            period, and shall not be credited against obligations of Tenant
            hereunder accruing subsequent or prior to such period; nor shall any
            credit of any kind be due for any period after the date when the
            term of this Lease is scheduled to expire according to its terms.

      (d)   (i)   At any time after such termination and whether or not Landlord
            shall have collected any damages as aforesaid, as liquidated final
            damages and in lieu of all other damages beyond the date of notice
            from Landlord to Tenant, at Landlord's election, Tenant shall pay to
            Landlord such a sum as at the time of the giving of such notice
            represents the amount of the excess, if any, of the total rent and
            other benefits which would have accrued to Landlord under this Lease
            from the date of such notice for what would be the then unexpired
            Lease Term if the Lease terms had been fully complied with by Tenant
            over and above the then cash rental value (in advance) of the
            Premises for the balance of the Lease Term, discounted to present
            value at a discount rate equal to the then-prevailing prime rate in
            Boston as set by Fleet National Bank (or its successor).

      (d)   (ii)  For the purposes of this Article, if Landlord elects to
            require Tenant to pay damages in accordance with the immediately
            preceding paragraph, the total rent shall be computed by assuming
            that Tenant's share of excess taxes, Tenant's share


                                       46
<PAGE>
            of excess operating costs and Tenant's share of excess electrical
            costs would be, for the balance of the unexpired Term from the date
            of such notice, the amount thereof (if any) for the immediately
            preceding annual period payable by Tenant to Landlord.

      (e)   In case of any Event of Default, re-entry, dispossession by summary
            proceedings or otherwise, Landlord may (i) re-let the Premises or
            any part or parts thereof, either in the name of Landlord or
            otherwise, 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 of this Lease and may grant
            concessions, abatements or free rent to the extent that Landlord
            considers advisable or necessary to re-let the same and (ii) may
            make such alterations and repairs in the Premises as Landlord in its
            sole judgment considers advisable or necessary for the purpose of
            reletting the Premises; and the making of such alterations and
            repairs shall not operate or be construed to release Tenant from
            liability hereunder as aforesaid. Landlord shall in no event be
            liable in any way whatsoever for failure to re-let the Premises, or,
            in the event that the Premises are re-let, for failure to collect
            the rent under re-letting. Tenant hereby expressly waives any and
            all rights of redemption granted by or under any present or future
            laws in the event of Tenant being evicted or dispossessed, or in the
            event of Landlord obtaining possession of the Premises, by reason of
            the violation by Tenant of any of the covenants and conditions of
            this Lease.

      (f)   The specified remedies to which Landlord may resort hereunder are
            not intended to be exclusive of any remedies or means of redress to
            which Landlord may at any time be entitled lawfully, and Landlord
            may invoke any remedy (including the remedy of specific performance)
            allowed at law or in equity as if specific remedies were not herein
            provided for. Further, 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 proved, whether or
            not the amount be greater, equal to, or less than the amount of the
            loss or damages referred to above.

      (g)   In lieu of any other damages or indemnity and in lieu of the
            recovery by Landlord of all sums payable under all the foregoing
            provisions of this Section 7.1, Landlord may elect to collect from
            Tenant, by notice to Tenant, at any time after this Lease is
            terminated under any of the provisions contained in this Article VII
            or otherwise terminated by breach of any obligation of Tenant and
            before full recovery under such foregoing provisions, and Tenant
            shall thereupon pay, as liquidated damages, an amount equal to the
            sum of (x) the Annual Fixed Rent and all Additional Rent payable for
            the lesser of (i) the twelve (12) months ended next prior to such
            termination or (ii) the number of months then remaining in the Term
            of this Lease, plus (y) the amount of Annual Fixed Rent and
            Additional Rent of


                                       47

<PAGE>
                  any kind accrued and unpaid at the time of such election plus
                  any and all expenses which the Landlord may have incurred for
                  and with respect of the collection of any of such rent.

7.2      LANDLORD'S DEFAULT. Landlord shall in no event be in default in the
         performance of any of Landlord's obligations hereunder unless and until
         Landlord shall have failed to perform such obligations within thirty
         (30) days, or such additional time as is reasonably required to correct
         any such default, after notice by Tenant to Landlord properly
         specifying wherein Landlord has failed to perform any such obligation.

                                  ARTICLE VIII

8.1      EXTRA HAZARDOUS USE. Tenant covenants and agrees that Tenant will not
         do or permit anything to be done in or upon the Premises, or bring in
         anything or keep anything therein, which shall increase the rate of
         insurance on the Premises or on the Building above the standard rate
         applicable to premises being occupied for the use to which Tenant has
         agreed to devote the Premises; and Tenant further agrees that, in the
         event that Tenant shall do any of the foregoing, Tenant will promptly
         pay to Landlord, on demand, any such increase resulting therefrom,
         which shall be due and payable as Additional Rent thereunder.

8.2      WAIVER. Failure on the part of Landlord or Tenant to complain of any
         action or non-action on the part of the other, no matter how long the
         same may continue, shall never be a waiver by Tenant or Landlord,
         respectively, of any of its rights hereunder. Further, no waiver at any
         time of any of the provisions hereof by Landlord or Tenant shall be
         construed as a waiver of any of the other provisions hereof, and a
         waiver at any time of any of the provisions hereof shall not be
         construed as a waiver at any subsequent time of the same provisions.
         The consent or approval of Landlord or Tenant to or of any action by
         the other requiring such consent or approval shall not be construed to
         waive or render unnecessary Landlord's or Tenant's consent or approval
         to or of subsequent similar act by the other.

         No payment by Tenant, or acceptance by Landlord, of a lesser amount
         than shall be due from Tenant to Landlord shall be treated otherwise
         than as a payment on account. The acceptance by Landlord of a check for
         a lesser amount with an endorsement or statement thereon, or upon any
         letter accompanying such check, that such lesser amount is payment in
         full, shall be given no effect, and Landlord may accept such check
         without prejudice to any other rights or remedies which Landlord may
         have against Tenant.

8.3      CUMULATIVE REMEDIES. Except as expressly provided in this Lease, the
         specific remedies to which either party may resort under the terms of
         this Lease are cumulative and are not intended to be exclusive of any
         other remedies or means of redress to which any such party may be
         lawfully entitled in case of any breach or threatened breach by the
         other party of any provisions of this Lease. In addition to the other
         remedies provided in this Lease, the parties shall be entitled to the
         restraint by injunction of the violation or

                                       48
<PAGE>
         attempted or threatened violation of any of the covenants, conditions
         or provisions of this Lease or to a decree compelling specific
         performance of any such covenants, conditions or provisions.

8.4      QUIET ENJOYMENT. Tenant, subject to the terms and provisions of this
         Lease on payment of the rent and observing, keeping and performing all
         of the terms and provisions of this Lease on Tenant's part to be
         observed, kept and performed, shall lawfully, peaceably and quietly
         have, hold, occupy and enjoy the Premises during the Term (exclusive of
         any period during which Tenant is holding over after the expiration or
         termination of this Lease without the consent of Landlord), without
         hindrance or ejection by any persons lawfully claiming to have title to
         the Premises superior to Tenant, subject, however, to the terms of this
         Lease; the foregoing covenant of quiet enjoyment is in lieu of any
         other covenant, express or implied; and it is understood and agreed
         that this covenant and any and all other covenants of Landlord
         contained in this Lease shall be binding upon Landlord and Landlord's
         successors, including ground or master lessees, only with respect to
         breaches occurring during Landlord's or Landlord's successors'
         respective ownership of Landlord's interest hereunder, as the case may
         be.

         Further, Tenant specifically agrees to look solely to Landlord's then
         equity interest in the Building (including proceeds from sale,
         financing or insurance) at the time owned, or in which Landlord holds
         an interest as ground lessee, for recovery of any judgment from
         Landlord; it being specifically agreed that neither Landlord (original
         or successor), nor any beneficiary of any trust of which any person
         holding Landlord's interest is trustee, nor any member, manager,
         partner, director or stockholder, nor Landlord's managing agent, shall
         ever be personally liable for any such judgment, or for the payment of
         any monetary obligation to Tenant. The provision contained in the
         foregoing sentence is not intended to, and shall not, limit any right
         that Tenant might otherwise have to obtain injunctive relief against
         Landlord or Landlord's successors in interest, or any action not
         involving the personal liability of Landlord (original or successor),
         any successor trustee to the persons named herein as Landlord, or any
         beneficiary of any trust of which any person holding Landlord's
         interest is trustee, or of any manager, member, partner, director or
         stockholder of Landlord or of Landlord's managing agent to respond in
         monetary damages from Landlord's assets other than Landlord's equity
         interest aforesaid in the Building. In no event shall Landlord ever be
         liable to Tenant for any indirect or consequential damages or loss of
         profits or the like.

8.5      NOTICE TO MORTGAGEE AND GROUND LESSOR. After receiving notice from any
         person, firm or other entity that it holds a mortgage which includes
         the Premises as part of the mortgaged premises, or that it is the
         ground lessor under a lease with Landlord, as ground lessee, which
         includes the Premises as a part of the demised premises, no default
         notice from Tenant to Landlord shall be effective unless and until a
         copy of the same is given to such holder or ground lessor, and the
         curing of any of Landlord's defaults by such holder or ground lessor
         within a reasonable time thereafter (not to exceed sixty (60) days or
         such shorter time period as may be agreed upon by Tenant and such
         mortgagee or ground lessor in a subordination, non-disturbance and
         attornment agreement) shall be

                                       49
<PAGE>
         treated as performance by Landlord. For the purposes of this Section
         8.5 or Section 8.15, the term "mortgage" includes a mortgage on a
         leasehold interest of Landlord (but not one on Tenant's leasehold
         interest).

8.6      ASSIGNMENT OF RENTS. With reference to any assignment by Landlord of
         Landlord's interest in this Lease, or the rents payable hereunder,
         conditional in nature or otherwise, which assignment is made to the
         holder of a mortgage or ground lease on property which includes the
         Premises, Tenant agrees:

                  (a)      That the execution thereof by Landlord, and the
                           acceptance thereof by the holder of such mortgage or
                           the ground lessor, shall never be treated as an
                           assumption by such holder or ground lessor of any of
                           the obligations of Landlord hereunder, unless such
                           holder, or ground lessor, shall, by notice sent to
                           Tenant, specifically otherwise elect; and

                  (b)      That, except as aforesaid, such holder or ground
                           lessor shall be treated as having assumed Landlord's
                           obligations hereunder only upon foreclosure of such
                           holder's mortgage and the taking of possession of the
                           Premises, or, in the case of a ground lessor, the
                           assumption of Landlord's position hereunder by such
                           ground lessor.

                           In no event shall the acquisition of title to the
                           Building and the land on which the same is located by
                           a purchaser which, simultaneously therewith, leases
                           the entire Building or such land back to the seller
                           thereof be treated as an assumption by such
                           purchaser-lessor, by operation of law or otherwise,
                           of Landlord's obligations hereunder, but Tenant shall
                           look solely to such seller-lessee, and its successors
                           from time to time in title, for performance of
                           Landlord's obligations hereunder subject to the
                           provisions of Section 8.4 hereof. In any such event,
                           this Lease shall be subject and subordinate to the
                           lease to such purchaser provided that such purchaser
                           agrees to recognize the right of Tenant to use and
                           occupy the Premises upon the payment of rent and
                           other charges payable by Tenant under this Lease and
                           the performance by Tenant of Tenant's obligations
                           hereunder and provided that Tenant agrees to attorn
                           to such purchaser. For all purposes, such
                           seller-lessee, and its successors in title, shall be
                           the landlord hereunder unless and until Landlord's
                           position shall have been assumed by such
                           purchaser-lessor.

8.7      SURRENDER. No act or thing done by Landlord during the Lease Term shall
         be deemed an acceptance of a surrender of the Premises, and no
         agreement to accept such surrender shall be valid, unless in writing
         signed by Landlord. No employee of Landlord or of Landlord's agents
         shall have any power to accept the keys of the Premises prior to the
         termination of this Lease. The delivery of keys to any employee of
         Landlord or of Landlord's agents shall not operate as a termination of
         the Lease or a surrender of the Premises.


                                       50
<PAGE>
8.8      BROKERAGE. (A) Tenant warrants and represents that Tenant has not dealt
         with any broker in connection with the consummation of this Lease other
         than the broker, person or firm, if any, designated in Section 1.1
         hereof (the "Brokers"); and in the event any claim is made against the
         Landlord relative to dealings by Tenant with brokers other than the
         Brokers, Tenant shall defend the claim against Landlord with counsel of
         Tenant's selection first approved by Landlord (which approval will not
         be unreasonably withheld) and save harmless and indemnify Landlord on
         account of loss, cost or damage which may arise by reason of such
         claim.

         (B) Landlord warrants and represents that Landlord has not dealt with
         any broker in connection with the consummation of this Lease other than
         the Brokers; and in the event any claim is made against the Tenant
         relative to dealings by Landlord with brokers other than the Brokers,
         Landlord shall defend the claim against Tenant with counsel of
         Landlord's selection and save harmless and indemnify Tenant on account
         of loss, cost or damage which may arise by reason of such claim.
         Landlord agrees that it shall be solely responsible for the payment of
         brokerage commissions to the Brokers for the Original Term of this
         Lease and, to the extent any such commission is due and payable in
         connection therewith, for the Extended Term (if exercised).

8.9      INVALIDITY OF PARTICULAR PROVISIONS. If any term or provision of this
         Lease, or the application thereof to any person or circumstance shall,
         to any extent, be invalid or unenforceable, the remainder of this
         Lease, or the application of such term or provision to persons or
         circumstances other than those as to which it is held invalid or
         unenforceable, shall not be affected thereby, and each term and
         provision of this Lease shall be valid and be enforced to the fullest
         extent permitted by law.

8.10     PROVISIONS BINDING, ETC. The obligations of this Lease shall run with
         the land, and except as herein otherwise provided, the terms hereof
         shall be binding upon and shall inure to the benefit of the successors
         and assigns, respectively, of Landlord and Tenant and, if Tenant shall
         be an individual, upon and to his heirs, executors, administrators,
         successors and assigns. Each term and each provision of this Lease to
         be performed by Tenant shall be construed to be both a covenant and a
         condition. The reference contained to successors and assigns of Tenant
         is not intended to constitute a consent to subletting or assignment by
         Tenant.

8.11     RECORDING. Tenant agrees not to record the within Lease, but each party
         hereto agrees, on the request of the other, to execute a so-called
         Notice of Lease or short form lease in form recordable and complying
         with applicable law and reasonably satisfactory to both Landlord's and
         Tenant's attorneys. In no event shall such document set forth rent or
         other charges payable by Tenant under this Lease; and any such document
         shall expressly state that it is executed pursuant to the provisions
         contained in this Lease, and is not intended to vary the terms and
         conditions of this Lease.


                                       51
<PAGE>
8.12     NOTICES. Whenever, by the terms of this Lease, notice shall or may be
         given either to Landlord or to Tenant, such notice shall be in writing
         and shall be sent by registered or certified mail postage prepaid:

         If intended for Landlord, addressed to Landlord at the address set
         forth on the first page of this Lease (or to such other address or
         addresses as may from time to time hereafter be designated by Landlord
         by like notice) with a copy to Landlord, Attention: General Counsel.

         If intended for Tenant, addressed to Tenant at the address set forth on
         the second page of this Lease except that from and after the
         Commencement Date the address of Tenant shall be the Premises (or to
         such other address or addresses as may from time to time hereafter be
         designated by Tenant by like notice), with a courtesy copy to Jennifer
         C. Platt, Esq. at Hutchins, Wheeler & Dittmar, P.C., 101 Federal
         Street, Boston, Massachusetts 02110.

         Except as otherwise provided herein, all such notices shall be
         effective when received; provided, that (i) if receipt is refused,
         notice shall be effective upon the first occasion that such receipt is
         refused or (ii) if the notice is unable to be delivered due to a change
         of address of which no notice was given, notice shall be effective upon
         the date such delivery was attempted.

         Where provision is made for the attention of an individual or
         department, the notice shall be effective only if the wrapper in which
         such notice is sent is addressed to the attention of such individual or
         department.

         Any notice given by an attorney on behalf of Landlord or Tenant or by
         Landlord's managing agent shall be considered as given by Landlord or
         Tenant, as appropriate, and shall be fully effective.

         Time is of the essence with respect to any and all notices and periods
         for giving notice or taking any action thereto under this Lease.

8.13     WHEN LEASE BECOMES BINDING. Employees or agents of Landlord have no
         authority to make or agree to make a lease or any other agreement or
         undertaking in connection herewith. The submission of this document for
         examination and negotiation does not constitute an offer to lease, or a
         reservation of, or option for, the Premises, and this document shall
         become effective and binding only upon the execution and delivery
         hereof by both Landlord and Tenant. All negotiations, considerations,
         representations and understandings between Landlord and Tenant are
         incorporated herein and may be modified or altered only by written
         agreement between Landlord and Tenant, and no act or omission of any
         employee or agent of Landlord shall alter, change or modify any of the
         provisions hereof.

8.14     SECTION HEADINGS. The titles of the Articles throughout this Lease are
         for convenience and reference only, and the words contained therein
         shall in no way be held

                                       52
<PAGE>
         to explain, modify, amplify or aid in the interpretation, construction
         or meaning of the provisions of this Lease.

8.15     RIGHTS OF MORTGAGEE. This Lease shall be subject and subordinate to any
         mortgage now or hereafter on the Site or the Building, or both, 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 that the
         holder of such mortgage agrees to recognize the rights of Tenant under
         this Lease (including the right to use and occupy the Premises) upon
         the payment of rent and other charges payable by Tenant under this
         Lease and the performance by Tenant of Tenant's obligations hereunder.
         In confirmation of such subordination and recognition, Tenant shall
         execute and deliver promptly such instruments of subordination and
         recognition as such mortgagee may reasonably request. Landlord agrees
         to use reasonable efforts to obtain a subordination, non-disturbance
         and attornment agreement from the current mortgagee of the Site. In the
         event that any mortgagee or its respective successor in title shall
         succeed to the interest of Landlord, then, this Lease shall
         nevertheless continue in full force and effect and Tenant shall and
         does hereby agree to attorn to such mortgagee or successor and to
         recognize such mortgagee or successor as its landlord provided that
         such mortgagee or successor agrees to recognize the rights of Tenant
         under this Lease (including the right to use and occupy the Premises)
         upon the payment of rent and other charges payable by Tenant under this
         Lease and the performance by Tenant of Tenant's obligations hereunder.
         If any holder of a mortgage which includes the Premises, executed and
         recorded prior to the date of this Lease, shall so elect, this Lease
         and the rights of Tenant hereunder, shall be superior in right to the
         rights of such holder, with the same force and effect as if this Lease
         had been executed, delivered and recorded, or a statutory Notice hereof
         recorded, prior to the execution, delivery and recording of any such
         mortgage. The election of any such holder shall become effective upon
         either notice from such holder to Tenant in the same fashion as notices
         from Landlord to Tenant are to be given hereunder or by the recording
         in the appropriate registry or recorder's office of an instrument in
         which such holder subordinates its rights under such mortgage to this
         Lease.

         If in connection with obtaining financing a bank, insurance company,
         pension trust or other institutional lender shall request reasonable
         modifications in this Lease as a condition to such financing, Tenant
         will not unreasonably withhold, delay or condition its consent thereto,
         provided that such modifications do not increase the monetary
         obligations of Tenant hereunder or materially adversely affect the
         leasehold interest hereby created.

8.16     STATUS REPORTS AND FINANCIAL STATEMENTS. Recognizing that Landlord may
         find it necessary to establish to third parties, such as accountants,
         banks, potential or existing mortgagees, potential purchasers or the
         like, the then current status of performance hereunder, Tenant, on the
         request of Landlord made from time to time, will promptly furnish to
         Landlord, or any existing or potential holder of any mortgage
         encumbering the Premises, the Building, the Site and/or the Complex or
         any potential

                                       53
<PAGE>
         purchaser of the Premises, the Building, the Site and/or the Complex,
         (each an "Interested Party"), a statement of the status of any matter
         pertaining to this Lease, including, without limitation,
         acknowledgments that (or the extent to which) each party is in
         compliance with its obligations under the terms of this Lease. In
         addition, Tenant shall deliver to Landlord, or any Interested Party
         designated by Landlord, financial statements of Tenant and any
         guarantor of Tenant's obligations under this Lease, as reasonably
         requested by Landlord no more frequently than once during any twelve
         (12) month period, including, but not limited to financial statements
         for the past three (3) years (provided, however, that the provisions of
         this sentence shall be inapplicable for so long as Tenant is a public
         company whose stock is traded on a national exchange). Any such status
         statement or financial statement delivered by Tenant pursuant to this
         Section 8.16 may be relied upon by any Interested Party.

8.17     SELF-HELP. If Tenant shall at any time default beyond the expiration of
         any applicable notice and cure periods provided in this Lease (except
         in the event of an emergency situation, in which event Landlord may act
         prior to the expiration of any applicable cure period) in the
         performance of any obligation under this Lease, Landlord shall have the
         right, but shall not be obligated, to enter upon the Premises and to
         perform such obligation notwithstanding the fact that no specific
         provision for such substituted performance by Landlord is made in this
         Lease with respect to such default. In performing such obligation,
         Landlord may make any payment of money or perform any other act. All
         sums so paid by Landlord (together with interest at the rate of two and
         one-half percentage points over the then prevailing prime rate in
         Boston as set by Fleet National Bank or its successor (but in no event
         greater than the maximum rate permitted by applicable law) and all
         costs and expenses in connection with the performance of any such act
         by Landlord, shall be deemed to be Additional Rent under this Lease and
         shall be payable to Landlord immediately on demand. Landlord may
         exercise the foregoing rights without waiving any other of its rights
         or releasing Tenant from any of its obligations under this Lease.

8.18     HOLDING OVER. Any holding over by Tenant after the expiration of the
         term of this Lease shall be treated as a tenancy at sufferance and
         shall be on the terms and conditions as set forth in this Lease, as far
         as applicable except that Tenant shall pay as a use and occupancy
         charge an amount equal to the greater of (x) 150% of the Annual Fixed
         Rent and Additional Rent calculated (on a daily basis) at the highest
         rate payable under the terms of this Lease, or (y) the fair market
         rental value of the Premises, in each case for the period measured from
         the day on which Tenant's hold-over commences and terminating on the
         day on which Tenant vacates the Premises. In addition, Tenant shall
         save Landlord, its agents and employees harmless and will exonerate,
         defend and indemnify Landlord, its agents and employees from and
         against any and all damages which Landlord may suffer on account of
         Tenant's hold-over in the Premises after the expiration or prior
         termination of the term of this Lease. Nothing in the foregoing nor any
         other term or provision of this Lease shall be deemed to permit Tenant
         to retain possession of the Premises or hold over in the Premises after
         the expiration or earlier termination of the Lease Term. All property
         which remains in the Building or the Premises after the

                                       54
<PAGE>
         expiration or termination of this Lease shall be conclusively deemed to
         be abandoned and may either be retained by Landlord as its property or
         sold or otherwise disposed of in such manner as Landlord may see fit.
         If any part thereof shall be sold, then Landlord may receive the
         proceeds of such sale and apply the same, at its option against the
         expenses of the sale, the cost of moving and storage, any arrears of
         rent or other charges payable hereunder by Tenant to Landlord and any
         damages to which Landlord may be entitled under this Lease and at law
         and in equity.

8.19     NON-SUBROGATION. Any insurance carried by either party with respect to
         the Premises or property therein or occurrences thereon shall, if it
         can be so written without additional premium or with an additional
         premium which the other party agrees to pay, include a clause or
         endorsement denying to the insurer rights of subrogation against the
         other party to the extent rights have been waived by the insured prior
         to occurrence of injury or loss. Each party, notwithstanding any
         provisions of this Lease to the contrary, hereby waives any rights of
         recovery against the other for injury or loss due to hazards covered by
         such insurance to the extent of the indemnification received
         thereunder. In addition, this waiver of rights by Tenant shall apply
         to, and be for the benefit of, Landlord's managing agent.

8.20     EXTENSION OPTION. (A) On the conditions (which conditions Landlord may
         waive by written notice to Tenant) that at the time of exercise of the
         herein described option to extend (i) there exists no "Event of
         Default" (defined in Section 7.1), (ii) this Lease is still in full
         force and effect, and (iii) Tenant has neither assigned this Lease nor
         sublet in the aggregate thirty-three percent (33%) or more of the
         Rentable Floor Area of the Premises (except for an assignment or
         subletting permitted without Landlord's consent under Section 5.6.1
         hereof), Tenant shall have the right to extend the Term hereof upon all
         the same terms, conditions, covenants and agreements herein contained
         (except for the Annual Fixed Rent which shall be adjusted during the
         option period as hereinbelow set forth and except that there shall be
         no further option to extend) for one (1) period of five (5) years as
         hereinafter set forth. The option period is sometimes herein referred
         to as the "Extended Term." Notwithstanding any implication to the
         contrary Landlord has no obligation to make any additional payment to
         Tenant in respect of any construction allowance or the like or to
         perform any work to the Premises as a result of the exercise by Tenant
         of any such option.

         (B) If Tenant desires to exercise its option to extend the Term, then
         Tenant shall give notice to Landlord, not earlier than eighteen (18)
         months nor later than fifteen (15) months prior to the expiration of
         the Term of this Lease of Tenant's request for Landlord's quotation to
         Tenant of a proposed Annual Fixed Rent for the Extended Term. If at the
         expiration of thirty (30) days after the date when Landlord receives
         Tenant's written request as aforesaid (the "Negotiation Period"),
         Landlord and Tenant have not reached agreement on a determination of an
         Annual Fixed Rent for such Extended Term and executed a written
         instrument extending the Term of this Lease pursuant to such agreement,
         then Tenant shall have the right, for ten (10) days following the
         expiration of the Negotiation Period, to either (i) revoke its exercise
         of the extension option or (ii)

                                       55
<PAGE>
         make a request to Landlord for a broker determination (the "Broker
         Determination") of the Prevailing Market Rent (as defined in Exhibit F)
         for the Extended Term, which Broker Determination shall be made in the
         manner set forth in Exhibit F. If Tenant timely shall have requested
         the Broker Determination, then the Annual Fixed Rent for such Extended
         Term shall be the greater of (a) ninety-five percent (95%) of the
         Prevailing Market Rent as determined by the Broker Determination or (b)
         the Annual Fixed Rent in effect during the last twelve (12) month
         period of the Lease Term immediately prior to such Extended Term.

         (C) Upon either (a) the agreement by the parties on the Annual Fixed
         Rent for the Extended Term during the Negotiation Period or (b) the
         timely delivery by Tenant of notice to Landlord requesting the Broker
         Determination in accordance with Section 8.20(B) above, then this Lease
         and the Lease Term hereof shall automatically be deemed extended, for
         the Extended Term, without the necessity for the execution of any
         additional documents, except that Landlord and Tenant agree to enter
         into an instrument in writing setting forth the Annual Fixed Rent for
         the Extended Term as determined in the relevant manner set forth in
         this Section 8.20; and in such event all references herein to the Lease
         Term or the Term of this Lease shall be construed as referring to the
         Lease Term, as so extended, unless the context clearly otherwise
         requires, and except that there shall be no further option to extend
         the Lease Term. Notwithstanding anything contained herein to the
         contrary, in no event shall the Lease Term hereof be extended for more
         than five (5) years after the expiration of the Original Lease Term
         hereof.

8.21     SECURITY DEPOSIT. (A) Concurrently with the execution of this Lease,
         Tenant shall pay to Landlord a security deposit in the amount of Six
         Hundred Seventy-Nine Thousand Seven Hundred Eighty-Seven and 50/100
         Dollars ($679,787.50) and Landlord shall hold the same, throughout the
         Term of this Lease, as security for the performance by Tenant of all
         obligations on the part of Tenant to be performed under this Lease.
         Such deposit shall be in the form of an irrevocable, unconditional,
         negotiable letter of credit (the "Letter of Credit"). The Letter of
         Credit shall (i) be issued by and drawn on a bank reasonably approved
         by Landlord and at a minimum having a corporate credit rating from
         Standard & Poor's Professional Rating Service of BBB- or comparable
         minimum rating from Moody's Professional Rating Service, (ii) be in a
         form reasonably acceptable to Landlord, (iii) permit one or more draws
         thereunder to be made accompanied by a certification by Landlord that
         pursuant to the terms of this Lease, Landlord is entitled to draw upon
         such Letter of Credit, (iv) permit transfers or pledges at any time
         without charge to any purchase of the Building or Landlord's interest
         therein or to any lender as security for a loan and (v) permit
         presentment in Boston, Massachusetts. Any such Letter of Credit shall
         be for a term of two (2) years (or for one (1) year if the issuer
         thereof regularly and customarily only issues letters of credit for a
         maximum term of one (1) year) and shall in either case provide for
         automatic renewals through the date which is thirty (30) days
         subsequent to the scheduled expiration of this Lease or if the issuer
         will not grant automatic renewals, the Letter of Credit shall be
         renewed or substituted (by substitute Letter of Credit) by Tenant each
         year and each renewal or substitution Letter of Credit shall be
         delivered to and received by Landlord not later than thirty (30) days
         before the

                                       56
<PAGE>
         expiration of the then current Letter of Credit (herein called a
         "Renewal Presentation Date"). In the event of a failure to so deliver
         such renewal or substitution Letter of Credit on or before the
         applicable Renewal Presentation Date, Landlord shall be entitled to
         present the then existing Letter of Credit for payment and to receive
         the proceeds thereof, which proceeds shall be held as Tenant's security
         deposit, subject to the terms of this Section 8.21. Upon the occurrence
         and during the continuation of any Event of Default on the part of
         Tenant under the terms of this Lease, Landlord shall have the right
         from time to time without prejudice to any other remedy Landlord may
         have on account thereof, to draw on all or any portion of such deposit
         held as a Letter of Credit and to apply the proceeds of such Letter of
         Credit or any cash held as such deposit, or any part thereof, to
         Landlord's damages arising from such default. If Landlord so applies
         all or any portion of such deposit, Tenant shall within ten (10) days
         after notice from Landlord deposit cash with Landlord or increase the
         amount of the Letter of Credit in an amount sufficient to restore such
         deposit to the full amount stated in this Section 8.21. While Landlord
         holds any cash deposit Landlord shall have no obligation to pay
         interest on the same and shall have the right to commingle the same
         with Landlord's other funds. Neither the holder of a mortgage nor the
         Landlord in a ground lease on property which includes the Premises
         shall ever be responsible to Tenant for the return or application of
         any such deposit, whether or not it succeeds to the position of
         Landlord hereunder, unless such deposit shall have been received in
         hand by such holder or ground Landlord.

         (B) Provided that Tenant has maintained liquidity of at least
         $25,000,000.00 as of the fiscal quarter ending immediately prior to the
         scheduled reduction date set forth herein, Landlord shall exchange the
         Letter of Credit for a Letter of Credit delivered by Tenant which
         reduces the amount secured by the Letter of Credit by Three Hundred
         Thirty-Nine Thousand Eight Hundred Ninety-Three and 75/100 Dollars
         ($339,893.75) so that the remaining amount secured by the Letter of
         Credit shall be Three Hundred Thirty-Nine Thousand Eight Hundred
         Ninety-Three and 75/100 Dollars ($339,893.75) on the first day of the
         thirty-seventh (37th) month of the Lease Term if (i) Tenant is not then
         in default under the terms of this Lease without the benefit of notice
         or grace (provided that such reduction shall occur if and when Tenant
         cures the same within the applicable cure period), and (ii) Landlord
         has not applied such deposit, or any portion thereof, to Landlord's
         damages arising from any default on the part of Tenant, whether or not
         Tenant has restored the amount so applied by Landlord. For the purposes
         hereof, "liquidity" shall be measured as a total of cash, cash
         equivalents and short-term and long-term marketable securities on
         Tenant's balance sheet.

         (C) Tenant not then being in default and having performed all of its
         obligations under this Lease, including the payment of all Annual Fixed
         Rent, Landlord shall return the deposit, including all interest earned
         thereon, or so much thereof as shall not have theretofore been applied
         in accordance with the terms of this Section 8.21, to Tenant on the
         expiration or earlier termination of the term of this Lease (as the
         same may have been extended) and surrender possession of the Premises
         by Tenant to Landlord in the condition required in the Lease at such
         time.

                                       57
<PAGE>
8.22  LATE PAYMENT. If after having received written notice of late payment one
      time during any calendar year during the Lease Term, Tenant shall
      thereafter fail to make any payment or installment of Annual Fixed Rent or
      Additional Rent on or before the date (the "Interest Accrual Date") which
      is five (5) days from the date on which the same first becomes payable
      under this Lease, the amount of such payment or installment shall bear
      interest from the Interest Accrual Date through and including the date
      such payment or installment is received by Landlord, at a rate equal to
      the lesser of (i) the rate announced by Fleet National Bank (or its
      successor) from time to time as its prime or base rate (or if such rate is
      no longer available, a comparable rate reasonably selected by Landlord),
      plus two percent (2%), or (ii) the maximum applicable legal rate, if any.
      Such interest shall be deemed Additional Rent and shall be paid by Tenant
      to Landlord upon demand.

8.23  TENANT'S PAYMENTS. Each and every payment and expenditure, other than
      Annual Fixed Rent, shall be deemed to be Additional Rent hereunder,
      whether or not the provisions requiring payment of such amounts
      specifically so state, and shall be payable, unless otherwise provided in
      this Lease, within thirty (30) days after written demand by Landlord, and
      in the case of the non-payment of any such amount, Landlord shall have, in
      addition to all of its other rights and remedies, all the rights and
      remedies available to Landlord hereunder or by law in the case of
      non-payment of Annual Fixed Rent. Unless expressly otherwise provided in
      this Lease, the performance and observance by Tenant of all the terms,
      covenants and conditions of this Lease to be performed and observed by
      Tenant shall be at Tenant's sole cost and expense. If Tenant has not
      objected to any statement of Additional Rent which is rendered by Landlord
      to Tenant within ninety (90) days after Landlord has rendered the same to
      Tenant, then the same shall be deemed to be a final account between
      Landlord and Tenant not subject to any further dispute. In the event that
      Tenant shall seek Landlord's consent or approval under this Lease, then
      Tenant shall reimburse Landlord, upon demand, as Additional Rent, for all
      reasonable costs and expenses, including legal and architectural costs and
      expenses, incurred by Landlord in processing such request, whether or not
      such consent or approval shall be given.

8.24  WAIVER OF TRIAL BY JURY. To induce Landlord to enter into this Lease,
      Tenant hereby waives any right to trial by jury in any action, proceeding
      or counterclaim brought by either Landlord or Tenant on any matters
      whatsoever arising out of or any way connected with this Lease, the
      relationship of the Landlord and the Tenant, the Tenant's use or occupancy
      of the Premises and/or any claim of injury or damage, including but not
      limited to, any summary process eviction action.

8.25  GOVERNING LAW. This Lease shall be governed exclusively by the provisions
      hereof and by the law of the Commonwealth of Massachusetts, as the same
      may from time to time exist.


                                       58
<PAGE>
      EXECUTED as a sealed instrument in two or more counterparts each of which
shall be deemed to be an original.


                               LANDLORD:

WITNESS:                       STONY BROOK ASSOCIATES LLC, a
                               Delaware limited liability company
----------------------------
                               By:  Jones Road Development Associates LLC, a
                                    managing member

                                    By:  Boston Properties Limited Partnership,
                                         a managing member

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By: /s/ Michael A. Cantalupa
                                                 -------------------------------
                                              Name: Michael A. Contalupa
                                                   -----------------------------
                                              Title: Sr. Vice President
                                                    ----------------------------


                               TENANT:

                               NETEGRITY, INC.


                                    By:   /s/ Regina O. Sommer
                                         ---------------------------------------
                                    Name:
                                           -------------------------------------
                                    Title:  PRESIDENT
                                            ------------------------------------
                                            (OR VICE PRESIDENT)
                                            ------------------------------------
                                    HERETO DULY AUTHORIZED


ATTEST:


Name:                               By:  /s/ Regina O. Sommer
      ----------------------
Title: SECRETARY                    Name:
       ---------------------
       (ASSISTANT SECRETARY)        Title:  TREASURER
----------------------------                ------------------------------------
                                            (OR ASSISTANT TREASURER)
                                            ------------------------------------
                                    HERETO DULY AUTHORIZED

                                    (CORPORATE SEAL)


                                       59
<PAGE>
                                    EXHIBIT A

     Five parcels of land in Waltham and Weston, Middlesex County, Commonwealth
of Massachusetts, of which Parcel I and Parcel II are shown on a plan entitled
"Plan of Land in Waltham, Massachusetts, Prepared For Boston Properties," by
Bradford Saivetz + Associates, Inc., Engineers and Architects, Scale 1" - 80',
dated August 4, 1998, and recorded with Middlesex South Registry of Deeds as
Plan #863 of 1998 in Book 28950, Page 76; being further described as follows:

PARCEL I:

The land in Waltham shown as "Parcel One" on said plan, and being further
described as follows:

      Beginning at a stone bound on the northerly sideline of the land
      formerly of The Boston and Maine Railroad Central Mass. Div., now of
      the Massachusetts Bay Transportation Authority (MBTA) said bound being
      at the southeasterly corner of the herein described premises;

      thence running by a curve to the right having a radius of 1122.13 feet
      and an arc length of 253.63 feet;

      thence turning and running N 67(degree) 04' 17" W by land now or formerly
      of Abigail Hemenway a distance of 97.00 feet to a point;

      thence turning and running S 15(degree) 48' 39" W by land of said Hemenway
      a distance of 15.00 feet;

      thence running by said MBTA land by a curve to the right having a radius
      of 1122.13 feet and an arc length of 367.75 feet to a point;

      thence turning and running N 54(degree) 43' 37" W by said MBTA land 162.84
      feet to a point;

      thence running by said MBTA land by a curve to the left having a radius of
      1183.68 feet and an arc length of 293.42 feet to a point on a stone wall;

      thence turning and running by said wall and by land now or formerly of the
      Robinson/Waltham Company the following eight courses:

      N 16(degree) 49' 21" E, 62.97 feet;
      N 34(degree) 45' 37" E, 18.58 feet to a drill hole;
      N 51(degree) 21' 13" E, 11.21 feet;
      N 62(degree) 49' 54" E, 28.58 feet;
      N 80(degree) 23' 22" E, 13.70 feet:
      N 84(degree) 13' 51" E, 77.28 feet to a drill hole;
<PAGE>
      S 64(degree) 16' 21" E, 43.21 feet to a drill hole;
      S 35(degree) 57' 50" E, 26.95 feet.

      Thence turning and running by land now or formerly of Ethel V. Slawsby,
      land of Rob, Paul & James McGinty, Jones Road, and land of Greenwall
      Associates, S 69(degree) 49' 03" E a distance of 877.27 feet to a point;

      thence turning and running by land now or formerly of Philip Pagliazzo and
      by said MBTA land S 09(degree) 42' 43" E a distance of 203.18 feet to the
      point of beginning.

The above described parcel contains 5.25 acres, more or less, according to said
plan.

Said Parcel I is also shown as three parcels known as "Lot 17A, 121,699 +/- S.F.
(2.79 +/- AC.)," "Lot 17B, 85,950 +/- S.F. (1.97 +/- AC.)," and "Jones Road
Extension (Private) (50' Wide)" on a plan entitled "Lot Layout Plan I, Jones
Road Extension, Waltham, Massachusetts, Issued for Definitive Subdivision Plan
Approval, Drawing C-4 of 15," and prepared by Vanasse Hangen Brustlin, Inc.,
last dated revision August 12, 1998, which plan was recorded with Middlesex
South Registry of Deeds as Plan #162 of 1999, in Book 29826, Page 353.

PARCEL II:

The land in Waltham and Weston shown as "Parcel Two" on said plan, and being
further described as follows:

      Beginning at a stone bound at the southeasterly corner of the
      above-described Parcel One;

      thence running S 01(degree) 22' 22" E a distance of 82.50 feet across land
      of the MBTA to a point on the southerly layout line of said MBTA land;

      thence running by a curve to the right having a radius of 1204.63 feet and
      an arc length of 374.70 feet to the true point of beginning.

      thence turning and running S 15(degree) 48' 39" W a distance of 98.17 feet
      to a point;

      thence turning and running S 86(degree) 00' 21" E a distance of 96.94 feet
      to a point;

      thence turning and running S 24(degree) 00' 59" W, partly by a wall,
      488.49 feet to a drill hole;

      thence turning and running by a wall S 33(degree) 31' 30" W a distance of
      91.45 feet to a drill hole;


                                       2
<PAGE>
      thence turning and running by a wall N 51(degree) 00' 53" W a distance of
      49.01 feet to a drill hole;

      thence turning and running by a wall N 57(degree) 39' 25" W a distance of
      108.53 feet to a drill hole;

      thence turning and running by a wall N 53(degree) 23' 23" W a distance of
      46.45 feet to a drill hole;

      thence turning and running by a wall N 34(degree) 40' 17" W a distance of
      87.60 feet to a drill hole;

      thence turning and running by a wall N 68(degree) 31' 10" W a distance of
      143.69 feet to a drill hole;

      thence turning and running S 60(degree) 25' 39" W a distance of 70 feet
      more or less to a point in the centerline of Stony Brook;

      then turning and running by the centerline of Stony Brook, approximately
      590+/- feet to a point on the northerly side of the land formerly of The
      Boston & Maine Railroad, Fitchburg Div., now of the Massachusetts Bay
      Transportation Authority (MBTA);

      thence running by said MBTA land, by a curve to the left having a radius
      of 1959.37 feet and an arc length of 42 feet, more or less, to a point of
      compound curvature;

      thence running by said MBTA land, by a curve to the left having a radius
      of 1923.21 feet and an arc length of 212.96 feet to a point;

      thence turning and running by said MBTA land N 53(degree) 58' 14" W a
      distance of 272.68 feet to a point on the Town Line dividing the City of
      Waltham and Town of Weston;

      thence turning and running by said Town Line N 22(degree) 22' 15" E a
      distance of 52.90 feet to a point;

      thence continuing by said Town Line N 22(degree) 22' 16" E a distance of
      147.63 feet to a point on the southerly sideline of land now of the
      Massachusetts Bay Transportation Authority (MBTA) land, formerly of the
      Boston & Maine Railroad Central Mass. Division;

      thence running by said MBTA land by a curve to the right having a radius
      of 1101.18 feet and an arc length of 898.10 feet to a point;



                                       3
<PAGE>
      thence turning and running by said MBTA land S 54(degree) 43' 37" E a
      distance of 162.84 feet to a point;

      thence running by said MBTA land by a curve to the left having a radius of
      1204.63 feet and an arc length of 395.77 feet to the true point and place
      of beginning.

The above described premises contains 17.5+/- acres, according to said plan.

So much of said Parcel II as is located in Waltham is also shown as "Lot 1A,
760,126 +/- S.F. (17.5 +/- AC.)" on a plan entitled "Lot Layout Plan I, Jones
Road Extension, Waltham, Massachusetts, Issued for Definitive Subdivision Plan
Approval, Drawing C-4 of 15," and prepared by Vanasse Hangen Brustlin, Inc.,
last dated revision August 12, 1998, which plan was recorded with Middlesex
South Registry of Deeds as Plan #162 of 1999, in Book 29826, Page 353.

PARCEL III:

A parcel of land in Weston shown as "Samuel Philip Miller" on a plan entitled
"Plan of Lands in Waltham, Massachusetts" by Rowland H. Barnes & Co. - Civil
Engineers, dated May 1952, and recorded as Plan No. 2231 of 1952 in Book 8010,
Page 143.

      Said parcel is also shown on a Survey entitled "ALTA/ACSM Land Title
      Survey, Waltham/Weston Corporate Center, 50 Jones Road, Waltham,
      Massachusetts," prepared by Cubellis Saivetz Associates, Zero Campanelli
      Drive, Braintree, Mass., 02184, dated January 17, 2001, and bounded and
      described as follows:

      Beginning at a point on the northerly sideline of land formerly of the
      Boston & Maine Railroad, Fitchburg, Div., now of the Massachusetts Bay
      Transportation Authority (MBTA), at its intersection with the southerly
      sideline of land formerly of the Boston & Maine Railroad Central Mass.
      Div., now of the MBTA;

      thence running by said MBTA land by a curve to the right having a radius
      of 1101.18 feet and an arc length of 228.90 feet to a point intersecting
      said southerly line of said MBTA land and the approximate town line
      dividing the Town of Weston and the City of Waltham;

      thence turning and running S 22(degree) 22' 16" W by Parcel Two a distance
      of 147.63 feet to a point;

      thence turning and running N 67(degree) 09' 45" W by said MBTA land, in
      part by a wall, a distance of 175.59 feet to the point of beginning.



                                       4
<PAGE>
PARCEL  IV:

A parcel of land in Weston being shown as lot "5A, 0.8 acres, Alfred Jones," on
a plan entitled "Plan of Lands in Waltham, Massachusetts" by Rowland H. Barnes &
Co. - Civil Engineers, dated May 1952, and recorded as Plan No. 2231 of 1952 in
Book 8010, Page 143.

The above described parcel contains 0.8 acres, more or less, according to said
plan.

      Said parcel is also shown on a Survey entitled "ALTA/ACSM Land Title
      Survey, Waltham/Weston Corporate Center, 50 Jones Road, Waltham,
      Massachusetts," prepared by Cubellis Saivetz Associates, Zero Campanelli
      Drive, Braintree, Mass., 02184, dated January 17, 2001, and bounded and
      described as follows:

      Beginning at the southeasterly corner of the herein described premises;

      thence running by land of the MBTA by a curve to the left having a radius
      of 1959.37 feet and an arc length of 519 feet, more or less, to a point in
      the centerline of the Stony Brook;

      thence turning and running by the centerline of the Stony Brook and by
      Parcel Two a distance of 590+/- feet, more or less, to a point;

      thence running by land now or formerly of the Massachusetts Broken Stone
      Company S 60 (degree) 25' 39" W a distance of 100+/- feet, more or less,
      to the point of beginning.

PARCEL V (Easement Parcel):

Crossing Easement from Massachusetts Bay Transportation Authority as recited in
Easement Agreement dated February 11, 1999, recorded February 22, 1999, in Book
29826, Page 393, and shown on Easement Plan recorded as Plan #163 of 1999, in
Book 29826, Page 392; also shown as "Crossing Easement A" over land in Waltham
on a plan entitled "Lot Layout Plan I, Jones Road Extension, Waltham,
Massachusetts, Issued for Definitive Subdivision Plan Approval, Drawing C-4 of
15," and prepared by Vanasse Hangen Brustlin, Inc., last dated revision August
12, 1998, which plan was recorded with Middlesex South Registry of Deeds as Plan
#162 of 1999, in Book 29826, Page 353.


                                       5
<PAGE>
                                    EXHIBIT B

                         WALTHAM WESTON CORPORATE CENTER
                                 NETEGRITY, INC.
                  BUILDING STANDARD MATERIALS AND TURNKEY SCOPE

Landlord will provide a turn-key buildout of Tenant's Premises substantially in
accordance with the following scope definition and plan dated 7/30/02 attached
hereto and incorporated herein as part of this Exhibit B. The improvements will
be constructed with the building standard materials described below.

PARTITIONS

The following building standard materials will be provided by Landlord:

      a.    Interior ceiling partitions (i.e. partitions within a single
            premises) will be 2-1/2" metals studs 24" on center with one layer
            of 5/8" gypsum board on each side. Partition will extend from floor
            to six (6) inches above the acoustic tile ceiling.

      b.    Demising or other partitions providing sound attenuation will be
            2-1/2" metal studs with two layers of 5/8" gypsum board on one side
            and one layer of 5/8" gypsum board on the other. Demising partitions
            will extend from floor to underside of structure above, subject to
            requirements of the building air conditioning system, and the
            partition will be filled with 3" compressed fiberglass sound
            insulation.

      c.    All partitions will have vinyl base 4" high.

      d.    The CEO office, CEO's Assistant Area and the office next to the Engr
            Kitchen and Play Area to receive demising partitions described in b.
            above. Additional sound attenuation materials to be evaluated by the
            architect.

The following turnkey scope will be provided by Landlord:

      a.    Ceiling high partitions will be provided for the following:

            1.    Twenty-two (22) offices - 100 SF

            2.    Fourteen (14) offices - 120 SF

            3.    Fourteen (14) offices - 150 SF

            4.    Six (6) offices - 175 SF

            5.    Two (2) offices - 200 SF

            6.    One (1) Large Conference Room - 400 SF

            7.    Six (6) Medium Conference Room - 300 SF

            8.    Three (3) Small Conference Room - 140 SF

            9.    One (1) Large Lab - 670 SF

            10.   Three (3) Medium Labs - Two (2) at 300 SF and One (1) at 400
                  SF

            11.   One (1) Large Server Room - 720 SF

            12.   One (1) Engr Kitchen & Play Area

            13.   One (1) Shipping & Receiving Area


Netegrity, Inc. - Exhibit B                                                    1
<PAGE>
            14.   One (1) Service Lobby

            15.   Four (4) Small Storage Closets

            16.   Four (4) Small Telephone Closets

            17.   One (1) Break Area

            18.   One (1) Lunch/Vending Area

            19.   One (1) Kitchen Area

            20.   One (1) Toilet Room

            21.   One (1) Travel Office

      b.    Glass sidelights (18") shall be provided at all office and
            conference room doors 100 SF and larger (68 total)

DOORS

Building standard doors shall consist of the following:

      a.    All doors within a single premises will be 3'0" x 8'0" solid core
            with stain grade, standard veneer faces, 1-3/4" thick and shall
            receive two coats of factory clear polyurethane finish. Door frames
            will be aluminum. Hardware will include 2 pair of butts, one
            standard duty latch set and one door stop. Offices greater than 175
            SF shall be equipped with locksets (9 total).

      b.    All office doors to contain one coat hook.

      c.    Lab, Server Room, and Playroom doors to have closers (11 total).

      d.    The four (4) doors located off the main reception area and two (2)
            doors in the East Wing Service Lobby shall have vision panels.

      e.    Glass sidelights - frames will be aluminum with 18" single pane
            glazing.

      f.    Perimeter office sidelights shall have a glazing film applied (23
            total).

PAINTING AND WALL COVERING

The building standard for painting and wall covering is:

      a.    All wall surfaces shall receive two coats of eggshell finish latex
            paint. Color selection will be made from a mutually agreed upon
            color palette with not more than one color per office. Accent colors
            may be used throughout the Premises.

      b.    Conference rooms and senior VP office (175 SF or larger) may contain
            one accent color per room.

      c.    All door frames within a single premises shall receive two coats of
            semi-gloss enamel to be selected from building standard samples. All
            interior door frames shall receive two coats of clear polyurethane.

CEILING

Building standard ceilings shall be 2'0" x 2'0" reveal edge textured acoustic
lay-in tile, Celotex LeBaron, or equal. Ceiling height will be 9'0" typically.
Above building standard ceiling will be provided in the following areas:

      a.    Reception Area - Per mutually agreed to perspective drawing dated
            August 8, 2002, a combination drywall ceiling (approximately 50%)
            and


Netegrity, Inc. - Exhibit B                                                    2
<PAGE>
            upgraded 2'0" x 2'0" acoustic tile (approximately 50%; target
            $3.25/sf) will be provided.

      b.    Medium Conference Room - Per mutually agreed to perspective drawing
            dated August 8, 2002, a combination drywall ceiling (approximately
            50%) and upgraded 2'0" x 2'0" acoustic tile (approximately 50%;
            target $3.25/sf) will be provided.

      c.    Large Conference Room - A combination of drywall and upgraded 2'0" x
            2'0" acoustic tile (target $3.25/sf) will be provided. Target
            percentage of drywall and acoustic tile is 25% and 75%,
            respectively.

      d.    Engr Lunch and Playroom - A drywall soffit will be installed above
            the counters on the east side of the Play Room (22 LF).

      e.    Intersection points - upgraded ceiling treatment (drywall or dropped
            2' x 2' acoustic tile) to be evaluated by architect, tenant and
            landlord at various corridor intersection points (6 locations
            total).

LIGHTING

Building standard lighting shall be 2' x 4', low-brightness three tube parabolic
reflector fixtures. Above building standard lighting shall be provided in the
following areas:

      a.    Reception Area - Incandescent downlight fixtures shall be installed
            in the Reception Area (approximately 14 fixtures). In addition, one
            standard drop fixture to be located over the seating area.

      b.    Medium Conference Room - Incandescent downlight fixtures shall be
            installed in the Medium Conference Room (approximately 10 fixtures).
            In addition, one standard drop fixture to be located over the
            conference table.

      c.    Large Conference Room - Incandescent downlight fixtures to be
            installed in the Large Conference Room (approximately 14 fixtures).

      d.    Open office areas - Indirect lighting to be installed in the open
            office areas.

      e.    Private offices - tenant will determine whether to install building
            standard 2' x 4' fixtures or indirect lighting in partitioned
            offices. For offices 120 SF or smaller, a 6' indirect fixture will
            be provided. For offices larger than 120 SF, a 8' indirect fixture
            will be provided.

TELEPHONE OUTLETS

Building standard tel/data work shall include one wall location per office
prepared to receive a telephone outlet installation by Tenant's
telecommunication contractor. In total, one tel/data box will be provided for
each 200 square feet of rentable area, each to consist of plaster ring and cable
pull string to above its individual ceiling. In addition, each conference room
shall have two tel/data boxes on opposite walls.

ELECTRIC

The following describes building standard materials and turnkey scope for
Tenant's electrical:

      a.    Two (2) electric outlets (one of which may be a quadplex outlet) and
            one (1) telephone outlet per office, except all conference rooms to
            have four


Netegrity, Inc. - Exhibit B                                                    3
<PAGE>
            (4) electric duplex outlets and two (2) telephone outlets. Eight (8)
            duplex outlets per circuit.

      b.    Power feeds to two hundred forty-eight (248) workstations, four (4)
            workstations per circuit.

      c.    Tenant to provide data and telephone wiring to offices and
            workstations.

      d.    Miscellaneous duplex outlets, as reasonably required, in all
            auxiliary space such as lichens, mail room, printer/fax locations
            and copy rooms with the exception of special electrical requirements
            in excess of the criteria specified in Exhibit C Landlord Services.

HVAC

The building standard HVAC scope consists of a complete variable air volume
(VAV) system installed to serve all areas of the premises, including the
installation of a medium pressure ring duct, as provided in the preliminary Base
Building Outline Specifications previously furnished. Space thermostats and
separate zones will be provided for approximately each 50 lineal feet of
building perimeter and approximately each 2,000 square feet of building
interior. Any thermostats located at an exterior wall shall be insulated.

Supply air shall be provided through ceiling mounted diffusers. Return air will
be into a ceiling return air plenum through slots in the light fixtures or
separate ceiling mounted grills as required. A separate zone and exhaust fan to
the ceiling plenum for the conference rooms.

MILLWORK

      a.    Plastic laminate base cabinets and counter tops in:

            i)    Copy Rooms, 25 LF

            ii)   Break Rooms/Kitchens, 52 LF

            iii)  Fax/Printer locations, 35 LF

      b.    Paint grade shelf and rod in each Coat Closet (2 total).

PLUMBING

One (1) sink with waste and hot and cold water in Engr Lunch & Play Area, Break
Room, East Wing Kitchen and restroom located near the Reception Area. In
addition a coffee maker hook up will be provided in the in Engr Lunch & Play
Area, Break Room and East Wing Kitchen. One (1) toilet will be provided in the
restroom located near the Reception Area. Any additional plumbing required to be
provided at Tenant's Cost.

FLOOR FINISHES

A flooring allowance of $20/SY of installed area shall be provided (including
vinyl base at partitions).



Netegrity, Inc. - Exhibit B                                                    4
<PAGE>
STRUCTURAL REINFORCEMENT

No additional structural requirements beyond that provided by Base Building
Specifications are included in tenant improvements.

FIRE PROTECTION

The fire protection system will be installed to meet all applicable local, state
and federal codes and regulations for light hazard occupancy.

SPECIAL ALLOWANCE

Landlord will provide a Special Allowance of $30,000 to be used by Tenant in
connection with Tenant Improvements to the Premises above and beyond the turnkey
scope described above.

Except as described above, the following work is excluded from the Landlord's
turnkey scope of work:

      a.    Any electrical work in excess of that described in the preliminary
            Base Building Outline Specifications previously furnished.

      b.    Any HVAC work in excess of that described in the preliminary Base
            Building Outline Specifications previously furnished.

      c.    Tenant's telecommunication design, systems, wires, equipment and
            other services or infrastructure required by Tenant.

      d.    Tenant's security design, systems, equipment, wires and other
            services and infrastructure required by Tenant.

      e.    Tenant's audio/visual design, systems, equipment and other services
            and infrastructure required by Tenant.

      f.    Tenant's furniture design, wiring, and installation.




Netegrity, Inc. - Exhibit B                                                    5
<PAGE>
                                   EXHIBIT B-1

                         WALTHAM WESTON CORPORATE CENTER
                   ADDITIONAL TENANT WORK DRAWING REQUIREMENTS

1.    Floor plan indicating workstation and furniture locations.

2.    Location of standard electrical convenience outlets and telephone
      outlets.

3.    Location and details of special electrical outlets; (e.g. Xerox),
      including voltage, amperage, phase and NEMA configuration of outlets.

4.    Locations and details of special security requirements and equipment.

5.    Locations and details of special audio/visual requirements, equipment
      and systems.

6.    Location and heat load in BTU/Hr. of all special air conditioning and
      ventilating requirements (i.e. rooms such as telephone closets, server
      room, NOC rooms and labs).

7.    Location and details of special structural requirements, e.g., slab
      penetrations and areas with floor loadings exceeding a live load of 100
      lbs./s.f (i.e. for any UPS system, heavy file storage, etc)

8.    Details and specifications of special millwork, rolling doors/movevable
      partitions, grilles, blackboards, shelves, etc.

9.    Verified dimensions of all built-in equipment (file cabinets, lockers,
      plan files, etc.).

10.   Location of any special soundproofing requirements.

11.   All drawings to be uniform size (30" X 42") and shall incorporate the
      standard project electrical and plumbing symbols and be at a scale of 1/8"
      = 1' or larger.

12.   Additional Tenant Work Drawing submittal shall be in a CAD format
      compatible with Landlord's architect drawing system.
<PAGE>
                                    EXHIBIT C

                         WALTHAM WESTON CORPORATE CENTER
                             WALTHAM, MASSACHUSETTS

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

I.    CLEANING:

      Cleaning and janitor services as provided below:

      A.    OFFICE AREAS:

            DAILY: (Monday through Friday, inclusive, holidays excepted).

            1.    Empty and clean all waste receptacles and ashtrays and remove
                  waste material from the Premises; wash receptacles as
                  necessary.

            2.    Sweep and dust mop all uncarpeted areas using a dust-treated
                  mop.

            3.    Vacuum all rugs and carpeted areas.

            4.    Hand dust and wipe clean with treated cloths all horizontal
                  surfaces, including furniture, office equipment, window sills,
                  door ledges, chair rails, and convector tops, within normal
                  reach.

            5.    Wash clean all water fountains and sanitize.

            6.    Move and dust under all desk equipment and telephones and
                  replace same (but not computer terminals, specialized
                  equipment or other materials).

            7.    Wipe clean all chrome and other bright work.

            8.    Hand dust grill work within normal reach.

            9.    Main doors to premises shall be locked and lights shut off
                  upon completion of cleaning.

            10.   Empty all recycling bins and remove all recyclables.

            WEEKLY:

            Dust coat racks and the like.
<PAGE>
            QUARTERLY:

            1.    Render high dusting not reached in daily cleaning to
                  include:

                  a)    dusting all pictures, frames, charts, graphs and similar
                        wall hangings.

                  b)    dusting of all vertical surfaces, such as walls,
                        partitions, doors and door frames, etc.

                  c)    dusting all pipes, ducts and moldings.

                  d)    dusting of all vertical blinds.

            2.    Spray buff all resilient floors.

      B.    LAVATORIES:

            DAILY: (Monday through Friday, inclusive, holidays excepted).

            1.    Sweep and damp mop.

            2.    Clean all mirrors, powder shelves, dispensers and receptacles,
                  bright work, flushometers, piping and toilet seat hinges.

            3.    Wash both sides of all toilet seats.

            4.    Wash all basins, bowls and urinals.

            5.    Dust and clean all powder room fixtures.

            6.    Empty and clean paper towel and sanitary disposal receptacles.

            7.    Remove waste paper and refuse.

            8.    Refill tissue holders, soap dispensers, towel dispensers,
                  sanitary dispensers; materials to be furnished by Landlord.
<PAGE>
            MONTHLY:

            1.    Machine scrub lavatory floors.

            2.    Wash all partitions and tile walls in lavatories.

            3.    Dust all lighting fixtures and grills in lavatories.

      C.    MAIN LOBBIES, ELEVATORS, STAIRWELLS AND COMMON CORRIDORS:

            DAILY: (Monday through Friday, inclusive, holidays excepted).

            1.    Sweep and damp mop all floors, empty and clean waste
                  receptacles, dispose of waste.

            2.    Clean elevators, wash or vacuum floors, wipe down walls and
                  doors.

            3.    Spot clean any metal work inside lobbies.

            4.    Spot clean any metal work surrounding building entrance doors.

            5.    Sweep all stairwells and dust handrails.

            MONTHLY:

            1.    All resilient tile floors in public areas to be spray buffed.

      D.    WINDOW CLEANING:

            All exterior windows shall be washed on the inside and outside
            surfaces no less than two (2) times per year.

II.   HVAC:

      A.    Heating, ventilating and air conditioning equipment will be provided
            with sufficient capacity to accommodate a maximum population density
            of one (1) person per one hundred fifty (150) square feet of
            rentable floor area served, and a combined lighting and standard
            electrical load of 4 watts per square foot of rentable floor area.
            In the event Tenant introduces into the Premises personnel or
            equipment which overloads the system's ability to adequately perform
            its proper functions, Landlord shall so notify Tenant in writing. If
            within fifteen (15) days Tenant has not modified its use so as not
            to cause such overload, Landlord may, if needed, provide
            supplemental systems at Tenant's expense.
<PAGE>
            Operating criteria of the basic system are in accordance with the
            Massachusetts Energy Code and shall not be less than the following:

            i)    Cooling season indoor conditions of not in excess of 78E
                  Fahrenheit when outdoor conditions are 88E Fahrenheit drybulb
                  and 74E Fahrenheit wetbulb.

            ii)   Heating season minimum room temperature of 72E Fahrenheit when
                  outdoor conditions are 1E Fahrenheit drybulb.

      B.    Landlord shall provide heating, ventilating and air conditioning as
            normal seasonal charges may require during Normal Building Operating
            Hours (7:00 a.m. to 6:00 p.m., Monday through Friday, and 8:00 a.m.
            to 1:00 p.m. on Saturdays, legal holidays in all cases excepted).

            If Tenant shall require air conditioning (during the air
            conditioning season) or heating or ventilating during any season
            outside Normal Building Operating Hours, Landlord shall use
            landlord's best efforts to furnish such services for the area or
            areas specified by written request of Tenant delivered to the
            Building Superintendent or the Landlord before 3:00 p.m. of the
            business day preceding the extra usage. For such services, Tenant
            shall pay Landlord, as additional rent, upon receipt of billing, a
            sum equal to the cost incurred by Landlord.

III.  ELECTRICAL SERVICES:

      A.    Landlord shall provide electric power for a combined load of 4.0
            watts per square foot of useable area for lighting and for office
            machines through standard receptacles for the typical office space.

      B.    Landlord, at its option, may require separate metering and direct
            billing to Tenant for the electric power required for any special
            equipment (such as computers and reproduction equipment) that
            requires either 3-phase electric power or any voltage other than
            120, or for any other usage in excess of 3.5 watts per square foot.

      C.    Landlord will furnish and install, at Tenant's expense, all
            replacement lighting tubes, lamps and ballasts required by Tenant.
            Landlord will clean lighting fixtures on a regularly scheduled basis
            at Tenant's expense.

IV.   ELEVATORS:

      Provide passenger elevator service twenty-four (24) hours per day, seven
      (7) days per week.
<PAGE>
V.    WATER:

      Provide hot water for lavatory purposes and cold water for drinking,
      lavatory and toilet purposes.

VI.   BUILDING DIRECTORY

      Provide a building directory.

VII.  CARD ACCESS SYSTEM:

      Landlord will provide a card access system at one entry door of the
      building.
<PAGE>
                                    EXHIBIT E

               DECLARATION AFFIXING THE COMMENCEMENT DATE OF LEASE

      THIS AGREEMENT made this      day of            , 200 , by and between
STONY BROOK ASSOCIATES LLC (hereinafter "Landlord") and NETEGRITY, INC.
(hereinafter "Tenant").

                          W I T N E S S E T H T H A T:

      1.    This Agreement is made pursuant to Section 2.4 of that certain Lease
dated                , 2002 between the parties aforenamed as Landlord and
Tenant (the "Lease").

      2.    It is hereby stipulated that the Lease Term commenced on       ,
(being the "Commencement Date" under the Lease), and shall end and expire on
        , unless sooner terminated or extended, as provided for in the Lease.

      WITNESS the execution hereof under seal by persons hereunto duly
authorized, the date first above written.

                              LANDLORD:

                              STONY BROOK ASSOCIATES LLC

                              By:   Jones Road Development Associates
                                    LLC, a managing member

                                    By:   Boston Properties Limited Partnership,
                                          a managing member

                                          By:   Boston Properties, Inc., its
                                                general Partner

                                                By:
                                                   ---------------------------
                                                Name:
                                                     -------------------------
                                                Title:
                                                      ------------------------

                              TENANT:

                              NETEGRITY, INC.


                              By:
                                 -------------------------------
                              Name:
                                   -----------------------------
                              Title:
                                    ----------------------------
<PAGE>
                          COMMONWEALTH OF MASSACHUSETTS

COUNTY OF SUFFOLK                                                 , 200
                                                  ----------------     -


      Then personally appeared before me the above-named                , as
                                                         ---------------
              of Stony Brook Associates LLC as aforesaid, who acknowledged the
-------------
foregoing instrument to be his free act and deed as such officer and the free
act and deed of said limited liability company.


                                          NOTARY PUBLIC
                                          My Commission Expires:



                          COMMONWEALTH OF MASSACHUSETTS

COUNTY OF                                                             , 200
          ---------------------------              -------------------     -


      Then personally appeared before me the above-named                 , as
                                                         ---------------
                   of Netegrity, Inc. as aforesaid, who acknowledged the
------------------
foregoing instrument to be his/her free act and deed as such officer and the
free act and deed of said corporation.


                                          NOTARY PUBLIC
                                          My Commission Expires:



                                      -2-
<PAGE>
                                    EXHIBIT F

                 BROKER DETERMINATION OF PREVAILING MARKET RENT
                     AND OTHER BUSINESS TERMS AND CONDITIONS

      Where in the Lease to which this Exhibit is attached provision is made for
a Broker Determination of Prevailing Market Rent and/or the other business terms
and conditions upon which particular space is to be leased by Tenant, the
following procedures and requirements shall apply:

1.    Tenant's Request. Tenant shall send a notice to Landlord by the time set
      for such notice in the applicable section of the Lease, requesting a
      Broker Determination of the Prevailing Market Rent and (to the extent
      applicable) other business terms and conditions, which notice to be
      effective must (i) make explicit reference to the Lease and to the
      specific section of the Lease pursuant to which said request is being
      made, (ii) include the name of a broker selected by Tenant to act for
      Tenant, which broker shall have at least ten (10) years experience dealing
      in properties of a nature and type generally similar to the Building
      located in the Boston West Suburban Market, and (iii) explicitly state
      that Landlord is required to notify Tenant within thirty (30) days of an
      additional broker selected by Landlord.

2.    Landlord's Response. Within thirty (30) days after Landlord's receipt of
      Tenant's notice requesting the Broker Determination and stating the name
      of the broker selected by Tenant, Landlord shall give written notice to
      Tenant of Landlord's selection of a broker having at least the affiliation
      and experience referred to above.

3.    Selection of Third Broker. Within ten (10) days thereafter the two (2)
      brokers so selected shall select a third such broker also having at least
      the affiliation and experience referred to above.

4.    Broker Determination. Within thirty (30) days after the selection of the
      third broker, the three (3) brokers so selected, by majority opinion,
      shall make a determination of the annual fair market rental value of the
      Premises and (to the extent applicable) other business terms and
      conditions for the period referred to in the Lease. Such determination (x)
      may include provision for annual increases or decreases in rent during
      said term if so determined, (y) shall take into account the condition of
      the Premises and (z) shall take account of, and be expressed in relation
      to, provisions for paying for operating expenses, taxes and tenant
      electricity as contained in the Lease. The brokers shall advise Landlord
      and Tenant in writing by the expiration of said thirty (30) day period of
      the annual fair market rental value (which as so determined shall be
      referred to as the Prevailing Market


                            Exhibit F - Page 1 of 2
<PAGE>
      Rent) and (to the extent applicable) other business terms and conditions
      upon which the space is to be leased by Tenant.

5.    Resolution of Broker Deadlock. If the Brokers are unable to agree at least
      by majority on a determination of annual fair market rental value and/or
      other business terms and conditions, then the brokers shall send a notice
      to Landlord and Tenant by the end of the thirty (30) day period for making
      said determination setting forth their individual determinations, and in
      the case of monetary determinations, the highest such determination and
      the lowest such determination shall be disregarded and the remaining
      determination shall be deemed to be the determination of the monetary term
      or provision at issue.

6.    Costs. Each party shall pay the costs and expenses of the broker selected
      by it and each shall pay one half (1/2) of the costs and expenses of the
      Third Broker.

7.    Failure to Select Broker or Failure of Broker to Serve. If Tenant shall
      have requested a Broker Determination and Landlord shall not have
      designated a broker within the time period provided therefor above, then
      Tenant's Broker shall alone make the determination of Prevailing Market
      Rent and (to the extent applicable) other business terms and conditions in
      writing to Landlord and Tenant within thirty (30) days after the
      expiration of Landlord's right to designate a broker hereunder. If Tenant
      and Landlord have both designated brokers but the two brokers so
      designated do not, within a period of fifteen (15) days after the
      appointment of the second broker, agree upon and designate the Third
      Broker willing so to act, the Tenant, the Landlord or either broker
      previously designated may request the Boston Bar Association to designate
      the Third Broker willing so to act and a broker so appointed shall, for
      all purposes, have the same standing and powers as though he had been
      seasonably appointed by the brokers first appointed. In case of the
      inability or refusal to serve of any person designated as a broker, or in
      case any broker for any reason ceases to be such, a broker to fill such
      vacancy shall be appointed by the Tenant, the Landlord, the brokers first
      appointed or the said Boston Bar Association, as the case may be,
      whichever made the original appointment, or if the person who made the
      original appointment fails to fill such vacancy, upon application of any
      broker who continues to act or by the Landlord or Tenant such vacancy may
      be filled by the said Boston Bar Association, and any broker so appointed
      to fill such vacancy shall have the same standing and powers as though
      originally appointed.



                            Exhibit F - Page 2 of 2
<PAGE>
                                    EXHIBIT G

                                 NOTICE OF LEASE

Notice is hereby given pursuant to Chapter 183, Section 4, of the Massachusetts
General Laws of the following Lease:

Landlord:

      Stony Brook Associates LLC, a Delaware limited liability company

Tenant:

      Netegrity, Inc, a Delaware corporation

Date of Execution of Lease:

      August   , 2002

Description of Lease Premises:

      The entire fifth (5th) floor comprising approximately 54,383 square feet
(the "Premises"), of the building located at 201 Jones Road, Waltham,
Massachusetts (the "Building"), situated on the land more particularly described
in Exhibit A attached hereto and incorporated herein.

Term:

      The term of the Lease shall be a period of sixty (60) months commencing on
the Commencement Date.

Commencement Date:

      The first to occur of (a) the day on which the work described in Section
3.1 of the Lease to be performed by Landlord is substantially completed or (b)
the date on which Tenant commences beneficial use of the Premises or any portion
thereof.

Extension Option:

      Tenant has the option to extend the term of the Lease for one (1) period
of sixty (60) months as provided in Section 8.20 of the Lease.


                                      -1-
<PAGE>
Expansion Option:

      Tenant has the right to lease (i) an additional 5,000-10,000 square feet
located on the either the first, second, third or fourth floor of the Building
upon the terms and subject to the conditions in Section 2.1.1(A) of the Lease
and (ii) an additional 10,000-25,000 square feet located on either the first,
second, third or fourth floor of the Building upon the terms and subject to the
conditions in Section 2.1.1(B) of the Lease.

Right of First Offer:

      Tenant has the right to lease portions of the fourth floor of the Building
subject to the availability of the same and subject to the terms and conditions
set forth in Section 2.1.2 of the Lease.

      Executed as an instrument under seal as of the    day of           , 2002.

                                    STONY BROOK ASSOCIATES LLC

                                    By:   Jones Road Development Associates LLC,
                                          a managing member

                                          By:   Boston Properties Limited
                                                Partnership, a managing member

                                                By:   Boston Properties, Inc.,
                                                      its general partner

                                                By:
                                                   -------------------------
                                                Name:
                                                     -----------------------
                                                Title:
                                                      ----------------------



                                    NETEGRITY, INC.


                                    By:
                                       -------------------------------
                                    Name:
                                         -----------------------------
                                    Title:
                                          ----------------------------



                                      -2-
<PAGE>
                          COMMONWEALTH OF MASSACHUSETTS

                  , ss:                                                , 2002
------------------                                    -----------------

      Then personally appeared the above-named                     , as
                     of Boston Properties, Inc., who acknowledged the foregoing
instrument to be his free act and deed as such officer as aforesaid and the free
act and deed of said corporation as the general partner of Boston Properties
Limited Partnership as managing member of Jones Road Development Associates LLC
as managing member of Stony Brook Associates LLC, before me,


                                          ----------------------------------
                                          Notary Public
                                          My Commission Expires:





                          COMMONWEALTH OF MASSACHUSETTS

                  , ss:                                                , 2002
------------------                                    -----------------

      Then personally appeared the above-named                   , as
                  of Netegrity, Inc., who acknowledged the foregoing instrument
to be his/her free act and deed as such officer as aforesaid and the free act
and deed of said corporation, before me,


                                          ----------------------------------
                                          Notary Public
                                          My Commission Expires



                                      -3-