<PAGE>
                                                                   EXHIBIT 10.11

                                LEASE AGREEMENT

                                By and Between

                               WALTHAM 60/10 LLC

                                   Landlord

                                      And

                          RENAISSANCE WORLDWIDE, INC.

                                    Tenant



                              as of June 30, 1998
<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------

                                                                            PAGE
                                                                            ----
ARTICLE 1 DEFINITIONS AND EXHIBITS
   Section 1.1     Definitions..............................................  1
   Section 1.2     Exhibits.................................................  8
 
ARTICLE 2 DEMISE AND TERM
   Section 2.1     Premises.................................................  8
   Section 2.2     Term.....................................................  8
   Section 2.3     Extension Option.........................................  8
   Section 2.4     Right of First Offer to Purchase......................... 11
 
ARTICLE 3 CONSTRUCTION; DELIVERY AND ACCEPTANCE OF PREMISES
   Section 3.1     Landlord's Construction Obligations...................... 14
   Section 3.2     Delivery................................................. 14
   Section 3.3     Operating Costs After Tender of Possession but Prior
                   to Rent Commencement Date................................ 17
   Section 3.4     Punch Lists.............................................. 17
   Section 3.5     Representatives.......................................... 17
   Section 3.6     Base Building Plans...................................... 18
   Section 3.7     Base Building Construction............................... 18
   Section 3.8     Change Orders............................................ 18
   Section 3.9     No Interference with Landlord's Work..................... 19
   Section 3.10    Adjustments Upon Completion.............................. 19
 
ARTICLE 4 RENT
   Section 4.1     Base Rent................................................ 20
   Section 4.2     Operating Costs.......................................... 20
   Section 4.3     Allocation of Taxes...................................... 23
   Section 4.4     Parking Facility......................................... 24
   Section 4.5     Right to Audit........................................... 25
 
ARTICLE 5 MAINTENANCE AND SERVICES
   Section 5.1     Services Provided by Landlord............................ 25
   Section 5.2     Tenant's Maintenance Responsibilities.................... 27
   Section 5.3     Inspection............................................... 27
   Section 5.4     Utilities................................................ 27
   Section 5.5     Interruption of Services................................. 28
 

                                      -i-
<PAGE>
 
ARTICLE 6 ALTERATIONS AND IMPROVEMENTS
   Section 6.1     Procedures for Tenant's Improvements..................... 28
   Section 6.2     Freedom From Liens....................................... 29
   Section 6.3     Alterations are Part of the Premises..................... 29
 
ARTICLE 7 INSURANCE
   Section 7.1     Landlord's Insurance..................................... 30
   Section 7.2     Tenant's Insurance....................................... 31
   Section 7.3     General Insurance Requirements........................... 32
   Section 7.4     Waivers.................................................. 32
   Section 7.5     Landlord's Indemnification............................... 33
   Section 7.6     Tenant's Indemnification................................. 33
 
ARTICLE 8 CERTAIN RIGHTS RESERVED BY LANDLORD
   Section 8.1     Rights Reserved by Landlord.............................. 33
   Section 8.2     Emergency Entry.......................................... 34
   Section 8.3     Exhibition of Premises................................... 34
 
ARTICLE 9 ASSIGNMENT AND SUBLETTING
   Section 9.1     Assignment and Subletting................................ 34
   Section 9.2     Massachusetts General Sublease........................... 37
 
ARTICLE 10 DAMAGE BY FIRE OR OTHER CASUALTY
   Section 10.1    Termination Options...................................... 38
   Section 10.2    Repair Obligations....................................... 38
   Section 10.3    Rent Abatement........................................... 39
 
ARTICLE 11 EMINENT DOMAIN
   Section 11.1    Termination.............................................. 39
   Section 11.2    Award; Restoration....................................... 39
 
ARTICLE 12 SURRENDER OF PREMISES
   Section 12.1    Surrender of Possession.................................. 40
   Section 12.2    Holding Over............................................. 40
 

                                      -ii-
<PAGE>
 
ARTICLE 13  QUIET ENJOYMENT
   Section 13.1    Quiet Enjoyment .........................................  40
 
ARTICLE 14  DEFAULT AND REMEDIES
   Section 14.1    Events of Default........................................  40
   Section 14.2    Remedies.................................................  41
   Section 14.3    Landlord's Default.......................................  43
   Section 14.4    Legal Costs..............................................  44
 
ARTICLE 15  SUBORDINATION
   Section 15.1    Mortgages................................................  45
   Section 15.2    Attornment...............................................  45
   Section 15.3    Tenant's Notice of Default...............................  45
   Section 15.4    Estoppel Certificates....................................  45
 
ARTICLE 16  USE AND COMPLIANCE
   Section 16.1    Permitted Use............................................  47
   Section 16.2    Compliance with Laws and Recorded Covenants..............  47
   Section 16.3    Landlord's Covenants.....................................  47
   Section 16.4    Tenant's Covenants.......................................  48
 
ARTICLE 17  CAFETERIA
   Section 17.1    Cafeteria................................................  49
 
ARTICLE 18  FITNESS SPACE
   Section 18.1    Fitness Space............................................  50
 
ARTICLE 19  TENANT'S SIGNAGE

ARTICLE 20 ARBITRATION
   Section 20.1    Arbitration..............................................  52
 
ARTICLE 21  MISCELLANEOUS
   Section 21.1    Personal Property Taxes..................................  53
   Section 21.2    Notices..................................................  53
   Section 21.3    Interpretation...........................................  54
   Section 21.4    Successors and Assigns...................................  54
  

                                     -iii-
<PAGE>
 
   Section 21.5    Captions.................................................  54
   Section 21.6    Amendments...............................................  54
   Section 21.7    Survival.................................................  54
   Section 21.8    Severability.............................................  55
   Section 21.9    Brokerage................................................  55
   Section 21.10   Record Memorandum of Lease...............................  55

   EXHIBITS

   Exhibit A      Legal Description
   Exhibit B      Preliminary Plans
   Exhibit C      Work Letter
   Exhibit D      Janitorial Standards
   Exhibit E      Existing Encumbrances
   Exhibit F      MGP Sublease Requirements
 
 

                                      -iv-
<PAGE>
 
                                LEASE AGREEMENT
                                ---------------


     THIS LEASE AGREEMENT (the "Lease") is made as of the 30/th/ day of June,
1998, by and between WALTHAM 60/10 LLC, a Minnesota limited liability company
("Landlord") and RENAISSANCE WORLDWIDE, INC., a Massachusetts corporation
("Tenant").

                                   RECITALS:

     WHEREAS, Landlord and Tenant desire to memorialize their agreement
concerning the leasing by Tenant from Landlord approximately 200,000 rentable
square feet in a building to be constructed by Landlord.

     NOW, THEREFORE, in consideration of the foregoing and for other valuable
consideration, the receipt and sufficiency of which is hereby acknowledged, the
parties agree as follows:

                                   ARTICLE 1
                           DEFINITIONS AND EXHIBITS

     Section 1.1   Definitions.  In this Lease, the following defined terms
have the meanings set forth for them below or in the section of this Lease
indicated below:

          "ADA" means the Americans with Disabilities Act, as amended from time
     to time.

          "Additional Rent" means all amounts required to be paid by Tenant
     under this Lease in addition to Base Rent including, without limitation,
     Operating Expenses and Taxes.

          "Affiliate" means, with respect to any party, any entities or
     individuals that control, are controlled by or are under common control
     with such party, together with its and their respective partners,
     venturers, directors, officers, shareholders, trustees, trustors,
     beneficiaries, agents, employees and spouses.

          "Arbitration" has the meaning set forth in Article 20.

          "Base Building" means those portions of the Building and the
     associated site improvements on the Land (such as driveways, parking areas,
     landscaping and exterior lighting) that are specified on the Preliminary
     Plans, as the same may be modified by, or more particularly specified on
     the Base Building Plans in accordance with this Lease.

          "Base Building Plans" means Base Building Construction Documents
     delivered to Tenant on June 22, 1998 for the Base Building.

          "Base Rent" means the Rent payable according to Section 4.1 based on a
     rate per square foot of Rentable Area of the Premises applicable during
     each Lease Year of the Term as follows:
<PAGE>
 
                                      Rate of Base Rent Per Square 
               Lease Year(s)          Foot of Rentable Area Per Year   
               -------------          ------------------------------

                  1-5                            $21.00
                  6-10                           $23.00

          "Building" means the building to be known as and numbered 52 Second
     Avenue, which building is to be constructed by Landlord for Tenant upon the
     Land according to Article 3, and to initially contain approximately 200,000
     square feet of Rentable Area, subject to measurement pursuant to Section
     3.10, including the Parking Facility.

          "Cafeteria Space" has the meaning set forth in Section 17.1.

          "Change Order" has the meaning set forth in Section 3.8.

          "Commencement Date" means the date Landlord tenders possession of the
     Premises to Tenant with the Landlord's Work Substantially Completed
     pursuant to Section 3.2.(b).

          "Common Area" has the meaning set forth in Section 5.1.

          "Environmental Laws" means the Resource Conservation and Recovery Act,
     42 U.S.C. Section 6901 et seq., the Comprehensive Environmental Response,
                            -- ---                                            
     Compensation and Liability Act, U.S.C. Section 9601 et seq.  (including the
                                                         -- ---                 
     so-called "Superfund" amendments thereto), any other applicable Laws
     governing or pertaining to any hazardous substances, hazardous wastes,
     chemicals or other materials, including, without limitation, asbestos,
     polychlorinated biphenyls, radon, petroleum and any derivative thereof or
     any common law theory based on nuisance or strict liability.

          "Event of Default" has the meaning set forth in Section 14.1.

          "Existing Encumbrances" has the meaning set forth in Section 16.2.

          "Expiration Date" means (i) if the Commencement Date is the first day
     of a month, the end of the 123/rd/ full calendar month following the
     Commencement Date; or (ii) if the Commencement Date is not the first day of
     a month, the end of the 123/rd/ full calendar month following the calendar
     month in which the Commencement Date occurs.

          "Extension Option" has the meaning set forth in Section 2.3.

          "Extension Term" has the meaning set forth in Section 2.3.

          "Fitness Space" has the meaning set forth in Section 18.1.

          "40 Second Avenue" means the existing building known as and numbered
     40 Second Avenue, Waltham, Massachusetts and any alterations and
     replacements thereto.

                                       2
<PAGE>
 
          "Ground Lease" means that Ground Lease to be entered into between
     Landlord, as landlord, and Waltham 40 LLC, as tenant, pursuant to Section
     16.2, pursuant to which the ground lease premises will be the parcel of
     land which is the site for 40 Second Avenue, as more particularly described
     on Exhibit A-2 attached hereto.
        -----------                 

          "Hazardous Substances" has the meaning set forth in Section 16.4.

          "Holidays" means New Year's Day, Memorial Day, July 4/th/, Labor Day,
     Thanksgiving, and Christmas.

          "Improvements" means the Base Building, the Leasehold Improvements,
     the Parking Facility and any other structures, pavement, landscaping,
     lighting fixtures or other improvements now or later constructed or
     installed upon the Land.

          "Interest Rate" means the Prime Rate plus 4% per annum, but if such
     rate exceeds the maximum interest rate permitted by Law, such rate will be
     reduced to the highest rate allowed by Law under the circumstances.

          "Land" means the real property which is to consist of the site on
     which the Building is to be located, as described on Exhibit A-1 and the
                                                          -----------        
     ground lease parcel as described on Exhibit A-2.
                                         ----------- 

          "Landlord" means Waltham 60/10 LLC, a Minnesota limited liability
     company.

          "Landlord's Notice Address" means:

               Waltham 60/10 LLC
               c/o Eagle Ridge Partners
               165 South Union Boulevard
               Lakewood, CO 80228
               Attention: Douglas McCormick

               with a copy to:

               Waltham 60/10 LLC
               The Colonnade
               Suite 960
               5500 Wayzata Boulevard
               Golden Valley, MN 55410
               Attention: William K. Hoeg

                                       3
<PAGE>
 
               And to:

               The Beal Companies
               177 Milk Street
               Boston, Massachusetts 02109-3410
               Attention: Michael Manzo

          "Landlord's Rent Address" means:

               Waltham 60/10 LLC
               c/o Eagle Ridge Partners
               165 South Union Boulevard
               Lakewood, CO 80228
               Attention: Douglas McCormick

          "Landlord's Representative" means Peter B. Nichols or William S.
     Byrney, provided that any Change Order which increases the cost of the
     Landlord's Work by $25,000 or more shall also require the written approval
     of William Hoeg or John Scholz, or such other person as may from time to
     time be designated by William Hoeg or Landlord by notice to Tenant.

          "Landlord's Work" means the construction and installation of the Base
     Building and the Leasehold Improvements.

          "Laws" means any and all present or future federal, state or local
     laws, statutes, ordinances, rules, regulations or orders of any and all
     governmental or quasi-governmental authorities having jurisdiction.

          "Leasehold Improvements" has the meaning set forth in Paragraph 3 of
     the Work Letter.

          "Leasehold Improvements Allowance" has the meaning set forth in
     Paragraph 8(a) of the Work Letter.

          "Leasehold Improvements Design Documents" has the meaning set forth in
     Paragraph 4 of the Work Letter.

          "Leasehold Improvements Plans" has the meaning set forth in Paragraph
     5 of the Work Letter.

          "Lease Year" means each successive period of 12 calendar months during
     the Term ending on the same day and month (but not year, except in the case
     of the last Lease Year) as the day and month on which the Expiration Date
     will occur, provided the first Lease Year shall commence on the earlier of
     the Commencement Date or the Rent Commencement Date and shall end on the
     same day and month at least one full year later than the earlier of the
     Commencement Date or the Rent Commencement Date as the day and month on
     which the Expiration Date will occur.

                                       4
<PAGE>
 
          "Operating Costs" has the meaning set forth in Section 4.2.

          "Parking Facility" means the portion of the Building which is to
     contain approximately 890 parking spaces.

          "Permitted Activities" has the meaning set forth in Section 16.4.

          "Permitted Delays" means delays in the time by which Landlord shall be
     required to perform certain acts under this Lease to the extent that the
     performance of such act or acts shall be delayed by acts of God, fire,
     earthquake, windstorm, flood, explosion, collapse of structures, riot,
     civil commotion, war, strike, labor disputes, delays or restrictions by
     governmental bodies, Laws, inability to obtain or use necessary labor or
     materials, failure or disruption of utility services, Tenant's Delay or any
     other cause beyond the reasonable control of Landlord.

          "Preliminary Plans" means the plans and specifications for the Base
     Building that are identified in Exhibit B.
                                     --------- 

          "Premises" means the entirety of all square feet of Rentable Area
     within the Building except that portion of the Building that constitutes
     Parking Facility.

          "Prime Rate" means the prime or base rate of interest on corporate
     loans as published from time to time in the Midwest Edition of The Wall
                                                                    --------
     Street Journal, with any changes in such rate to be effective on the date
     --------------                                                           
     such change is published.

          "Projected Commencement Date" means June 30, 1999, as extended by
     Paragraph 4 of the Work Letter.

          "Punchlist" has the meaning set forth in the definition of
     "Substantially Completed".

          "Rent" means Base Rent and all Additional Rent.

          "Rent Commencement Date" means the date determined by (i) adding 91
     days to the Commencement Date, less (ii) the lesser of the following number
     of days (a) the actual number of days by which the Landlord's Work was
     Substantially Completed after the Projected Commencement Date, or (b) the
     aggregate number of days of Tenant's Delay.

          "Rentable Area" means an area in square feet that has been calculated
     in accordance with the methods of measuring rentable area of a single
     tenant building as described in the Standard Method for Measuring Floor
     Area in Buildings, ANSI 265.1 - 1996, as promulgated by the Building Owners
     and Managers Association (BOMA) International.

          "Required Completion Date" has the meaning set forth in Section
     3.2(d).

                                       5
<PAGE>
 
          "Substantially Completed" means, with respect to Landlord's Work, that
     (a) all of Landlord's Work contemplated by Article 3 of this Lease and the
     Work Letter has been substantially completed and a certificate of occupancy
     (temporary or final) has been issued by the appropriate governmental
     authority permitting use of the Premises for the use permitted under this
     Lease (upon Tenant's request, Landlord will deliver to Tenant a copy of
     such certificate of occupancy); (b) the Premises are broom clean and free
     from debris; (c) the HVAC system, Building elevators, lobbies, stairways
     and corridors are substantially completed and operating; (d) Landlord has
     delivered to Tenant a certificate of completion from Landlord's architect
     certifying substantial completion of the work described in the Base
     Building Plans and the Leasehold Improvements Plans; (e) Landlord has
     delivered to Tenant a punchlist (the "Punchlist") indicating any work
     remaining to be completed or corrected in the Premises which work remaining
     to be completed or corrected in the Premises is of such a nature that it
     will not materially and adversely interfere with Tenant's use and occupancy
     of the Premises and the completion of such work will not materially or
     adversely affect Tenant's use or occupancy of the Premises; and (g)
     Landlord has satisfied (a) through (f) of this definition prior to the
     expiration of the 30 day period specified in the notice given by Landlord
     to Tenant pursuant to Section 3.2(c)(ii) and the date for such completion
     specified in such notice given by Landlord to Tenant pursuant to Section
     3.2(c)(ii) has occurred.

          "Taxes" means, with respect to each tax fiscal year wholly or
     partially included in the Term, the following taxes which are due and
     payable in such tax fiscal year:  all personal property taxes of Landlord
     relating to Landlord's personal property located in the Premises and used
     or useful in connection with operating and maintaining the Premises; real
     estate taxes and installments of general or special assessments, including
     interest thereon, relating to the Land and Building including any such
     taxes or any such assessments that are levied with respect to the Parking
     Facility that are allocated to the Building as provided in Section 4.3; all
     fees of attorneys, appraisers and other consultants incurred in connection
     with any efforts to appeal, abate, or reduce any such Taxes; all other
     governmental charges, general and special, ordinary and extraordinary,
     foreseen and unforeseen, of any kind and nature whatsoever; and any other
     tax, however described, levied or assessed by the United States of America
     or the state in which the Premises are located or the City of Waltham,
     against Landlord or against all or any part of the Land and Building as a
     result of Landlord's ownership of the Land and Building or the rents
     therefrom.  Taxes will not include any income tax, estate tax or
     inheritance tax of Landlord.

          "Tenant's Cost" means the total cost of preparing the Leasehold
     Improvements Plans, obtaining all necessary permits for, and constructing
     and installing, the Leasehold Improvements in the Base Building, and
     providing any required services during construction of the Leasehold
     Improvements (such as refuse removal), excluding electricity (which will be
     provided at Landlord's cost).

          "Tenant's Cost Proposal" has the meaning set forth in Paragraph 6 of
     the Work Letter.

                                       6
<PAGE>
 
          "Tenant's Delay" means the aggregate days of: (a) each day of delay by
     Tenant in any performance which is described herein or in the Work Letter
     as a Tenant's Delay, (b) each day of delay by reason of any Change Orders
     or changes in any drawings, plans or specifications requested by Tenant
     which is described in Section 3.8 as a Tenant's Delay; (c) each day of
     delay in Landlord's Work by reason of any failure by Tenant to review or
     approve promptly any item requiring Tenant's review or approval, which is
     not described herein or in the Work Letter as a Tenant's Delay; or (d) each
     day of delay in Landlord's Work by reason of any other act or omission of
     Tenant or Tenant's architects, engineers, contractors or subcontractors.

          "Tenant's Excess Cost" has the meaning set forth in Paragraph 8(b) of
     the Work Letter.

          "Tenant's Notice Address" means,

               Before the Premises is Substantially Completed:

               Renaissance Worldwide, Inc.
               189 Wells Avenue
               Newton, MA 02159
               Attention: General Counsel
 
               After the Premises is Substantially Completed:

               Tenant's address at the Premises

               In either event, with a copy to:

               Renaissance Worldwide, Inc.
               189 Wells Avenue
               Newton, MA 02159
               Attention: General Counsel

          "Tenant's Representative" means Duncan Andrews or such other person
     as may from time to time be designated by Mr. Andrews or by Tenant by
     notice to Landlord.
     
          "Term" means the duration of this Lease, which will be approximately
     10 years and three (3) months beginning on the earlier of the Commencement
     Date or the Rent Commencement Date and ending on the Expiration Date,
     unless terminated earlier or extended further as provided in this Lease.

          "Work Letter" means Exhibit C to this Lease.
                              ---------               

          "Work Schedule" has the meaning set forth in Paragraph 2 of the Work
     Letter.

                                       7
<PAGE>
 
      Section 1.2   Exhibits.  The Exhibits listed below are attached to and
incorporated in this Lease.  In the event of any inconsistency between such
Exhibits and the terms and provisions of this Lease, the terms and provisions of
the Exhibits will control.  The Exhibits to this Lease are:
 
          Exhibit A   -   Legal Description of the Land
          Exhibit B   -   Preliminary Plans and Specifications
                          for the Base Building
          Exhibit C   -   Work Letter
          Exhibit D   -   Janitorial Standards
          Exhibit E   -   Existing Encumbrances
          Exhibit F   -   MGP Lease Requirements
 
                                   ARTICLE 2
                                DEMISE AND TERM

      Section 2.1   Premises.  Landlord hereby demises and leases the Premises
to Tenant, and Tenant hereby rents and takes the Premises from Landlord, subject
to and with the benefit of the terms, covenants, conditions and provisions of
this Lease, of the Existing Encumbrances and Future Encumbrances, as defined in
Section 16.2 hereof.   The rights of Tenant hereunder shall include non-
exclusive rights of access over and use of the Common Area.
 
      Section 2.2   Term.  The Term of this Lease shall begin upon the earlier
of the Commencement Date or the Rent Commencement Date and shall continue until
the Expiration Date, unless sooner terminated or extended further as herein set
forth.

      Section 2.3   Extension Option.  Tenant shall have the option (the
"Extension Option") to extend the Term of this Lease for one (1) period of five
(5) years (the "Extension Term") with respect to all, but not less than all, of
the Premises, in accordance with the following provisions:

      (a) Such option shall be exercisable by written notice (an "Extension
          Notice") delivered to Landlord not earlier than twenty (20) months
          nor later than eighteen (18) months prior to the Expiration Date. If
          Tenant fails to deliver the Extension Notice in accordance with such
          time restriction, the Extension Option contemplated by this Section
          2.3 shall be deemed waived and of no further force and effect, time
          being of the essence. The rate of Base Rent payable by Tenant during
          the Extension Term upon the entirety of the Premises shall be an
          amount equal to ninety-five percent (95%) of the "Extension Market
          Rate" determined as of the date which is 18 months prior to the end
          of the Term.

     (b)  For purposes hereof the phrase "Extension Market Rate" means the base
          rent at the per annum rate at which the entirety of the Premises, in
          its then "as-is" condition except for recarpeting and repainting to be
          provided by Landlord,  would be leased to a single tenant on a basis
          which is net to the same extent as this Lease, by a willing landlord
          not compelled to lease and to a willing third-party tenant not
          compelled to 

                                       8
<PAGE>
 
          lease (based on the obligations and rights of Landlord and Tenant
          under this Lease to the extent applicable during the Extension Period,
          the length of the Extension Term, and taking into account the
          amenities of the Building, that no commissions are payable by Landlord
          in connection with such extension). If Tenant properly and timely
          delivers the Extension Notice and does not deliver an Extension
          Retraction Notice, Landlord shall recarpet and repaint the Premises on
          or before the commencement of the Extension Term consistent with the
          standards of the initial Leasehold Improvements.

     (c)  Landlord shall, within thirty (30) days after receipt of the Extension
          Notice, give Tenant written notice ("Landlord's Extension Rate
          Notice") of Landlord's determination of the Extension Market Rate. If
          Tenant does not agree with Landlord's determination of the Extension
          Market Rate, Tenant shall give Landlord written notice of that
          disagreement within fifteen (15) days of receipt of Landlord's
          Extension Rate Notice, stating the amount which Tenant believes the
          Extension Market Rate should be, and Landlord and Tenant shall
          endeavor in good faith to agree on the Extension Market Rate. If
          Tenant fails to give Landlord timely notice of such disagreement,
          Tenant shall be deemed to have accepted Landlord's determination of
          the Extension Market Rate. If Landlord and Tenant have not agreed as
          to the Extension Market Rate within thirty (30) days after Tenant's
          receipt of Landlord's Extension Rate Notice, either party may deliver
          to the other party a written demand (the "Valuation Demand") that the
          Extension Market Rate be determined by an expert, which demand shall
          include the names of at least three (3) reputable real estate experts
          who are members of the American Society of Real Estate Counselors or
          of a successor body hereafter constituted and exercising similar
          functions (referred to hereinafter as "ASREC" and who have no
          affiliation with either party and who have not less than 10 years of
          experience in appraising, managing or brokering office properties
          similar to the Premises in the greater Boston Metropolitan Area. The
          expert shall be chosen through the mutual agreement of Landlord and
          Tenant, which agreement shall be reached within twenty (20) days after
          the delivery of the Valuation Demand. Provided an agreement upon
          selection of the expert is so reached, the expert shall be directed to
          complete the determination of the Extension Market Rate within thirty
          (30) days of such expert's appointment. The expert's determination of
          the Extension Market Rate shall be binding upon the parties. In the
          event the parties are unable to agree upon the identity of an expert
          within twenty (20) days of the delivery of the Valuation Demand, each
          party shall, within twenty-five (25) days of the delivery of the
          Valuation Demand, appoint its own expert, subject to the above
          qualifications. Such appointment shall be confirmed in a writing
          identifying the expert delivered to the other party within said 
          twenty-five (25) day period. If either of the parties fails to appoint
          an expert within said twenty-five (25) day period, then the one expert
          appointed shall be the sole expert and the provisions of this
          subsection (c) relating to more than one expert shall not apply. If
          each party appoints an expert, a third expert shall be jointly
          appointed by the first two experts. If the first two experts are
          unable to agree on a third expert within ten (10) days after the
          appointment of the second expert, then the highest ranking available
          officer of the

                                       9
<PAGE>
 
          Massachusetts chapter of the ASREC who is not affiliated with either
          party shall appoint the third expert. If none of the three
          determinations deviates from the mean of all three determinations by
          more than 10%, the mean of all three determinations shall be the
          Extension Market Rate. If one of the three determinations deviates
          from the mean of all three determinations by more than 10%, such
          determination shall be discarded and the Extension Market Rate shall
          be the mean of the other two. If two or all three of the
          determinations deviate from the mean of all three determinations by
          more than 10%, the Extension Market Rate shall be the median of the
          three determinations. The Extension Market Rate as determined in
          accordance with the provisions of this Section 2.3 shall be binding
          upon the parties. Except as set forth in Section 2.3(d), all necessary
          and reasonable costs and expenses of any valuations performed pursuant
          to this Section 2.3 shall be shared equally by Landlord and Tenant,
          and all agreements with experts appointed in accordance with this
          Section 2.3 shall provide that such experts shall complete their
          determinations within thirty (30) days of such appointment and provide
          prompt notice to Landlord and Tenant. To the extent that the Extension
          Option is effectively exercised, Landlord and Tenant shall execute and
          deliver an amendment to this Lease that is reasonable in form and that
          memorializes the occurrence and effect of such extension and such rate
          of Base Rent, which amendment shall be executed and delivered within
          ten (10) days following the determination of the Extension Market
          Rate.

     (d)  Notwithstanding the foregoing, upon the determination of the Extension
          Market Rent in accordance with the foregoing provisions of this
          Section 2.3 for the Extension Option, Tenant shall have the right to
          retract its exercise of this option through the delivery of written
          notice to that effect to Landlord (the "Extension Retraction Notice");
          provided, if the Extension Retraction Notice is not delivered to
          Landlord within thirty (30) days after the date of the determination
          of the Extension Market Rent and notice thereof to Landlord and
          Tenant, the right to retract the exercise of the option to extend the
          Lease for the Extension Term shall be deemed waived and of no further
          force and effect and the Lease shall be deemed extended for the
          Extension Term in accordance with the foregoing provisions of this
          Section 2.3.  In the event of the timely delivery by Tenant to
          Landlord of an Extension Retraction Notice, the Lease shall expire as
          of the Expiration Date and Tenant shall, within thirty (30) days of
          the date of Landlord's delivery of an invoice therefor and as
          Additional Rent hereunder, reimburse Landlord for all costs reasonably
          incurred by Landlord in performing Landlord's obligations under this
          Section 2.3 and as a direct consequence of Tenant's delivery of the
          Exercise Notice including, without limitation, all fees incurred by
          Landlord in connection with the valuation required by Section 2.3(c)

     (e)  Tenant shall have no further options to extend the term of this Lease
          beyond the expiration date of the Extension Term.  Except for its
          obligation to repaint and recarpet the Premises as provided in Section
          2.3(b), Landlord shall not be obligated to perform any leasehold
          improvement work in the Premises or give Tenant an allowance for any
          such work or for any other purposes for the Extension Term. Except for
          the rate of Base Rent and except as otherwise provided herein, all of
          the terms and provisions of this Lease shall remain the same and in
          full force and effect during the Extension Term.

                                       10
<PAGE>
 
     (f)  Notwithstanding the foregoing, the Extension Option contemplated by
          this Section 2.3 shall, whether or not an Extension Notice has
          theretofore been delivered, automatically terminate and become null
          and void and of no further force and effect upon the earlier to occur
          of (i) the termination of this Lease, or (ii) the failure of Tenant to
          timely or properly exercise the Extension Option.

     (g)  Notwithstanding the foregoing, in the event that, upon delivery of the
          Extension Notice or upon the commencement of the Extension Term,
          Tenant has sublet or assigned 50% or more of the Rentable Area of the
          Premises (not including in such calculation of the Rentable Area
          sublet or assigned the Rentable Area sublet or assigned to a
          transferee permitted by Section 9.1(d)), such Extension Notice shall
          be null and void.

     Section 2.4  Right of First Offer to Purchase.

     (a)  In the event that, during the Term, Landlord desires to sell the Land,
the Building and, at Landlord's option, Landlord's ground lessor's interest in
40 Second Avenue (such parcel which Landlord desires to sell being the "Offer
Parcel"), to a party who is not a Landlord Party, Landlord shall first offer to
sell the Offer Parcel to Tenant by delivering a written notice to Tenant (the
"Offer Notice") setting forth in good faith all material business terms of an
offer that Landlord would be willing to accept, including the gross purchase
price which, subject to adjustments and prorations, will be payable in cash to
Landlord.  Tenant shall have twenty (20) days after the delivery of the Offer
Notice, time being of the essence, in which to deliver to Landlord written
notice of its acceptance of all of the terms designated in the Offer Notice (the
"Notice of Acceptance"); provided, it shall be a condition precedent to the
effectiveness of any Notice of Acceptance that it be accompanied by a deposit of
earnest money in the amount set forth in the Offer Notice, but such earnest
money shall not be in excess of five percent (5%) of the gross purchase price.
Such earnest money shall be payable to and held in escrow by Landlord's counsel
pursuant to the terms hereof.

     (b) If Tenant delivers the Notice of Acceptance in a timely manner, then
the closing of the sale of the Offer Parcel by Landlord to Tenant will occur on
the 30/th/ day after the delivery to Landlord of the Notice of Acceptance, or by
mutual agreement on an earlier date.  Such closing will occur at the offices of
Landlord's attorneys in Boston, Massachusetts.  At such closing, (i) Landlord
will convey the Offer Parcel to Tenant or Tenant's designee by quit claim deed,
free and clear of all monetary liens and encumbrances but subject to the
Permitted Exceptions; (ii) Tenant will pay the purchase price to Landlord by
wire transfer or in other immediately available funds, subject to a credit for
Tenant's earnest money deposit and the adjustments and prorations described
below; (iii) No proration of Taxes or Operating Expenses will occur since Tenant
is responsible hereunder to pay Taxes and Operating Expenses as part of the
Rent; (iv) Landlord will deliver a copy of the most current as-built survey in
its possession; Tenant will pay for a Title Commitment for an ALTA extended
coverage (i.e., with all standard printed exceptions deleted) title insurance
          -----                                                              
policy for Tenant in the amount of the purchase price, subject to the Permitted
Exceptions and for all title insurance 

                                       11
<PAGE>
 
premiums payable in connection with the issuance of a title policy and any
endorsements thereto desired by Tenant; (v) each party will pay its own closing
costs in accordance with prevailing custom and practice in the Boston
Massachusetts Metropolitan Area; (vi) Landlord shall pay any transfer tax due in
connection with the transaction; and (vii) all other terms and conditions not
specified in the Offer Notice herein shall be as handled in accordance with
prevailing customs and procedures in the Boston Massachusetts Metropolitan Area.
Promptly after Tenant delivers the Notice of Acceptance, Tenant will obtain and
deliver to Landlord a Title Commitment committing to insure title to the Offer
Parcel in Tenant in the amount of the purchase price. Tenant will have a period
of 10 days after delivery of the Title Commitment in which to review the state
of Landlord's title to the Premises, to negotiate with the title company
concerning the deletion of any exceptions shown on the Title Commitment or to
terminate its Notice of Acceptance. It will be Landlord's responsibility to
obtain deletion of all exceptions other than Permitted Exceptions on or before
closing, deletion of which is customary. As used herein, the "Permitted
Exceptions" will mean taxes, all easements and other matters described on
Exhibit E attached hereto, any matters shown by the as-built survey of the
---------
Offer Parcel which Landlord will deliver to Tenant, as provided above, liens or
encumbrances which Tenant would be required to pay pursuant to this Lease, such
as Taxes for periods subsequent to the Commencement Date and such additional
matters which are Future Encumbrances as defined in Section 16.2 hereof.
"Permitted Exceptions" will not include any standard printed exceptions which
are customarily deleted or any monetary liens or encumbrances (other than any
such liens or encumbrances which Tenant would be required to pay pursuant to
this Lease, such as Taxes for periods subsequent to the Commencement Date).
Landlord agrees that it may not encumber the Land or the Building in any manner
not permitted by Section 16.2 hereof, other than mortgages and other such
voluntary encumbrances and such other liens and encumbrances which will be
discharged or satisfied of record at Closing of the purchase of the Offer Parcel
by Tenant. If any dispute arises over the prevailing customs and practices in
Boston, Massachusetts Metropolitan Area which are applicable to such purchase
and sale and are not provided herein or in the Offer Notice, and the Landlord
and Tenant are unable to agree on such issues by the closing date, such issues
shall be submitted to Arbitration, but such Arbitration shall not delay closing
and appropriate escrows will be established so that the positions of both
parties are protected pending the outcome of such Arbitration.

      (c) If Tenant does not deliver the Notice of Acceptance or terminates such
exercise as provided above, Tenant will, upon Landlord's request, execute a
certificate or amendment to this Lease confirming that Tenant has no further
rights under this Section 2.4 (except as provided in Section 2.4(d)).  If Tenant
delivers the Notice of Acceptance, does not terminate such exercise within such
10-day period as provided above and then fails to close its purchase of the
Offer Parcel in accordance with the foregoing provisions, Landlord may either
(i) terminate Tenant's right to purchase the Offer Parcel pursuant to this
Section 2.3 and shall be entitled to retain the earnest money deposit as
liquidated damages, it being understood and agreed that Landlord's damages in
such event would be difficult to ascertain and that the earnest money deposit is
a reasonable estimate of such damages, or (ii) may sue Tenant for specific
performance.   If Tenant delivers the Notice of Acceptance, does not terminate
such exercise within such 10-day period and then Landlord fails to close its
sale of the Offer Parcel in accordance with the foregoing provision, Tenant may
sue Landlord for specific performance or damages.

                                       12
<PAGE>
 
     (d)  If Tenant fails to deliver the Notice of Acceptance in a timely
manner, the right of first offer contemplated by this Section shall be deemed
terminated and of no further force and effect and Landlord may thereafter sell
the Offer Parcel to any other party; provided, Landlord shall not thereafter
enter into an agreement to sell the Offer Parcel to any other third party which
is not a Landlord Party for a gross purchase price (which may be payable in
whole or in part in cash or in interests in the purchaser) that is less than
ninety-five percent (95%) of the gross purchase price identified in the Offer
Notice without first delivering a new Offer Notice to Tenant containing such
revised term. In the event Landlord does not enter into a purchase agreement to
sell the Offer Parcel within 12 months after the expiration of the twenty (20)
day period by which Tenant could have given a Notice of Acceptance, then
Tenant's right of first offer shall be revived and Landlord shall again give
Tenant a right of first offer, as provided in this Section 2.4, in connection
with any subsequent sale of the Offer Parcel.

     (e)  Notwithstanding the foregoing,

          (i)   the right of first offer contemplated by this Section, shall not
                be applicable with respect to:

                (A) any sale of the Premises for which a binding purchase
                    agreement is executed by Landlord prior to the Commencement
                    Date;

                (B) any transfer in the nature of the grant of a mortgage or
                    other encumbrance to secure indebtedness of Landlord;

                (C) any transfer of the Premises to a Landlord Party; or

                (D) any transfer of the Premises to the purchaser at a
                    foreclosure sale or to the grantee named in a deed in lieu
                    of foreclosure;

                provided, however, that this right of first offer will survive
                any such transfer or transfers pursuant to (A), (B), (C) and (D)
                above, and shall be binding upon the transferee, including any
                such Landlord Party, such purchaser at a foreclosure sale or
                such grantee of a deed in lieu of foreclosure;

          (ii)  the right of first offer contemplated by this Section shall be
                deemed terminated upon the earliest to occur of the following:

               (A)  the termination of Tenant's right to possession of the
                    Premises;

               (B)  the assignment or subletting of an aggregate of more than
                    50% of the total number of square feet of Rentable Area of
                    the Premises, not including in such calculation of the
                    Rentable Area sublet or assigned the Rentable Area of the
                    Premises sublet or assigned to a transferee permitted by
                    Section 9.1(d), or

                                       13
<PAGE>
 
                (C)  the expiration or earlier termination of the Lease; and

          (iii) This right of first offer and any right to purchase the Premises
                resulting therefrom is personal to Tenant and may not be
                assigned to and shall not benefit any person or entity
                including, without limitation, any sublessee or assignee of any
                part of the Premise, other than a transferee permitted by
                Section 9.1(d).

      (f) For the purposes of this Section 2.4, a person or entity is a
"Landlord Party" if (i) Landlord or one or more of the beneficial owners of
Landlord owns at least a 25% interest in such person or entity, whether directly
or indirectly, (ii) such person or entity holds a beneficial interest in
Landlord, or (iii) any person or entity at least 25% of the beneficial interest
of which are held by a person or entity which holds a beneficial interest in
Landlord.

      (g) Prior to transferring the Premises to a Landlord Party, Landlord shall
deliver prior written notice to Tenant of such proposed transfer, together with
evidence of the proposed transferee's status as a Landlord Party and the
transferee's acknowledgment that it will be bound by this right of first offer.
If Tenant fails to object to any such proposed transferee as being a Landlord
Party within 10 days after receipt of said notice and evidence, Tenant shall
have no further right to object to such transfer.

                                   ARTICLE 3
               CONSTRUCTION; DELIVERY AND ACCEPTANCE OF PREMISES

 
      Section 3.1   Landlord's Construction Obligations.  Subject to and in
accordance with the provisions of this Article 3 and the Work Letter, Landlord
will (i) at Landlord's sole cost and expense, design, construct and install the
Base Building on the Land; and (ii) at Landlord's cost up to the amount of the
Leasehold Improvements Allowance and otherwise at Tenant's sole cost and
expense, design, construct and install the Leasehold Improvements.

      Section 3.2   Delivery.

      (a) Early Possession.  Prior to Landlord's Work being Substantially
          ----------------                                               
          Completed Landlord shall allow Tenant to enter the Premises to
          commence fixturing, provided (i) such fixturing will not, in
          Landlord's reasonable determination, interfere with or interrupt the
          efficient and timely performance of the remaining Landlord's Work; and
          (ii) Tenant shall have given Landlord evidence of Tenant's insurance
          as required by Section 7.2.

      (b) Tender of Possession Upon Substantial Completion.  At such time as the
          ------------------------------------------------                      
          Landlord's Work is Substantially Completed, Landlord shall tender
          possession to Tenant of the Premises, even if there may then be
          portions of the Landlord's Work that are not completed so long as such
          incomplete work or the completion thereof does not affect

                                       14
<PAGE>
 
          Tenant's ability to commence or complete fixturing the Premises or
          materially and adversely interfere with Tenant's use and occupancy of
          the Premises.

      (c) Notice of Anticipated Substantial Completion.  For the convenience of
          --------------------------------------------                         
          Tenant, Landlord shall,

          (i)    make reasonable efforts to deliver 90 days' advance notice to
                 Tenant of the date on which Landlord anticipates that the
                 Landlord's Work will be Substantially Completed; provided,
                 however, that:

                 (1)   Landlord's failure to deliver such notice shall not
                       constitute a default under this Lease and Landlord shall
                       in no way be liable for failing to give such 90-day
                       notice;

                 (2)   the delivery of such 90-day notice shall not be a
                       condition to Landlord's having Substantially Completed
                       the Landlord's Work; and

                 (3)   Landlord shall not be bound by its estimate of the date
                       on which the Landlord's Work will be Substantially
                       Completed; and

          (ii)   deliver 30 days' advance notice to Tenant of the date on which
                 Landlord anticipates that Landlord's Work will be Substantially
                 Completed; provided however, that:

                 (1)   Landlord may retract any such notice given to Tenant and
                       give a revised notice of such date, which revised notice
                       shall start a new 30 day period prior to the anticipated
                       date on which Landlord's Work will be Substantially
                       Completed; and

                 (2)   Landlord's failure to deliver such notice shall not
                       constitute a default under this Lease and Landlord shall
                       not be liable for failing to give such 30-day notice;
                       however, Landlord's Work will not be Substantially
                       Completed unless the conditions in subsection (a) through
                       (f) of the definition of Substantially Completed are
                       satisfied prior to the expiration of such 30-day period
                       and the date for such completion specified in such 30-day
                       notice has occurred.

     (d)  Effect of Delays.  Landlord shall use reasonable efforts to deliver
          ----------------                                                   
          possession of the entirety of the Premises with the Landlord's Work
          Substantially Completed on or before the Projected Commencement Date,
          subject to Permitted Delays. It is acknowledged that time is of the
          essence of the completion of the Landlord's Work and that Tenant will
          suffer financial loss if the Landlord's Work is not Substantially
          Completed by August 31, 1999 (the "Required Completion Date"). The
          parties also recognize that delay, expense and difficulty would be
          involved in proving in a

                                       15
<PAGE>
 
          legal or arbitration proceeding the actual loss suffered by Tenant if
          Landlord's Work is not Substantially Completed by the Required
          Completion Date. Accordingly, in the event Landlord's Work is not
          Substantially Completed on or before the Required Completion Date,
          subject to Permitted Delays, Landlord and Tenant agree that the
          following is a reasonable approximation of the damages that Tenant
          would incur and Tenant shall be entitled, as liquidated damages for
          such delay and not as a penalty, to the following:

          (i)   In the event that the Landlord's Work is Substantially Completed
                in the period between the Required Completion Date, as extended
                by Permitted Delays, and February 29, 2000, which date shall be
                extended only by Tenant's Delay, Tenant shall be entitled to a
                credit (the "Delay Credit") in an amount equal to the greater of
                (i) the amount which Landlord actually collects from its
                contractor for failing to have Substantially Completed the
                Landlord's Work on or before the Required Completion Date, as
                extended by Permitted Delays, after recovery of Landlord's costs
                and expenses incurred in connection with such collection, or
                (ii) $1,500 multiplied by the number of days that elapse between
                the day following the Required Completion Date, as extended by
                Permitted Delays, and the date the Landlord's Work is
                Substantially Completed. Landlord shall make reasonable efforts
                to include in the construction contract for Landlord's Work a
                payment to Landlord equal to the product of $4,000, multiplied
                by the number of days that elapse between the day following the
                Required Completion Date, as extended by Permitted Delays, and
                the date the Landlord's Work is Substantially Completed, or as
                close thereto as is reasonably possible. In the event the
                Landlord's Work is not Substantially Completed on or before the
                Required Completion Date, as extended by Permitted Delays,
                Landlord shall use its reasonable efforts to enforce such
                penalty provision in the construction contract for the benefit
                of Tenant. Any Delay Credit shall be applied as a credit against
                the sum of Rent due in each month during the Term until the
                Delay Credit is fully credited; or

          (ii)  In the event that the Landlord's Work has not been Substantially
                Completed by January 31, 2000 (the "Incompletion Termination
                Date"), Tenant shall have the option to terminate this Lease by
                the delivery of written notice to that effect (the "Incompletion
                Termination Notice") to Landlord within thirty (30) days after
                the Incompletion Termination Date. In the event of the timely
                delivery of an Incompletion Termination Notice, this Lease shall
                be deemed terminated and of no further force and effect if
                Landlord's Work is not Substantially Completed within a period
                equal to the sum of (a) thirty (30) days after receipt of such
                notice by Landlord and (b) the aggregate number of days of
                Tenant's Delay. In the event of such termination, the parties
                shall cooperate in the execution of a written instrument that is
                reasonable in form and that memorializes such termination and
                Landlord shall, within thirty (30) days after such termination,
                pay to Tenant the

                                       16
<PAGE>
 
                aggregate principal amount of the Delay Credit that has accrued
                to the date of termination and Landlord and Tenant shall be
                discharged from all further obligations hereunder.

     Section 3.3    Operating Costs After Tender of Possession but Prior to Rent
Commencement Date.  Notwithstanding anything in Section 4.2 to the contrary, but
subject to Section 4.1, for the period starting on the date Landlord first
tenders possession of all of the Premises to Tenant pursuant to Section 3.2 and
ending on the Rent Commencement Date, Tenant shall pay the Operating Costs,
regardless of whether Tenant is in possession or occupancy of the entire
Premises during all or any portion of such period, but such amount shall be
reduced in accordance with the following schedule:

             Period
       (days prior to Rent          Percentage of Operating
        Commencement Date)          Costs Payable by Tenant
        ------------------          -----------------------

          90-61 days                                0%
          60-31 days                               33 1/3%
          30-0 days                                66 2/3%
 
      Section 3.4   Punch Lists.  Tenant's taking possession of the Premises
will be conclusive evidence that such Premises was in good order and
satisfactorily condition, and that all of Landlord's Work in or to the Premises
was satisfactorily completed when Tenant took possession, except as to any
latent defects or uncompleted items identified on (i) a punch list prepared and
signed by Landlord's Representative and Tenant's Representative after an
inspection of the Premises by both such parties made within five business days
after Landlord tenders possession of the Premises to Tenant, or (ii) a punch
list which Landlord will cause its architect to prepare on or before the same
date, and except as to any latent defects in Landlord's Work of which Tenant
notifies Landlord within one year after the Commencement Date.  Landlord will
commence the completion or correction of any matters set forth on such punch
lists within 10 days after such lists are received by Landlord, will complete
all items within 30 days after such lists are prepared, except for any of such
items which, due to reasons beyond Landlord's control, cannot be completed
within such time and, as to such delayed items, Landlord will thereafter
diligently pursue completion.  Landlord will not be responsible for any items of
damage caused by Tenant, its agents, independent contractors or suppliers.  No
promises to construct, alter, remodel or improve the Premises, and no
representations concerning the condition of the Premises, have been made by
Landlord to Tenant other than as may be expressly stated in this Lease.  Any
dispute between Landlord and Tenant as to which items should be included on such
punch lists, or which items on such punch lists have been completed, shall be
subject to Arbitration.

      Section 3.5   Representatives.  Landlord appoints Landlord's
Representative to act for Landlord in all matters covered by this Article 3 and
the Work Letter.  Tenant appoints Tenant's Representative to act for Tenant in
all matters covered by this Article 3 and the Work Letter.  All inquiries,
requests, instructions, authorizations and other communications with respect to
the matters covered by this Article 3 and the Work Letter will be made by and to
Landlord's Representative or

                                       17
<PAGE>
 
Tenant's Representative, as the case may be. Only Tenant's Representative and
Landlord's Representative may authorize Change Orders. Tenant will not interfere
with Landlord's architect, engineers and contractors or any of their agents or
employees in the performance of their respective obligations with regard to
matters covered by this Article 3 or the Work Letter.

      Section 3.6   Base Building Plans.  Tenant has approved the Preliminary
Plans, including the Floor Plate and Background Drawings, the Civil/Site Design
Documents and the Detailed Base Building Design Documents, delivered to Tenant
and shown on Schedule 1 to the Work Letter.  Landlord has delivered the Base
Building Plans to Tenant based on the Preliminary Plans.  Within 10 days after
receipt of the proposed Base Building Plans, Tenant will either approve the same
in writing or notify Landlord in writing of how the proposed Base Building Plans
are inconsistent with the Preliminary Plans and how the Base Building Plans must
be changed in order to make them consistent with the Preliminary Plans.  Tenant
may not object to any portion of the Base Building Plans which is consistent
with the Preliminary Plans.  Each day following the tenth day after the proposed
Base Building Plans are submitted to Tenant until Tenant approves the Base
Building Plans or delivers such notice of objections, will be a day of Tenant's
Delay.  Upon receipt of Tenant's notice of objections, Landlord will cause its
architect to prepare revised Base Building Plans according to such notice and
submit the revised Base Building Plans to Tenant.  Upon submittal to Tenant of
the revised Base Building Plans, and upon submittal of any further revisions,
the procedures described above will be repeated.   Tenant shall approve or make
objections to the other design and construction documents to be delivered to
Tenant in accordance with Schedule 1 to the Work Letter within 5 business days
after receipt thereof and otherwise in accordance with the procedures described
above.

      Section 3.7   Base Building Construction.  At such time as Base Building
Plans have been prepared and have been approved in writing by both Landlord,
Tenant and Landlord's mortgagee, and Landlord has obtained all necessary
building permits, Landlord will cause the Base Building to be constructed or
installed on the Land in a good and workmanlike manner and according to the
approved Base Building Plans and all applicable Laws.

      Section 3.8   Change Orders.  Tenant's Representative may request changes
in the work consistent with the Preliminary Plans and the Base Building Plans
only by written request to Landlord's Representative on a form approved by
Landlord.  Tenant's Representative may request, in the manner contemplated by
Paragraph 8(c) of the Work Letter with respect to the Leasehold Improvements,
other changes in the Leasehold Improvements.  All changes requested by Tenant
will be subject to Landlord's prior written approval (which approval, in the
case of changes to the Leasehold Improvements Plans, will not be unreasonably
withheld).  Prior to commencing any change in the Base Building Plans or the
Leasehold Improvements Plans, whether requested by Tenant or not, Landlord will
prepare and deliver to Tenant, for Tenant's approval, a change order ("Change
Order") identifying the total cost of such change, which will include associated
architectural, engineering and construction contractor's fees, and the total
time that will be added to the construction schedule by such change and to the
Projected Commencement Date, the Required Completion Date and the Incompletion
Termination Date; provided that Landlord shall not be required to obtain
Tenant's approval of any Change Order initiated by Landlord which is both
consistent with the Preliminary Plans and which does not materially alter the
Base Building Plans 

                                       18
<PAGE>
 
or cause a change in or delay in the completion of the Leasehold Improvements.
If Tenant fails to approve or object to any Landlord-initiated Change Order for
which Tenant's approval is required within five business days after delivery by
Landlord of such Change Order, Tenant shall be deemed to have approved such
Change Order and Landlord may proceed to perform the change. If Tenant fails to
approve any such Tenant-initiated Change Order within five business days after
delivery by Landlord of such Change Order, Tenant will be deemed to have
withdrawn the requested change and Landlord will not proceed to perform the
change. Upon Landlord's receipt of Tenant's approval, Landlord will proceed to
perform the change. Any net additional costs resulting from a Tenant-initiated
Change Order will become a part of Tenant's Cost and, if there exists Tenant's
Excess Cost, such Tenant's Excess Cost will be paid to Landlord in accordance
with the provisions of Paragraph 8(b) of the Work Letter. Any delay in the
Landlord's Work being Substantially Completed by the Projected Commencement
Date, the Required Completion Date or the Incompletion Termination Date caused
by a Tenant-requested Change Order shall be Tenant's Delay.

      Section 3.9   No Interference with Landlord's Work.  Tenant acknowledges
that any work by Tenant in the Premises prior to the Landlord's Work being
Substantially Completed and the completion by Landlord of all punch list work
may impact on the performance of Landlord's Work.  Tenant further acknowledges
that all or a substantial portion of Landlord's Work will be performed by union
contractors.  In order to prevent delays and interference with the performance
of Landlord's Work, Tenant agrees to use union contractors for any construction
or fixturing work to be performed by it in the Premises and to cooperate with
Landlord in the scheduling and the conduct of Tenant's work in order to provide
for a harmonious work force, to prevent labor disputes, and so as not to
unreasonably interfere, restrict or delay the performance of Landlord's Work.

      Section 3.10  Adjustments Upon Completion.  As soon as practicable after
the completion of the Base Building, Landlord will cause its architect to
measure and certify to Landlord and Tenant the Rentable Area of the Premises.
If Tenant disputes such measurement within 30 days after Tenant is notified of
the same, then Tenant's architect and Landlord's architect will endeavor to
agree upon the Rentable Area of the Building and, if they are unable to do so
within 10 days, the dispute will be submitted to an independent third-party
architect mutually acceptable to both parties whose decision concerning the
Rentable Area of the Building (which will be made in accordance with the
definition thereof in this Lease),will be binding upon both parties.  If Tenant
does not so dispute the measurement by Landlord's architect, Tenant will be
deemed to have accepted such   measurement. At such time as such measurement has
been made by Landlord's architect and accepted (or deemed accepted) by Tenant,
upon the request of either party, Landlord and Tenant will execute a certificate
confirming such Rentable Area and the actual amounts (based on such Rentable
Area) of the Base Rent payable per month during the first through the fifth
Lease Years, the sixth through the tenth Lease Years, and the actual amount of
the Leasehold Improvements Allowance.  Prior to the execution of such
certificate, the Premises shall be presumed to contain 200,000 square feet of
Rentable Area, and Tenant will pay any additional Base Rent or Tenant's Excess
Cost owing, or Landlord will refund any Base Rent or Tenant's Excess Cost
previously overpaid by Tenant, upon the execution of such certificate.

                                       19
<PAGE>
 
                                   ARTICLE 4
                                     RENT

      Section 4.1   Base Rent.  Commencing on the Rent Commencement Date and
then continuing throughout the Term, Tenant agrees to pay Landlord Base Rent
according to this Section 4.1, without demand, deduction, setoff, abatement or
credit except as expressly contained in the Lease.  Base Rent during each Lease
Year of the Term will be payable in monthly installments in an amount equal to
1/12 of the amount obtained by multiplying the rate of Base Rent for such Lease
Year set forth in the definition of Base Rent in Section 1.1 by the number of
square feet of Rentable Area of the Premises, in advance, on or before the first
day of each and every month during the Term; if the number of days in the first
Lease Year is greater than 365 or 366 days, as applicable, such monthly rental
shall also be payable for each additional 30-day period, prorated for any
partial month as provided in the following sentence.  If the Rent Commencement
Date is a date other than the first day of a calendar month or if the Term ends
on a date other than the last day of a calendar month, Landlord will prorate
monthly Base Rent for the first month of the Term or the last month of the Term,
as the case may be, based upon the ratio that the number of days of the Term
within such month bears to the total number of days in such month.  Tenant
acknowledges that if there are more than 90 days of Tenant's Delay the Rent
Commencement Date may occur prior to the Commencement Date, and Tenant will be
obligated to pay Rent from and after such Rent Commencement Date notwithstanding
the fact that the Premises will not yet have been delivered to Tenant on such
Rent Commencement Date.

           Section 4.2  Operating Costs.  Except as provided in Section 3.3,
     Tenant shall pay the Operating Costs to Landlord, as Additional Rent,
     beginning on the Commencement Date and throughout the remainder of the
     Term.  As used in this Lease, the term "Operating Costs" shall mean any and
     all expenses, costs and disbursements of any kind and nature whatsoever
     paid or incurred by Landlord in connection with and properly allocable to
     the management, maintenance, operation and repair of the Building,
     including, without limitation, the costs of maintaining and repairing the
     Common Areas and the Parking Facility, to the extent allocable to the
     Building, easements, property management fees (which fees shall not exceed
     two and one-half percent (2.5%) of Rents billed by Landlord to Tenant for
     the Premises, but excluding Operating Costs (other than Taxes) which are
     billed directly to Tenant by the supplier thereof and are paid by Tenant
     directly to such supplier), expenses for maintenance salaries, fringe
     benefits and related costs for personnel providing building supervisory and
     maintenance services for the Premises at the rank of building manager and
     below, which for such persons also working on properties other than the
     Building and the Land shall be allocated on the basis of the time spent
     working on the Building and the Land, the cost of insurance coverages
     obtained by Landlord, heating and air conditioning costs for Common Areas
     (if any), electricity and other utility costs, the costs of routine repairs
     and maintenance for the Building, landscape maintenance, snow removal,
     Taxes and costs and expenses paid or incurred by Landlord in protesting any
     assessments, valuations, levies or the Taxes which Landlord shall pay or
     become obligated to pay in respect of a fiscal tax year (regardless of when
     such Operating Costs were incurred), the costs of maintaining the Cafeteria
     Space, the costs of maintaining the Fitness Space, the Building's share (as
     reasonably determined by Landlord) of the cost of operating, maintaining
     and repairing any 

                                       20
<PAGE>
 
     areas, facilities or easements which are common to the Building and any
     other properties or buildings sharing common facilities with the Building
     (such as, but not limited to, Parking Facility repair, operation and
     maintenance, snow plowing and removal, landscaping, Common Area and street
     lighting, insurance, taxes, security and management but specifically
     excluding costs, maintenance or repair or Taxes related to Winter Place)
     and amortization of the cost of capital improvements that are (A) made to
     reduce Operating Costs or limit increases therein, to the extent of such
     estimated savings in Operating Costs or to the estimated reduction in
     increases thereto) or (B) required by any applicable Law enacted after the
     date hereof or first interpreted to apply after the date hereof; provided,
     any such amortization or depreciation shall be calculated based on the
     useful life of such improvement and shall utilize a rate of interest that
     is not in excess of two percent over the Prime Rate of interest that is in
     effect as of the date of the completion of such improvements or
     installation.

     Notwithstanding the foregoing, "Operating Costs" shall not include the
following:

     (i)    costs of alterations of other tenants' premises;

     (ii)   any costs that otherwise will be Operating Costs of curing
            construction defects of which Landlord has actual knowledge within
            one (1) year after the Commencement Date;

     (iii)  interest and principal payments on mortgages, and other debt
            costs;

     (iv)   real estate brokers' leasing commissions;

     (v)    attorneys' fees incurred by Landlord in negotiation and enforcement
            of other leases for the Building;

     (vi)   any cost or expenditure (or portion thereof) for which Landlord is
            reimbursed, whether by insurance proceeds or otherwise;

     (vii)  depreciation and amortization of the Building, except as
            otherwise expressly provided herein;

     (viii) anything charged or properly chargeable to Tenant under any other
            provision of this Lease;

     (ix)   costs (including attorneys' fees, fines and penalties) incurred
            solely because Landlord violates any provision of this Lease or any
            provision of Law;

     (x)    any expense for Landlord's employees above the level of building
            manager and any overhead and profit paid to Affiliates of Landlord
            for services, supplies or materials provided to the Building in
            excess of rates that would be competitively available if such
            services, supplies or materials were provided by third parties;

                                       21
<PAGE>
 
     (xi)   advertising or promotional expenditures of any type;

     (xii)  repairs or other work to the extent either actually covered by
            insurance or, if not actually covered, are of a nature which is
            required to be insured against by Landlord in accordance with
            Section 7.1(a) through (f);

     (xiii) costs incurred to test, survey, remediate, contain, abate, remove or
            otherwise remedy Hazardous Substances from the Premises, other than
            such as resulted from Tenant's use, storage, disposal or release of
            Hazardous Substances, including Permitted Activities, and other than
            removal and disposal of Hazardous Substances used in the ordinary
            course of operating and maintaining the Building in accordance with
            applicable Environmental Laws;

     (xiv)  expenses of operating the Common Areas and the Parking Facility
            to the extent not properly allocable to the Premises;

     (xv)   except as otherwise expressly provided herein, any other expenses
            that are not reasonable, actual and necessary out-of-pocket expenses
            (except that Landlord may use its normal accrual method of
            accounting), obtained at competitive prices and directly
            attributable and properly allocable to the operation, maintenance,
            management and repair of the Building as determined under generally
            accepted accounting principles consistently applied; and

     (xvi)  any expenses which, in accordance with generally accepted accounting
            principles, are capital in nature, except as expressly provided
            above.

     Promptly after the Commencement Date and during December of each year or as
soon thereafter as practicable, Landlord shall give Tenant a written notice
consisting of a summary itemization of the services Landlord anticipates will be
included within Operating Costs during the ensuing calendar year, together with
Landlord's estimate of the Operating Costs for such ensuing calendar year.  At
Tenant's request, Landlord shall consult with Tenant concerning the kind and
quality of services to be provided at the Premises and included in Operating
Costs and shall make reasonable efforts to accommodate any reasonable
modification in such services which Tenant requests, provided that Landlord
shall in no event be required to eliminate, add, or modify any such service if
Landlord reasonably determines such elimination, addition or modification will
adversely affect either Landlord's interest in the Land or the Improvements or
Landlord's ability to perform its obligations under this Lease or any other
lease, mortgage or other encumbrance affecting the Land or the Improvements.  If
Landlord makes any changes in services requested by Tenant, Landlord shall
promptly revise its estimate of Operating Costs appropriately for the ensuing
year.

     On or before the first day of each month during the Term after Tenant
receives Landlord's initial estimate of annual Operating Costs, Tenant shall pay
to Landlord as Additional Rent one-twelfth (1/12th) of the estimated annual
amount of Operating Costs according to the latest estimate Tenant has received
from Landlord.   If any time it appears to Landlord that the actual amount of
Operating Costs for the then current calendar year will vary from Landlord's
estimate by

                                       22
<PAGE>
 
more than five percent (5%), Landlord may, by written notice to Tenant, revise
its estimate for such year, and subsequent payments by Tenant for such year
shall be based upon such revised estimate. Within ninety (90) days after the
close of each calendar year or as soon thereafter as practicable, Landlord shall
deliver to Tenant a summary of the total Operating Costs for the previous
calendar year. If such summary shows an amount due from Tenant that is less than
the estimated payments previously paid by Tenant, the amount of such excess
shall be applied as a credit against the installment payments of Operating Costs
that next become due, provided that if such excess occurs at the end of the Term
and Tenant no longer owes any sum to Landlord under this Lease, Landlord shall
promptly refund such excess to Tenant. If such summary shows an amount due from
Tenant that is more than the estimated payments previously paid by Tenant,
Tenant shall pay the deficiency to Landlord, as Additional Rent, within thirty
(30) days after delivery of the summary.

      Section 4.3   Allocation of Taxes.  As of the date of this Lease, the Land
constitutes a single parcel for real estate tax purposes.  A portion of the land
(that underlying 40 Second Avenue as more particularly described in Exhibit A-2
attached hereto, the "Ground Lease Parcel"), is or will be the subject of the
Ground Lease by Landlord to an entity currently affiliated with Landlord.
Landlord agrees to request that the City of Waltham establish separate real
estate tax parcels, or at least separate valuations, for (i) the Ground Lease
Parcel, including 40 Second Avenue and (ii) the balance of the Land, including
the Building.  If, despite such requests, the City of Waltham does not establish
separate real estate tax parcels or valuations as aforesaid, Tenant agrees, and
the Ground Lease shall provide, that real estate taxes for the Land shall be
allocated between the Tenant and the ground lessee in proportion to the relative
Rentable Areas in the Building and in 40 Second Avenue, respectively.

      Further, the Ground Lease will include the right of the ground lessee
(and, derivatively, the occupancy tenants) of 40 Second Avenue and their
employees and invitees to use approximately 230 parking spaces in the Parking
Facility. Pursuant to Section 4.4 hereof, Tenant has the right to use the entire
balance of, or at least 660 parking spaces in the Parking Facility. Accordingly,
Landlord further agrees to request that the City of Waltham, whether or not it
has established separate tax parcels as aforesaid, to establish separate
valuations for (i) 40 Second Avenue and (ii) the Building, to either (a) reflect
such shared rights to use the Parking Facility in establishing the relative
valuations for 40 Second Avenue and the Building, or (b) establish a valuation
for the Parking Facility separate from the valuation of the balance of the Land
and the Building, in which event Landlord and Tenant agree that the Tenant's
share of the real estate taxes for the Parking Facility shall be determined by a
fraction, the numerator of which is 660 (plus the number of parking spaces in
the Parking Facility in excess of 890) and the denominator of which is the
number of parking spaces in the Parking Facility, but not less than 890.

      If, despite Landlord's request, the City of Waltham does not establish a
separate tax parcel or separate valuation for 40 Second Avenue, and the
Building, Landlord and Tenant agree that the real estate taxes allocable to
Tenant for the Building shall be equal to the aggregate fair market value of the
Building and 40 Second Avenue, multiplied by a fraction, the numerator of which
is the fair market value of the Building and the denominator of which is the
aggregate fair market value of the Building and 40 Second Avenue.  In the event
that Landlord, Tenant and, to the extent complementary provisions are included
in the Ground Lease, the ground lessee on its own behalf or 

                                       23
<PAGE>
 
on behalf of any of its occupancy tenants are unable to agree on the fair market
value of each building, Landlord, Tenant or such ground lessee shall have the
right to submit the matter to Arbitration in accordance with Article 20 hereof.

     If the City of Waltham does establish separate real estate tax valuations
for 40 Second Avenue and the Building, but does not establish a separate
valuation for the Parking Facility:

     (i)  if it is evident, from the methodology adopted by the City of Waltham
          in determining such valuations or from abatement proceedings or
          otherwise, that such valuations are based on an income method of
          valuation, then Tenant shall have no right to request a re-allocation
          of the Taxes based on such valuations; or

     (ii) if it is not evident, from the methodology adopted by the City of
          Waltham in determining such valuations or from abatement proceedings
          or otherwise, that such valuations are based on an income method of
          valuation, and Landlord, Tenant or, to the extent complementary
          provisions are included in the Ground Lease, the ground lessee (on its
          own behalf or on behalf of any of its occupancy tenants) determines,
          in good faith, that Tenant or such ground lessee is paying a share of
          the real estate taxes attributable to the Parking Facility on a basis
          that is inconsistent with the agreements herein set forth or that
          reflects an inappropriately high or low valuation for the Parking
          Facility, Landlord, Tenant or such ground lessee shall have the right
          to submit the matter to Arbitration in accordance with Article 20
          hereof. Pending the outcome of any Arbitration, Tenant shall pay such
          amounts as Landlord in its good faith determines Tenant is obligated
          to pay hereunder subject to refund, as appropriate, once a final
          determination issues.

     If Tenant in the exercise of its reasonable judgment believes that Taxes
are excessive and should be abated, Tenant shall have the right to seek an
abatement of the Taxes.  Since Landlord also has the right to seek an abatement,
Landlord or Tenant, as the case may be, shall use reasonable diligence in
pursuing any such abatement, including any settlement thereof; provided,
however, (a) Landlord and Tenant agree to consult with the other prior to
commencing any such abatement; and (b) neither Landlord nor Tenant shall settle
or discontinue prosecution of any such abatement without the approval of the
other, which may be given or withheld in the other's reasonable discretion, but
if such approval is not given, the party seeking such approval shall have the
right to substitute the other party in such proceeding, provided further,
however, that if Tenant wants to settle and Landlord declines, Taxes for the
subject year payable by Tenant hereunder shall not exceed the amount that could
have been payable had such settlement been effected.

     Section 4.4   Parking Facility.  Landlord will make available to Tenant,
on a non-reserved basis, 3.3 parking spaces in the Parking Facility for each
1,000 square feet of Rentable Area of the Premises.  The Parking Facility shall
be provided without charge to Tenant, Tenant's employees and Tenant's invitees
for the use of the Parking Facility, but all costs of operating, maintaining and
repairing said Parking Facility, to the extent reasonably allocable to the
Premises, shall be an Operating Cost.  Landlord and Tenant shall cooperate to
establish reasonable control mechanisms to ensure that such parking spaces are
in fact available to Tenant and that such parking spaces as are

                                       24
<PAGE>
 
to be available in the Parking Facility to the ground lessee, occupancy tenants
and their invitees of 40 Second Avenue are in fact available to them.

      Section 4.5  Right to Audit.  Tenant and its employees, accountants and
consultants, subject to the limitations below, shall have the right, from time
to time (but not more than once each calendar year during the Term), upon
reasonable prior notice, during customary business hours, at its sole cost, and
at Landlord's (or Landlord's property manager's) offices, to examine Landlord's
books and records relating to Operating Costs; provided, any such examination or
audit shall be conducted by employees of Tenant, a nationally or regionally
recognized firm of independent certified public accountants or consultants
retained by Tenant for this purpose, provided that such accountants or
consultants are billing for such services at their normal hourly rates and are
not compensated in whole or in part on a contingent basis, and shall not cover
more than the lesser of (i) the preceding twenty-four month period, or (ii) the
period not previously audited by Tenant (except, however, if Tenant's audit
confirms that Landlord has fraudulently and consistently overcharged Tenant,
such audit may look back for up to four years).  The results of any such audit
shall be kept confidential by Landlord and Tenant, except in the event of any
legal proceeding between Landlord and Tenant.

                                   ARTICLE 5
                           MAINTENANCE AND SERVICES

      Section 5.1   Services Provided by Landlord.  During the Term, Landlord
will operate, maintain and repair the Premises (except for any such operation,
maintenance or repair which is expressly the obligation of Tenant pursuant to
this Lease) in compliance with all applicable Laws and according to those
standards from time to time prevailing for comparable buildings in the area in
which the Premises are located.  Landlord will provide the following services
according to such standards, the costs of which will be included in Operating
Costs to the extent provided in the definition thereof in Section 4.2 (and the
services described in Sections 5.1(b), (c), (d) and (e) below will be available
up to 24 hours per day, seven days per week, excluding Holidays):

     (a)  Landlord's Maintenance Responsibilities.  Landlord shall maintain in
          ---------------------------------------                             
          good repair and condition, all parts of the Common Area, the exterior
          of the Building and all structural elements of the Building, including
          footings, foundation, exterior walls, exterior windows, elevators,
          heating, ventilating and air conditioning equipment, plumbing and
          other major Building systems and roof, but Landlord shall not be
          obligated to replace any equipment which is repairable. "Common Area"
          shall refer to all areas within the outer limits of the Land other
          than the Premises and any other commercial areas intended for renting
          as the same shall exist from time to time, and roads within the outer
          property limits while maintained by any public authority and shall
          include Parking Facility. The Common Area and/or the Building may be
          expanded, contracted or changed by Landlord from time to time as
          deemed desirable by Landlord in its sole discretion; provided, such
          changes shall not materially impair the utility of the Common Area to
          Tenant in connection with Tenant's use of the Premises for the conduct
          of Tenant's intended use of the Premises. With respect to the Common
          Area, Landlord shall regularly mow any grass, remove weeds and

                                       25
<PAGE>
 
          perform general landscape maintenance, and maintain and repair the
          Parking Facility and driveway areas, keeping the same free from an
          unreasonable accumulation of ice and snow. Tenant shall immediately
          give Landlord written notice of any defect or need for such repairs,
          and after receipt of such written notice from Tenant, Landlord shall
          have a reasonable opportunity to repair the same or cure such defect.
          The term "walls", as used in this Section 5.1, shall not include
          Tenant's signage.

     (b)  Electrical Energy.  Six and one-half watts of electrical energy per
          -----------------                                                  
          rentable square foot of the Premises as described in Paragraph 6 of
          Exhibit B, including lighting the Premises and operating Planned
          ---------   
          Office Equipment (as used in this Lease, "Planned Office Equipment"
          means those items of office equipment that the Base Building
          mechanical, electrical and other systems are designed to accommodate
          pursuant to the Base Building Plans). Tenant will not install in the
          Premises any equipment which requires electrical energy or any
          electrical circuits in excess of the energy or circuits available for
          Planned Office Equipment without Landlord's written consent, which
          consent Landlord will not unreasonably withhold. Tenant will pay all
          costs of installing facilities necessary to furnish such excess
          electrical energy for such equipment and for such increased electrical
          energy usage.

     (c)  Heating and Air Conditioning.  Heating, ventilating and air
          ----------------------------                               
          conditioning the Premises at such times and at such temperatures as
          described in Paragraph 5 of Exhibit B. If Tenant installs any
                                      ---------
          machines, equipment or devices in the Premises that do not constitute
          Planned Office Equipment and such machines, equipment or devices cause
          the temperature in any part of the Premises to exceed the temperature
          the Building's mechanical system would be able to maintain in the
          Premises were it not for such machines, equipment or devices, then
          Tenant shall have the right to install supplementary air conditioning
          units to service the Premises. Tenant will pay all costs of
          installing, operating and maintaining such supplementary units (or
          such other air conditioning units and/or air handling equipment
          installed by Tenant); provided, the nature, location and means of
          installing any such equipment shall be subject to Landlord's prior
          written consent, which shall not be unreasonably withheld.

     (d)  Water.  Hot and cold water from the regular Building outlets for
          -----                                                           
          lavatory and restrooms and for drinking purposes including, without
          limitation, the servicing of all lunch rooms, showers and all related
          purposes.  Tenant will not waste water.

     (e)  Access; Passenger Elevator Service.  Access to the Premises and non-
          ----------------------------------                                 
          attended passenger elevator service. Tenant may use only the freight
          elevators, loading docks and entryways Landlord designates for
          loading, unloading, receiving and delivering goods and supplies and
          for disposing garbage or refuse, but such freight elevators, loading
          docks and entryways shall be available for Tenant's use 24 hours per
          day, seven days a week, excluding Holidays. The loading docks are also
          available to 40 Second Avenue on a non-discriminatory basis.

                                       26
<PAGE>
 
     (f) Janitorial.  Reasonable janitorial and cleaning services Monday through
         ----------                                                             
         Friday (except Holidays) after normal business hours in accordance with
         the standards set forth on Exhibit D attached hereto, provided that the
                                    ---------
         Premises are used exclusively for office purposes and are kept
         reasonably in order by Tenant. If the Premises are not used exclusively
         as offices, or if the Tenant elects and Landlord consents, the Premises
         shall be kept clean and in order by Tenant, at Tenant's expense, to the
         satisfaction of Landlord and by persons approved by Landlord; and, in
         all events, Tenant shall pay to Landlord the cost of removal of
         Tenant's refuse and rubbish.

     (g) Damages Caused by Tenant. Tenant shall be responsible for all repairs
         ------------------------                                             
         and replacements to the Premises occasioned by any willful or negligent
         act or omission by Tenant, its agents, administrators and employees or
         by any breach of Tenant's obligations hereunder, except for repairs and
         replacements and losses of such a nature which are required to be
         insured against by Landlord in accordance with Section 7.1(a) through
         (f).

     Section 5.2   Tenant's Maintenance Responsibilities.  Tenant shall, at its
own cost and expense, keep and maintain all parts of the Premises in good repair
and condition, reasonable wear and tear excepted, except those portions that
Landlord is obligated to maintain pursuant to Section 5.1, and shall promptly
make all necessary repairs and replacements to such portions of the Premises,
including, but not limited to, any special entry, interior walls and finish
work, floors and floor coverings, and walls and wall coverings.  Notwithstanding
the foregoing, Tenant shall not be obligated to repair any damage caused by (i)
fire, tornado or other casualty or occurrence to the extent that such damage is
covered by the insurance maintained by Landlord, or (ii) Landlord's failure to
fulfill its maintenance obligations under this Lease.  Tenant shall obtain and
maintain all licenses and permits necessary for the operation of the business
and the use of the Premises by Tenant, except for such licenses and permits
applicable to any general office use, and Tenant's use of the Premises shall be
in compliance with all Laws.

     Section 5.3   Inspection.  Landlord and Landlord's agents and
representatives shall have the right to enter and inspect the Premises at any
reasonable time, after reasonable prior notice (except in the case of
emergency), for the purpose of ascertaining the condition of the Premises, to
make such repairs as may be required or permitted to be made by Landlord under
the terms of this Lease or for any other reasonable purpose, but nothing
contained herein shall be construed as imposing any obligation on Landlord to
make any repairs, alterations or improvements which are Tenant's obligation.
Landlord shall make all reasonable efforts to minimize any interference with
Tenant's use and enjoyment of the Premises which might result from Landlord's
exercise of any rights in this Lease to enter or work in the Premises.

     Section 5.4   Utilities.  Tenant shall contract for in its own name and
directly pay the provider of all water, gas, heat, light, power, telephone,
sewer and sprinkler charges and other utilities and services provided to  the
Premises, together with any taxes, penalties, surcharges or the like pertaining
thereto.  Notwithstanding the foregoing, in the event that such services are not
separately metered, Tenant's responsibility therefore shall be reasonably
estimated by Landlord and

                                       27
<PAGE>
 
payable to Landlord, from time to time, upon Landlord's delivery of a statement
therefore and as Additional Rent hereunder.

      Section 5.5   Interruption of Services.  Except as provided in Article 10
with respect to a casualty or Article 11 with respect to a taking by power of
eminent domain, in the event of any interruption or failure of utility service
or other service required to be furnished by Landlord pursuant to this Article
5, or any  occurrence which poses a legitimate threat to the health or safety of
persons occupying the Premises or otherwise renders the Premises untenantable,
the following provisions shall be applicable: (a) in the event that such
interruption, failure or occurrence continues for a period of in excess of five
consecutive business days, a material portion of the Premises is rendered
untenantable as a result of such interruption, failure or occurrence, and the
repair of the cause of such interruption, failure or occurrence is a matter
within Landlord's reasonable control, then, as Tenant's sole remedy at law or in
equity in connection therewith, Tenant's obligation to pay Rent shall be
equitably abated during the period of such interruption, failure or occurrence;
(b) in the event that such interruption, failure or occurrence continues for a
period of in excess of fifteen consecutive business days and a material portion
of the Premises is rendered untenantable as a result of such interruption,
failure or occurrence, regardless of whether the repair of the cause of such
interruption, failure or occurrence  is a matter within Landlord's reasonable
control, Tenant's obligation to pay Rent shall, as Tenant's sole remedy at law
or in equity in connection therewith, be equitably abated during the period of
such failure or interruption; and (c) in the event that such interruption,
failure or occurrence continues for a period in excess of ninety consecutive
business days and 50% or more of the Premises is rendered untenantable as a
result of such interruption, failure or occurrence, regardless of whether the
repair of the cause of such interruption is a matter within Landlord's
reasonable control, Tenant may, as Tenant's sole remedy at law or in equity in
connection therewith (other than the abatement provided in (a) or (b) above, as
applicable), elect to terminate this Lease by giving written notice to Landlord
at any time prior to the restoration of such services or cure of such
occurrence.

                                   ARTICLE 6
                         ALTERATIONS AND IMPROVEMENTS

      Section 6.1   Procedures for Tenant's Improvements.  Tenant may make any
improvements, alterations, additions or installations in or to the Premises
("Alteration"), except that, without Landlord's prior written consent, which
consent shall not be unreasonably withheld or delayed, Tenant shall not perform
any Alteration which:

      (a)  alters any internal partitions unless Tenant makes all changes to the
           sprinkler, HVAC, lighting, plumbing and security systems necessitated
           thereby;

      (b)  affects any structural component of the Building;

      (c)  has a total cost of $25,000.00 or more as to any Alteration and not
           more than $100,000.00 in the aggregate for all Alterations in any
           calendar year;

      (d)  results in any penetration of the roof membrane.

                                       28
<PAGE>
 
     Along with any request for Landlord's consent and before commencing any
Alteration whether or not requiring Landlord's consent, or delivering or causing
to be delivered to the Premises any materials to be used in connection with the
Alteration, whether or not requiring Landlord's consent, Tenant will provide
Landlord with plans and specifications for the Alteration, the names and
addresses of all contractors and material persons contributing to the
Alteration, copies of all contracts, permits and licenses relating to the
Alteration.  Prior to commencement of any such Alteration, Tenant will deliver
to Landlord certificates issued by insurance companies qualified to do business
in Massachusetts evidencing that workman's compensation, public liability
insurance and builder's risk property insurance (all in amounts, with companies
and on forms reasonably satisfactory to Landlord) are in force and effect and
maintained by all contractors and subcontractors engaged by Tenant to perform
such Alteration.  Tenant agrees to defend and hold Landlord forever harmless
from any and all claims and liabilities of any kind and description which may
arise out of or be connected in any way with any such Alteration.   All
Alterations will be done only by contractors or mechanics reasonably approved by
Landlord.  All Alterations will be performed in such a manner as to avoid labor
disputes and to avoid materially interfering with Landlord's operation of the
Premises.  Tenant will pay the cost of all such Alterations (including a
reasonable charge for Landlord's services and for Landlord's inspection and
engineering time if Landlord reasonably concludes such Alterations will affect
the Building systems, Building structural components or the roof, but no such
charges are payable by Tenant in connection with the Leasehold Improvements to
be installed by Landlord pursuant to the Work Letter), and also the cost of
painting, restoring, or repairing the Premises occasioned by such Alterations.
Upon completing the Alteration, Tenant will furnish Landlord with contractor's
affidavits or unconditional lien releases and full and final waivers of liens,
and receipted bills covering all labor and materials expended and used in
connection with such Alteration.  All Alterations will comply with all insurance
requirements and all Laws and will be constructed in a good and workmanlike
manner.  Tenant will permit Landlord to inspect construction operations in
connection with the Alterations from time to time in Landlord's discretion.

     Section 6.2   Freedom From Liens.  Tenant will keep the Premises free from
any liens arising out of any work performed, material furnished or obligations
incurred by Tenant, and will indemnify Landlord against and protect, defend and
hold Landlord harmless from any liens and encumbrances arising out of any work
performed or material furnished by or at the discretion of Tenant.  In the event
that any such lien is recorded and Tenant shall release such lien of record
within 20 days after the date Tenant has notice of the lien by paying the full
amount of the lien or by posting a bond in an amount equal to the lien.  If
Tenant shall fail to do so, Landlord will have, in addition to all other
remedies provided herein and at law or equity, the right, but not the
obligation, to cause the same to be released by such means as Landlord deems
proper, including paying and/or defending against the claim giving rise to such
lien.  Tenant will pay to Landlord on demand (if such demand is accompanied by
reasonable supporting documentation) and as Additional Rent, any costs Landlord
incurs in connection therewith, including attorneys' fees and costs, together
with interest at the Interest Rate accruing from the date Landlord paid or
incurred such cost(s) until the date Tenant reimburses Landlord for the same.

     Section 6.3   Alterations are Part of the Premises.  Any Alterations of
the Premises (but excluding Tenant's trade fixtures and personal property) will
become at once a part of the Premises 

                                       29
<PAGE>
 
and belong to Landlord without compensation to Tenant. Tenant shall reimburse
Landlord for the cost of removal of all Alterations which, in Landlord's
reasonable judgment, must be removed at the end of the Term in order to permit
subsequent occupancy and are structural in nature or are unusually expensive to
remove, such as interior stairwells or computer flooring and which Landlord
actually removes, provided that, (i) if any such Alteration required Landlord's
consent, Landlord has conditioned its consent to such Alteration upon removal at
the end of the Term, and (ii) Tenant shall not be required to reimburse Landlord
for the cost of removal of the ornamental interior stairway to be included as
part of the initial Leasehold Improvements or, if Tenant elects to install an
additional fire stairway in the location specified in the Base Building Plans,
for the cost of removal of such fire stairs. Tenant shall have no obligation to
reimburse Landlord for the cost of removal of any Alterations except in
accordance with the preceding sentence, but Tenant shall have the right to
remove, prior to the end of the Term, any specialty fixtures installed by
Tenant, such as an emergency generator, supplemental air conditioning units, and
signage, but not including any fixtures or equipment installed by Landlord in
the Cafeteria Space or the Fitness Center as part of the Base Building. The
costs to be borne by Tenant with respect to any removals required or permitted
by this Section 6.3 shall include the cost to repair all damage remaining after
such removals so as to restore the Premises to a condition consistent with the
balance of the Premises, in accordance with all applicable Laws.

                                   ARTICLE 7
                                   INSURANCE

      Section 7.1   Landlord's Insurance.  During the Term, Landlord will
provide and keep in force the following insurance, the costs of which will be
included in Operating Costs:

      (a)  bodily injury and property damage liability insurance relating to
           Landlord's operation of the Premises with a combined single
           occurrence limit of not less than $5,000,000; such insurance will be
           on a commercial general liability form including, without limitation,
           personal injury and assumed contractual liability for the performance
           by Landlord of the indemnity agreements set forth in Section 7.5;
           such liability insurance will include cross liability and
           severability of interests clauses or endorsements; unless otherwise
           approved in writing by Tenant, such policy will have a no deductible
           and will not have a retention or self-insurance provision;

      (b)  all risk property insurance (including fire and standard extended
           coverage perils, leakage from fire protective devices and other water
           damage, vandalism and malicious mischief to the Building and the
           Leasehold Improvements) covering loss or damage to the Improvements
           (including the Base Building, the Leasehold Improvements, and any
           Alterations, but excluding Tenant's fixtures, furnishings, equipment,
           personal property, documents, files and work products) on a full
           replacement cost basis, excluding excavations, footings and
           foundations, and with a deductible not in excess of $50,000 unless
           otherwise approved by Tenant (upon the occurrence of any casualty,
           the amount expended by Landlord to satisfy such deductible will be
           included in Operating Expenses);

                                       30
<PAGE>
 
     (c)  loss of rental income insurance in the amount of not less than one
          year's Base Rent and Additional Rent for Taxes and Operating Expenses;

     (d)  if any boiler or machinery is operated in the Premises and owned by
          Landlord, boiler and machinery insurance;

     (e)  workers' compensation insurance insuring against and satisfying
          Landlord's obligations and liabilities under the workers' compensation
          laws of the State of Massachusetts;

     (f)  if Landlord operates owned, hired or nonowned vehicles on the
          Premises, comprehensive automobile liability will be carried at a
          limit of liability not less than $1,000,000 combined bodily injury and
          property damage; and

     (g)  such other insurance as is then maintained by prudent owners of
          buildings similar to the Building and that Landlord reasonably elects
          to obtain or any Building mortgagee requires.

Insurance effected by Landlord under Sections 7.1(b), (c) and (d) will permit
the release of Tenant from certain liability under Section 7.4.

     Section 7.2   Tenant's Insurance.  After Tenant commences fixturing
pursuant to Section 3.2(a) and during the Term, Tenant will provide and keep in
force the following insurance:

     (a)  bodily injury and property damage liability insurance relating to
          Tenant's business (carried on, in or from the Premises) and Tenant's
          use and occupancy, with a combined single occurrence limit of not less
          than $5,000,000; such insurance will be on a commercial general
          liability form including, without limitation, personal injury and
          assumed contractual liability for the performance by Tenant of the
          indemnity agreements set forth in Section 7.6; Landlord and its
          mortgagee and any property manager designated by Landlord will be
          named as additional insureds in the policy providing such liability
          insurance, which will include cross liability and severability of
          interests clauses or endorsements; unless otherwise approved in
          writing by Landlord, such policy will have no deductible and will not
          have a retention or self-insurance provision;

     (b)  all risk property insurance (including fire and standard extended
          coverage periods, leakage from fire protective devices and other water
          damage) covering loss or damage to Tenant's fixtures, furnishings,
          equipment, personal property, documents, files and work products in
          the Premises on a full replacement cost basis in amounts sufficient to
          prevent Tenant from becoming a coinsurer and with a deductible of
          $5,000 or less;

     (c)  if any boiler or machinery is operated in the Premises and owned by
          Tenant, boiler and machinery insurance;

                                       31
<PAGE>
 
     (d)  workers' compensation insurance insuring against and satisfying
          Tenant's obligations and liabilities under the workers' compensation
          laws of the State of Massachusetts; and

     (e)  if Tenant operates owned, hired or nonowned vehicles on the Premises,
          comprehensive automobile liability will be carried at a limit of
          liability not less than $1,000,000 combined bodily injury and property
          damage.

Insurance effected by Tenant under Sections 7.2(b) and (c) will permit the
release of Landlord from certain liability under Section 7.4.

     Section 7.3   General Insurance Requirements.  All insurance required to
be maintained by Landlord or Tenant pursuant to Sections 7.1 and 7.2 will be
maintained with insurers licensed to do business in the State of Massachusetts
and carrying a rating of A-:X or better according to the latest A.M. Bests
Insurance Reports.  Landlord and Tenant will file with the other, on or before
the earlier of the Commencement Date or the Rent Commencement Date and at least
10 days before the expiration date of expiring policies, certificates of
insurance evidencing the required coverage under Sections 7.1 and 7.2.  If no
objection is made within ten days after receipt of such insurance certificates,
the insurance provided by such certificates shall be deemed to have satisfied
the requirements hereunder regarding the maintenance of insurance.  Such
certificates will indicate that the insurer(s) have agreed to give the other
party at least 30 days notice prior to any cancellation of, or material
modification to, the required coverage.  Landlord and Tenant will cooperate with
each other in the collection of any insurance proceeds which may be payable in
the event of any loss, including the execution and delivery of any proof of loss
or other actions required to effect recovery. All commercial general liability
and property policies required to be maintained by either party hereunder will
be written as primary policies, not contributing with and not supplemental to
any coverage that the other party may carry.

     Section 7.4   Waivers.  Except to the extent caused by the willful or
negligent act or omission or breach of this Lease by Landlord or anyone for whom
Landlord is legally responsible, Landlord and its Affiliates will not be liable
or in any way responsible for, and Tenant waives all claims against Landlord and
its Affiliates for, any loss, injury or damage suffered by Tenant or others
relating to (a) loss or theft of, or damage to, property of Tenant or others;
(b) injury or damage to persons or property resulting from fire, explosion,
falling plaster, escaping steam or gas, electricity, water, rain or snow, or
leaks from any part of the Improvements or from any pipes, appliances or
plumbing, or from dampness; or (c) damage caused by persons on or about the
Premises, or caused by the public or by construction of any private or public
work.  Landlord and its Affiliates will not be liable or in any way responsible
to Tenant for, and Tenant waives all claims against Landlord and its Affiliates
for, any loss, injury or damage that is insured or required to be insured by
Tenant under Sections 7.2(b) or (c), and for purposes of such waiver   Tenant
will be deemed to be "required to insure" the amount of any deductible permitted
by, or the amount self-insured by Tenant pursuant to, such sections.  Tenant and
its Affiliates will not be liable or in any way responsible to Landlord for, and
Landlord waives all claims against Tenant and its Affiliates for, any loss,
injury or damage that is required to be insured against by Landlord in
accordance with Sections 7.1(b), (c) or (d).

                                       32
<PAGE>
 
      Section 7.5   Landlord's Indemnification.  Subject to Section 7.4 and
except to the extent caused by the willful or negligent act or omission or
breach of this Lease by Tenant or anyone for whom Tenant is legally responsible,
Landlord will indemnify and hold Tenant harmless from and against any and all
liability, loss, claims, demands, damages or expenses (including reasonable
attorneys' fees) due to or arising out of any willful or negligent act or
omission or breach of this Lease by Landlord or anyone for whom Landlord is
legally responsible.  Landlord's obligations under this Section 7.5 will survive
the expiration or early termination of the Term.

      Section 7.6   Tenant's Indemnification.  Subject to Section 7.4 and except
to the extent caused by the willful or negligent act or omission or breach of
this Lease by Landlord or anyone for whom Landlord is legally responsible,
Tenant will indemnify and hold Landlord harmless from and against any and all
liability, loss, claims, demands, damages or expenses (including reasonable
attorneys' fees) due to or arising out of any accident or occurrence on or about
the Premises during the Term (including, without limitation, accidents or
occurrences resulting in injury, death, property damage or theft) or any willful
or negligent act or omission of or breach of this Lease by Tenant or anyone for
whom Tenant is legally responsible.  Tenant's obligations under this Section 7.6
will survive the expiration or early termination of the Term.

                                   ARTICLE 8
                      CERTAIN RIGHTS RESERVED BY LANDLORD

      Section 8.1   Rights Reserved by Landlord.  Landlord reserves the
following rights, which rights Landlord may exercise subject to provisions of
Section 5.3 without liability to Tenant; without effecting an eviction,
constructive or actual, or a disturbance of Tenant's use or possession of the
Premises; and without giving rise to any claim for setoff or abatement of Rent:

      (a)  Make Repairs.  To repair the Premises or any part thereof, and to 
           ------------ 
           enter upon the Premises for such purposes. Landlord may temporarily
           close doors, entryways, public spaces, elevators and corridors in the
           Premises and interrupt or temporarily suspend services and facilities
           in connection with such work.

      (b)  Regulate Heavy Equipment.  To approve the weight, size and location
           ------------------------  
           of safes and other heavy equipment and articles in and about the
           Premises and the manner in which Tenant moves such heavy equipment
           and articles into and out of the Premises.

      (c)  Rules and Regulations.  To adopt reasonable rules and regulations
           ---------------------                                            
           governing Tenant's use of the Premises, the Common Areas and any
           enclosed walkways or Parking Facility attached or adjacent to the
           Building, provided that such rules and regulations will not conflict
           with the terms and conditions of this Lease.

      (d)  Landlord Control.  Landlord will have the right to close any portion
           ----------------                                                     
           of the Building or Land to the extent as may, in Landlord's
           reasonable opinion, be necessary to prevent a dedication thereof or
           the accrual of any rights to any person or the public therein.
           Landlord will at all times have full control, management and
           direction of the 

                                       33
<PAGE>
 
         Premises, subject to the rights of Tenant under this Lease. No implied
         easements are granted by this Lease.

      Section 8.2   Emergency Entry.  Subject to provisions of Section 5.3,
Landlord and its agents may enter the Premises at any time in case of emergency
and may use any and all means which Landlord may deem proper to open the doors
to the Premises during an emergency. Landlord's entry into the Premises in the
event of an emergency will not, under any circumstances, be construed or deemed
to be a forcible or unlawful entry into, or detainer of, the Premises, or to be
an eviction of Tenant from the Premises or any portion thereof.

      Section 8.3   Exhibition of Premises.  Subject to provisions of Section
5.3, Tenant will permit Landlord and its agents to enter and pass through the
Premises or any part thereof at reasonable times during normal business hours
to: (a) post notices of nonresponsibility; (b) exhibit the Premises to
Landlord's mortgagees and lienholders and to prospective purchasers or
mortgagees of the Premises; and (c) during the period commencing eighteen months
prior to the expiration of the Term, exhibit the Premises to prospective tenants
of the Premises.


                                   ARTICLE 9
                           ASSIGNMENT AND SUBLETTING

      Section 9.1   Assignment and Subletting.  Tenant shall not have the right
to assign or pledge this Lease or to sublet the whole or any part of the
Premises, whether voluntarily or by operation of law, or permit the use or
occupancy of the Premises by anyone other than Tenant, without the prior written
consent of Landlord.  Landlord's consent shall not be unreasonably withheld or
delayed beyond a period of fifteen days; provided, in addition to any other
grounds for denial, Landlord's consent shall be deemed reasonably withheld if,
in Landlord's good faith judgment: (i) the proposed assignee or subtenant does
not have the financial strength to perform its obligations under this Lease or
any proposed sublease, taking into account the fact that Tenant remains liable
for the obligations of such assignee or subtenant; (ii) the proposed assignee or
subtenant intends to use any part of the Premises for a purpose other than
general office uses, which term shall include offices  for use by medical
professionals and their staff, and offices for persons or entities whose primary
business consists of the delivery or administration of health services, except
that no portion of the Premises shall be used as a medical clinic, surgical
center, treatment facility, diagnostic center, radiology practice or other
facility where medical patients are diagnosed or treated by medical or health
care professionals, except as provided in Section 9.2; (iii) either the proposed
assignee or subtenant, or any person which directly or indirectly controls, is
controlled by, or is under common control with the proposed assignee or
subtenant, occupies space in the Building, or is negotiating with Landlord to
lease space in the Building; (iv) under applicable zoning the proposed use of
the Premises or the Building by the proposed assignee or subtenant would require
in excess of 3.3 parking spaces per 1000 square feet of Net Rentable Area of
such assigned or subleased space; or (v) the proposed assignee fails to execute
an assumption agreement with Landlord that is reasonable in form.
Notwithstanding any permitted assignment or subletting, Tenant shall at all
times remain directly, primarily and fully responsible and liable for the
payment of the Rent herein specified and for compliance with all of its other
obligations under the terms, 

                                       34
<PAGE>
 
provisions and covenants of this Lease throughout the Term. Upon the occurrence
of an Event of Default, if the Premises, or any part thereof, are then assigned
or sublet, Landlord, in addition to any other remedies herein provided or
provided by Law, may, at its option, collect directly from such assignee or
subtenant rents due and becoming due to Tenant under such assignment or sublease
and apply such rent against any sums due to Landlord from Tenant hereunder, and
no such collection shall be construed to constitute a novation or release of
Tenant from the further performance of Tenant's obligations hereunder.

     (a)  Notice to Landlord.  In the event Tenant desires to sublet the
          ------------------                                            
          Premises, or any portion thereof, or assign this Lease, Tenant shall
          give written notice thereof to Landlord at least thirty (30) days
          prior to the proposed commencement date of such subletting or
          assignment, which notice shall set forth the name of the proposed
          subtenant or assignee, all relevant terms of any sublease or
          assignment and copies of financial reports and other relevant
          information reasonably requested by Landlord concerning the proposed
          subtenant or assignee.

     (b)  Allocation of "Profits" and Expenses.  In the event Landlord consents
          ------------------------------------                                 
          to any assignment or subletting proposed by Tenant, all sums or other
          economic consideration received by Tenant in connection with such
          assignment or subletting, whether denominated as rent or otherwise,
          which exceeds, in the aggregate, the "Total Tenant Costs" shall be
          allocated between Landlord and Tenant as follows without affecting or
          reducing any other obligation of Tenant hereunder: (i) Tenant shall be
          entitled to retain the entirety of such excess until Tenant has
          recovered all Total Tenant Costs; (ii) Tenant shall be entitled to
          retain the entirety of such excess to the extent it accrues with
          respect to the period prior to the expiration of the fifth Lease Year
          of this Lease; and (iii) Landlord and Tenant shall each be entitled to
          50% of any such excess that accrues after the expiration of said fifth
          Lease Year.  If Tenant is receiving such sublease rents or rents from
          its assignee directly, Tenant shall pay to Landlord its share of such
          excess upon Tenant's receipt of such rents, from time to time, and as
          Additional Rent hereunder.  For purposes hereof, the phrase "Total
          Tenant Costs" shall be defined as the sum of the following: (i) the
          total amount of Rent, including all Operating Costs and all other
          items of Additional Rent, which Tenant is obligated to pay Landlord
          under this Lease (prorated to reflect obligations allocable to less
          than all of the Premises under a sublease), plus (ii) the "Tenant
          Transaction Costs."  For purposes hereof, the phrase "Tenant
          Transaction Costs" shall be defined as the aggregate reasonable and
          necessary costs incurred by Tenant in such assignment or subletting
          including, without limitation, broker's commissions, and costs of
          alterations and redecorating.  For purposes of calculating the Total
          Tenant Costs in determining the amount of any Additional Rent payable
          by Tenant under this paragraph during the term of any such assignment
          or subletting, no interest shall accrue on any portion of Total Tenant
          Costs.  The Additional Rent, if any, payable by Tenant under this
          paragraph shall be payable in monthly installments, or otherwise as
          the same becomes due, pursuant to the provisions of each respective
          assignment or sublease.  In addition, if Landlord grants its consent
          to any sublease or assignment, Tenant shall pay all of the attorney's
          fees

                                       35
<PAGE>
 
          of Landlord reasonably incurred with respect to such assignment
          or sublease.  If Tenant has any options to extend the term of this
          Lease, such options shall not be available to any subtenant or
          assignee, directly or indirectly.

     (c)  Recapture.  In addition to, but not in limitation of, Landlord's right
          ---------                                                             
          to approve any subtenant or assignee, Landlord shall have the option,
          in its sole discretion, (i) in the event of a proposed assignment of
          the Premises (other than as an assignment to an assignee permitted by
          Section 9.1), to recapture the lease and (ii) in the event of any
          proposed subletting which together with all other then effective
          sublettings of the Premises is in the aggregate more than 30% of the
          Premises (not including in such calculation of the Rentable Area so
          sublet the Rentable Area assigned or sublet to a transferee permitted
          by Section 9.1(d)), but less than the entire Premises and that is
          proposed to commence after the expiration of the fifth Lease Year, to
          recapture the portion of the Premises to be sublet, as of the date the
          subletting is to be effective. The option shall be exercised, if at
          all, by Landlord giving Tenant written notice thereof within thirty
          (30) days following Landlord's receipt of Tenant's written notice as
          required above.  If Landlord recaptures a portion of the Premises
          under this subparagraph, the parties shall cooperate in the execution
          and delivery of an amendment that is reasonable in form and that
          memorializes the occurrence and effect of such recapture.  Landlord
          shall not have the right pursuant to this subparagraph (c) to
          recapture any space with respect to which the applicable sublease
          commenced prior to the expiration of the fifth Lease Year, even though
          such sublease may continue by its terms after the expiration of such
          fifth Lease Year.

     (d)  Tenant's Affiliate Transfer.  Notwithstanding any contrary provision
          ---------------------------   
          of this Lease, Tenant may without the prior consent of Landlord, at
          any time assign or otherwise transfer this Lease or sublease any
          portion of the Premises to any parent, subsidiary or affiliate
          corporation or entity, or any corporation resulting from the
          consolidation or merger of Tenant into or with any other entity, or to
          any person, firm, entity or corporation acquiring a majority of
          Tenant's issued and outstanding capital stock or substantially all of
          Tenant's physical assets; provided, however, the following terms and
          conditions shall be applicable in connection with any such assignment
          or transfer: (a) the use of the Premises shall remain substantially
          unaffected; (b) the assignee shall assume in writing the terms and
          conditions set forth herein to be observed and performed by Tenant in
          an instrument to which Landlord is a party or is expressly designated
          as an intended third party beneficiary; and (c) no such merger or
          consolidation shall be completed by Tenant unless the successor entity
          formed thereby shall have a consolidated net worth at least equal to
          the consolidated net worth of Tenant according to Tenant's last annual
          audited financial statement. As used herein, the expression "affiliate
          corporation or entity" means a person or business entity, corporate or
          otherwise, that directly or indirectly through one or more
          intermediaries, controls or is controlled by, or is under common
          control with, another. The word "control" means the right and power to
          direct or cause the direction of the management and policies of a
          person or business entity, corporate or otherwise, through ownership
          or voting securities or by contract. Nothing herein contained shall be
          construed as releasing Tenant from any of its liabilities or other
          obligations hereunder.

                                       36
<PAGE>
 
      Section 9.2   Massachusetts General Sublease.  Tenant acknowledges that
Landlord has an obligation to make up to 3,500 square feet of Rentable Area of
the Premises available to Massachusetts General Physicians Organization, Inc.
("MGP") pursuant to the terms of Exhibit F. Tenant hereby agrees to sublease a
portion of the Premises to MGP pursuant to a sublease (the "Sublease") in
accordance with the terms of Exhibit F, the terms of this Section 9.2, and, to
the extent not inconsistent with the terms of Exhibit F and this Section 9.2, on
substantially the same terms and conditions as the lease from Waltham 40 LLC to
MGP for space in the building at 40 Second Avenue (the "40 Second Avenue
Lease").

     The Sublease will be negotiated by Landlord with MGP and will be prepared
by Landlord's attorney, the cost of such attorney to be paid by Landlord.  Any
reasonable costs incurred by Tenant for its attorney to review such Sublease
shall be paid by Landlord.  The terms of the Sublease will be subject to
Tenant's approval, which approval shall not be unreasonably withheld or delayed.

     Landlord and Tenant agree that MGP's premises in the Building under the
Sublease (the "Sublease Space") will be on the first floor of the Premises in a
suitable location designated by Tenant.

     The term of the Sublease, including all options to extend, shall be
coterminous with the term and extension options of the 40 Second Avenue Lease,
and the Sublease shall provide that: (i) MGP may exercise its options to extend
the term of the Sublease so long as it also extends the term of the 40 Second
Avenue Lease, and (ii) the term of the Sublease shall terminate upon the
expiration or sooner termination of the 40 Second Avenue Lease.

     The annual net rental payable by MGP under the Sublease will be $22.00 per
rentable square foot net during the initial term of the Sublease.  In the event
that MGP extends the Sublease, Tenant will not be obliged to pay Landlord as
rent for the Sublease Space, during any extension term of the Sublease, any more
money than is received by Tenant as rent under the MGP Sublease.

     Landlord will construct the Sublease Space in accordance with the terms of
the Sublease. Landlord will provide to MGP a buildout allowance of $23.00 per
rentable square foot for the Sublease Space and the amount provided by Landlord
to MGP will reduce the Leasehold Improvements Allowance provided by Landlord to
Tenant under Exhibit C of this Lease.  Tenant will not be obligated to
contribute to the buildout for MGP.

     In the event that Associated Radiologists of Boston, Inc. ("ARB") or its
assignee shall terminate its lease in the building at 40 Second Avenue (the "ARB
Lease"), or if the ARB Lease is terminated for any reason, or if the ARB Lease
is amended or modified in such a manner that the owner of the building at 40
Second Avenue shall no longer be precluded by the ARB Lease from leasing of any
other space in the building at 40 Second Avenue for the operation of a radiology
practice, then Landlord will use reasonable efforts to relocate MGP to the
building at 40 Second Avenue, provided that Landlord shall have no obligation to
so relocate MGP if the cost to Landlord

                                       37
<PAGE>
 
of such relocation will exceed $50,000. Tenant agrees that the Sublease shall
not obligate MGP to relocate to the 40 Second Avenue Building and agrees that
Landlord shall have no further obligation or liability if MGP does not agree to
a relocation.

     At such time as MGP shall surrender the Sublease Space, Tenant agrees to
accept the Sublease Space in its then "as is condition" subject to the
obligation of MGP to surrender such space in accordance with the terms of the
Sublease, and provided that, in any event, Landlord will cause to be removed any
special conditions or equipment associated with the use of the Sublease Space
for a radiology practice.

     Landlord will cause Waltham 40 LLC, the landlord of the building at 40
Second Avenue, to agree to be bound by the terms of this Section 9.2.

                                  ARTICLE 10
                       DAMAGE BY FIRE OR OTHER CASUALTY

      Section 10.1  Termination Options.  If the Premises are damaged by fire or
other casualty, Landlord will, within 30 days of the date of such damage, notify
Tenant in writing of the time necessary to repair or restore such damage, as
estimated by Landlord's architect, engineer or contractor.  If (i) such damage
occurs during the 12-month period that ends on the last day of the initial Term,
if Tenant has not exercised its Extension Option, or during the last twelve
months of the Extension Term, if Tenant has exercised its Extension Option, and
if such estimate states that repair or restoration of all of such damage that
was caused to the Premises cannot be completed within 180 days from the date of
such repair or restoration is commenced, or (ii) the loss is of a nature which
Landlord is not required by this Lease to insure against, then both Tenant and
Landlord will have, as their respective sole remedies in connection with such
condition, the option to terminate this Lease.  If such damage is of a nature
which is not required to be insured against by Landlord in accordance with
Section 7.1(a) through (f) and if the cost to repair such damage is determined
to be in excess of $500,000.00 then Landlord will have the option to terminate
this Lease.  Any option to terminate granted above must be exercised by written
notice to the other party given within 10 days after Landlord delivers to Tenant
the notice of estimated repair time.  If either party exercises its option to
terminate this Lease, the Term will expire and this Lease will terminate 10 days
after notice of termination is delivered; provided, however, that Rent for the
period commencing on the date of such damage until the date this Lease
terminates will be reduced to the reasonable value of any use or occupation of
the Premises by Tenant during such period.

      Section 10.2  Repair Obligations.  If the Premises are damaged by fire or
other casualty and neither party terminates this Lease according to Section
10.1, then Landlord will repair and restore such damage with reasonable
promptness, subject to delays for insurance adjustments and delays caused by
matters beyond Landlord's control.  Landlord will have no liability to Tenant
and Tenant will not be entitled to terminate this lease if such repairs and
restoration are not in fact completed within the estimated time period, provided
that Landlord promptly commences and diligently pursues such repairs and
restoration to completion; provided, however, that if Landlord fails to complete
such repairs and restoration within 270 days (which period shall not be extended
by any Permitted Delays) from the date of the casualty, Tenant's sole remedy
shall be to terminate this Lease by notice to Landlord given prior to such
completion.  In no event will Landlord be 

                                       38
<PAGE>
 
obligated to repair, restore or replace any of the property by reason of any
damage which is of a nature which is required to be insured against by Tenant in
accordance with Section 7.2.

      Section 10.3  Rent Abatement.  If any fire or casualty damage renders the
Premises untenantable and if this Lease is not terminated according to Section
10.1, then Rent will abate beginning on the date of such damage.  Such abatement
will end on the date Landlord has substantially completed the repairs and
restoration Landlord is required to perform according to Section 10.2.  Such
abatement will be in an amount bearing the same ratio to the total amount of
Rent for such period as the untenantable portion of the Premises bears to the
entire Premises.  In no event will Landlord be liable for any inconvenience or
annoyance to Tenant or injury to the business of Tenant resulting in any way
from damage; provided, however, that, to the extent Tenant remains in possession
of a portion of the Premises, Landlord will take all reasonable steps to
minimize the disruption to Tenant's business and use of such portion of the
Premises during the period of repair.

                                  ARTICLE 11
                                EMINENT DOMAIN

      Section 11.1  Termination.  If the whole of the Premises is taken by any
public authority under the power of eminent domain, this Lease will terminate as
of the day possession is taken by such public authority.  If more than 15% of
the Rentable Area of the Building is taken, or if so much of the Land is taken
that Tenant is permanently deprived of the use of more than 25% of the Parking
Facility previously available on the Land (and such spaces cannot be
reconstructed on the remaining Land or any adjacent land acquired by Landlord
for that purpose within 90 days after Tenant is so deprived of such use), by any
public authority under the power of eminent domain, then Tenant may, by notice
to Landlord, terminate this Lease as of the day possession is taken by such
public authority.  In case of any such termination, Landlord will make a pro
rata refund of any prepaid Rent.

      Section 11.2  Award; Restoration.  All damages awarded for such taking
under the power of eminent domain or any like proceedings will belong to and be
the property of Landlord.  Tenant hereby assigns to Landlord its interest, if
any, in such award, except that Tenant will have the right to prove in any
condemnation proceedings and to receive any award which may be made for
relocation benefits and moving expenses.  Anything in this Article 11 to the
contrary notwithstanding, in the event of a partial condemnation of the Premises
where this Lease is not terminated, (i) Landlord will, at its sole cost and
expense, restore the Premises (other than any alterations or improvements
installed by Tenant) to a complete architectural unit (but Landlord's
restoration obligations will be limited to restoration and repair of the Base
Building and Leasehold Improvements and Landlord will not be obligated to
commence any restoration if the cost of such restoration is in excess of the
condemnation award available to Landlord), and (ii) the Base Rent provided for
herein during the period from and after the date of delivery of possession
pursuant to such proceedings to the termination of this Lease will be reduced to
a sum equal to the product of the Base Rent provided for herein multiplied by a
fraction, the numerator of which is the fair market rent of the Premises after
such taking and after the same has been restored to a complete architectural
unit, and the denominator of which is the fair market rent of the Premises prior
to such taking.

                                       39
<PAGE>
 
                                  ARTICLE 12
                             SURRENDER OF PREMISES

      Section 12.1  Surrender of Possession.  On the last day of the Term, or on
the earlier termination of this Lease, Tenant will peaceably surrender the
Premises in good order, condition and repair consistent with Tenant's duty to
make repairs as provided in this Lease.  On or before the last day of the Term,
or on the earlier termination of this Lease, Tenant will, at its sole cost and
expense, remove all of its property and trade fixtures and equipment from the
Premises and patch any holes in the walls, floor or ceiling that remain as a
consequence of such removal.  Subject to Section 6.3, all alterations, additions
and fixtures, other than Tenant's trade fixtures and equipment which have been
made or installed by either Landlord or Tenant upon the Premises, will remain
the property of Landlord and will be surrendered with the Premises as a part
thereof.  Upon the expiration of the Term or earlier termination of this Lease,
Tenant will promptly surrender all keys for the Premises to Landlord at the
place then fixed for the payment of Rent and will provide Landlord with
combinations to any vaults, locks and safes left on the Premises.

      Section 12.2  Holding Over.  Tenant will, at the expiration or earlier
termination of this Lease, yield up immediate possession of the Premises to
Landlord.  If Tenant retains possession of the Premises, or any part thereof
after such termination, then Landlord may, at its option, serve written notice
upon Tenant that such holding over constitutes the creation of a month to month
tenancy upon the terms and conditions set forth in this Lease; provided,
however, that the monthly Base Rent shall, in addition to all other sums which
are to be paid by Tenant hereunder, whether or not as Additional Rent, be equal
to 150% of the Base Rent being paid monthly to Landlord under this Lease
immediately prior to such termination.

                                  ARTICLE 13
                                QUIET ENJOYMENT

      Section 13.1  Quiet Enjoyment.  Landlord represents and warrants that it
has full right and authority to enter into this Lease and that Tenant, while
paying the rental and performing its other covenants and agreements herein set
forth, shall peaceably and quietly have, hold and enjoy the Premises for the
Term without hindrance or molestation from Landlord or any person or entity
claiming by, through, or under Landlord, subject to the terms and provisions of
this Lease.

                                  ARTICLE 14
                              DEFAULT AND REMEDIES

      Section 14.1  Events of Default.  The following events shall be deemed to
be events of default by Tenant under this Lease (individually, an "Event of
Default" and collectively, "Events of Default"):

     (a) Base Rent and Operating Costs.  Tenant shall fail to pay any monthly
         -----------------------------                                       
     installment of Base Rent or Operating Costs when due, and such failure
     shall continue for a period of five (5) days after notice from Landlord;
     provided, if Tenant is late in the payment of any such monthly installment
     more than three times during the Term, thereafter Landlord may require
     Tenant to pay such monthly installments via wire transfer;

                                       40
<PAGE>
 
     (b) Other Monetary Defaults.  Tenant shall fail to pay any Rent, other than
         -----------------------                                                
     a monthly installment of Base Rent or Operating Costs, on or before the
     first day of the next calendar month after the month in which Tenant
     receives notice of such other Rent, if Tenant receives such notice on or
     before the tenth day of the calendar month, or on or before the first day
     of the second calendar month after the month in which Tenant receives such
     notice if Tenant receives such notice after the tenth day of the month;

     (c) Liens.  Tenant shall fail to discharge any lien placed upon the
         -----                                                          
     Premises in violation of Section 6.2 within (20) days after Tenant receives
     notice that any such lien or encumbrance is filed against the Premises; or

     (d) Other Breach.  Tenant shall fail to comply with any term, provision or
         ------------                                                          
     covenant of this Lease (other than the foregoing in this Article 14), and
     shall not cure such failure within thirty (30) days after notice; provided,
     in the event such default cannot reasonably be cured within such thirty
     (30) day period, an Event of Default shall not be deemed to have occurred
     so long as Tenant commences an effective cure within said thirty (30) day
     period and prosecutes such cure diligently to completion.

      Section 14.2  Remedies.  Upon the occurrence of any of such Events of
Default, Landlord, at its option, shall have one or more of the following
described remedies:

     (a) Termination.  Landlord may terminate this Lease and Landlord may, at
         -----------                                                         
     Landlord's option, enter into the Premises, remove Tenant's signs and other
     evidences of tenancy, and take and hold possession thereof, without such
     termination, entry and possession releasing Tenant, in whole or in part,
     from its obligations hereunder, including Tenant's obligation to pay Base
     Rent, Operating Costs and all other sums payable by Tenant hereunder, for
     the full Term.   Landlord shall use reasonable efforts to relet the
     Premises for such rent and upon such terms as Landlord shall reasonably
     determine (including, without limitation, the right to relet the Premises
     as part of a larger area and the right to change the character or the use
     made of the Premises), and Landlord shall not be required to accept any
     tenant offered by Tenant or to observe any instructions given by Tenant
     about such reletting or to accept any lease which Landlord reasonably
     determines is not consistent with the then existing market or is not
     approved by Landlord's mortgagee.  In any such case, Landlord may make
     repairs, alterations and additions in or to the Premises, and redecorate
     the same to the extent Landlord reasonably deems necessary or desirable.
     All rentals and other sums received by Landlord from any such reletting
     shall be applied as follows:  first, to the payment of any amounts, other
     than Rent, due hereunder from Tenant to Landlord; second, to the payment of
     any costs and expenses of such alterations, repairs, additions and
     redecorating; third, to the payment of Landlord's expenses of reletting,
     including, without limitation, broker's commissions, attorneys' fees and
     lease inducements, such as moving or leasehold improvement allowances and
     unexpired free rent periods; fourth, to the payment of Rent and other
     charges due and unpaid hereunder; and the residue, if any, shall be held by
     Landlord and applied in payment of future Rent as the same may become due
     and payable hereunder.  If such rentals and other sums received from such
     reletting during any month be less than the

                                       41
<PAGE>
 
     Rent to be paid during said month by Tenant hereunder, Tenant shall pay
     such deficiency to Landlord. Such deficiency shall be calculated and paid
     monthly. Notwithstanding any such termination and collection by Landlord of
     Rent from Tenant for a portion of the remaining Term, Landlord may at any
     time elect to seek damages as provided in (b) below.

     (b) Damages in the Event of Termination.  It is acknowledged that the
         -----------------------------------                              
     damages that would be incurred by Landlord in connection with the
     termination of this Lease following a default by Tenant would be difficult
     to estimate or ascertain. Notwithstanding any contrary provision herein, in
     the event Landlord elects to terminate this Lease and re-enter and take
     possession of  the Premises, Landlord may, provided that any action to
     recover such damages pursuant to this Section 14.2(b) is commenced by
     Landlord within twelve (12) months following termination of this Lease
     pursuant to Section 14.1(a), in lieu of continuing to collect Rent from
     Tenant for the remainder of the Term under (a) above, recover from Tenant,
     as liquidated damages, an amount equal to the sum of the following:  (i)
     all unpaid Rent that is then payable by Tenant hereunder; plus (ii) a sum
     of money equal to the difference between the (A) entire amount of Rent that
     would be thereafter payable under the Lease and ending upon the original
     date of the expiration of the Term, less (B) the fair market rent for the
     Premises for the same period, which difference (if positive) shall be
     immediately due and payable upon demand but which shall be discounted to
     present value using a discount rate equal to the discount rate of the
     Federal Reserve Bank of Boston as of the date of calculation plus two
     percent (2%).   For purposes of calculating the amount of Rent that would
     be payable under the Lease for any future period, the Base Rent shall be
     computed as provided in Section 4.1 and the Additional Rent component of
     the Rent shall be computed on the basis of the average monthly amount of
     Rent accruing during the twenty-four (24) month period immediately
     preceding the default to which such termination relates (exclusive of any
     months in which Tenant received abated rent or in which the tax parcel upon
     which the Land is situated was not fully assessed for the value of the
     Building); provided, however, if the default occurs prior to the expiration
     of the first twenty-four (24) months of the Lease, then the Rent shall be
     computed on the basis of the average monthly amount of Rent accruing during
     all months preceding the month in which said default occurred (exclusive of
     any months in which Tenant received abated rent or in which the tax parcel
     upon which the Land is situated was not fully assessed for the value of the
     Building).

     (c) Tenant's Property.  Any personal property of Tenant remaining in the
         -----------------                                                   
     Premises after the expiration or earlier termination of the Lease or of
     Tenant's right to possession of the Premises shall be deemed abandoned.
     Any and all such abandoned property may be handled, removed and stored, as
     the case may be, by or at the direction of Landlord at the sole risk, cost
     and expense of Tenant, and Landlord shall in no event be responsible for
     the value, preservation or safekeeping thereof.  Tenant shall pay to
     Landlord, upon demand, any and all expenses incurred in such removal and
     all storage charges against such property so long as the property shall be
     in Landlord's possession or under Landlord's control.  Any such property of
     Tenant not retaken by Tenant from storage within thirty (30) days after
     removal from the Premises shall, at Landlord's option, be deemed conveyed
     by Tenant to Landlord under this Lease as by a bill of sale without further
     payment or credit by Landlord to Tenant.

                                       42
<PAGE>
 
     (d) Late Charge.  In the event Tenant fails to pay any portion of the Rent
         -----------                                                           
     payable by Tenant hereunder within five (5) days of the date that such
     amount is due, Tenant shall pay to Landlord on demand a late charge to help
     defray the additional cost to Landlord for processing such late payments in
     an amount equal to (i) so long as Tenant has not been late in the payment
     of any element of Rent more than two times during the preceding twelve (12)
     month period, interest on such installment or other charge from the date
     such installment or charge was due at a per annum rate equal to the
     Interest Rate until paid in full, or (ii) after Tenant has been late in the
     payment of any element of Rent more than three times during the preceding
     twelve (12) month period, five percent (5%) of such installment or other
     charge that is so overdue in any month, and two percent (2%) each month
     thereafter until paid in full.  Such late charge shall be Additional Rent
     hereunder and the failure to pay such late charge within five (5) days
     after demand therefor shall be an Event of Default hereunder. The provision
     for such late charge shall be in addition to all of Landlord's other rights
     and remedies hereunder and shall not be construed as liquidated damages or
     as limiting Landlord's remedies in any manner.

     (e) Consequential Damages.  In no event shall Tenant be liable for any
         ---------------------                                             
     indirect, incidental, special, punitive or consequential damages, including
     lost profit or revenues, even if informed of their possibility.

     (f) Miscellaneous.  Pursuit of any of the foregoing remedies shall not
         -------------                                                     
     preclude pursuit of any of the remedies herein provided or any other
     remedies available at law or in equity, nor shall pursuit of any remedy
     herein provided constitute a forfeiture or waiver of any Rent due to
     Landlord hereunder or of any damages accruing to the non-breaching party by
     reason of the violation of any term, provision and/or covenant herein
     contained.  No agreement to accept a surrender by Tenant of its right or
     possession of the Premises shall be valid unless in writing signed by
     Landlord. No waiver by either party of any violation or breach of any term,
     provision and/or covenant herein contained shall be deemed or construed to
     constitute a waiver of any other violation or breach of any term, provision
     and/or covenant herein contained. Landlord's acceptance of the payment of
     rental or other payments hereunder after the occurrence of an Event of
     Default shall not be construed as a waiver of such default, unless Landlord
     so notifies Tenant in writing.  Forbearance by either party to enforce one
     or more of the remedies with respect to any default shall not constitute a
     waiver thereof, or a waiver of any remedy in connection with any subsequent
     default, unless such waiver is acknowledged in writing.  In the event of
     any litigation to enforce or interpret the terms hereof, the prevailing
     party shall be entitled to an award of its reasonable attorneys' fees and
     disbursements.

      Section 14.3  Landlord's Default.  In the event of any default by
Landlord, Tenant will give Landlord written notice specifying the default with
particularity, and Landlord shall thereupon

                                       43
<PAGE>
 
have thirty (30) days in which to cure any such default; provided, in the event
such default cannot reasonably be cured within such thirty (30) day period, an
event of default shall not be deemed to have occurred so long as Landlord
commences an effective cure within said thirty (30) day period and prosecutes
such cure diligently to completion. If Landlord shall fail to cure such default
as provided in the preceding sentence, or if, in the event of an emergency
condition affecting safety, the operation of major Building systems or otherwise
materially affecting Tenant's use and enjoyment of the Premises, Landlord does
not promptly commence and diligently pursue such cure, Tenant will be entitled
to exercise any right or remedy available to Tenant at law or in equity by
reason of such default except to the extent expressly waived or limited by the
terms of this Lease, and, provided that Tenant stated in such notice of default
to Landlord that Tenant intends to effect its self-help rights under this
Section 14.3, Tenant may proceed to cure Landlord's default and commence an
action against Landlord to recover the amount reasonably expended by Tenant in
doing so, plus interest thereon at the Interest Rate from the date incurred to
the date of payment by Landlord. Notwithstanding any contrary provision herein,
if Landlord shall fail to perform any covenant, term or condition of this Lease
required to be performed by Landlord, if any, and if as a consequence of such
default Tenant shall recover a money judgment against Landlord, such judgment
shall be satisfied only out of (i) installments of Rent then or thereafter due
to Landlord, or (ii) the proceeds of sale received upon execution of such
judgment and levied thereon against the right, title and interest of Landlord in
the Building and out of rents or other income from such property receivable by
Landlord, or out of the consideration received by Landlord from the sale or
other disposition of all or any part of Landlord's right, title and interest in
the Building, but subject to the rights of any Mortgagee, as hereinafter
defined, and neither Landlord nor any officer, agent, trustee, beneficiary or
general or limited partner of Landlord, or other person or entity having an
interest in Landlord shall be personally liable for any deficiency; provided,
the foregoing shall not limit any right that Tenant might have to obtain
injunctive relief against Landlord or to maintain any suit or action in
connection with the enforcement or collection of damages to the extent that such
damages are payable under policies of liability insurance maintained by
Landlord. Notwithstanding the foregoing, however, if Tenant has been notified of
the name and address of any mortgagee, ground lessor, trust deed holder, and/or
sale-leaseback lessor of Landlord's interest in the Premises ("Mortgagee"), then
Tenant will not exercise any remedy as a result of Landlord's default unless and
until Tenant has given any such Mortgagee, by registered or certified mail, a
copy of any notice of default served upon Landlord simultaneously with the
delivery of notice to Landlord. Any disputes as to the availability or exercise
of Tenant's self-help rights under this Section shall be subject to Arbitration
pursuant to Article 20 hereof.

     In no event shall Landlord be liable for any indirect, incidental, special,
punitive or consequential damages, including lost profit or revenues, even if
informed of their possibility.

      Section 14.4  Legal Costs.  The prevailing party in any action commenced
under this Lease will be entitled to recover from the non-prevailing party the
prevailing party's attorneys' fees and costs.

                                       44
<PAGE>
 
                                  ARTICLE 15
                                 SUBORDINATION

      Section 15.1  Mortgages.  Tenant accepts this Lease subject and
subordinate to any ground lease and mortgage(s) now or at any time hereafter
constituting  a lien or charge upon the Building and the Land or the Premises;
provided, however, that if the holder of any such mortgage elects to have
Tenant's interest in this Lease superior to any such instrument, then, by notice
to Tenant from such holder, this Lease shall be deemed superior to such lien,
whether this Lease was executed before or after said mortgage.  Tenant shall at
any time hereafter on demand execute any instruments, releases or other
documents that may be reasonably required by any mortgagee for the purpose of
subjecting and subordinating this Lease to the lien of any such mortgage;
provided, it shall be a condition to Tenant's obligation to subordinate to any
future mortgage encumbering the Building that Tenant receives an agreement from
the holder of any such mortgage that, in the event that such holder acquires the
Landlord's interest in the Building, such holder shall recognize the validity of
this Lease so long as Tenant is not in default hereunder beyond any applicable
cure periods, subject to the limitations in Section 15.2.

      Section 15.2  Attornment.  If Landlord's interest in the Premises is
transferred to any person or entity ("Transferee") as a result of the
foreclosure of a mortgage or deed of trust encumbering the Premises or the
termination of a ground lease of the Premises or other proceedings for the
enforcement of a mortgage, deed of trust or ground lease or by taking a deed in
lieu of foreclosure or otherwise, Tenant will not disaffirm this Lease or any of
its obligations under this Lease and Tenant will, unless otherwise notified in
writing by Transferee, immediately and automatically attorn to Transferee and
this Lease will continue in full force and effect as a direct lease between
Tenant and Transferee upon the same terms and conditions of this Lease except
that Transferee will not be (a) subject to any offsets or defenses which Tenant
might have against Landlord, other than those expressly provided for in this
Lease; (b) bound by any prepayment by Tenant of more than one month's
installment Rent; or (c) obligated to perform any of Landlord's obligations
under this Lease except during the period of Transferee's ownership of the
Premises. Tenant's right of first offer pursuant to Section 2.4 shall be binding
upon any Transferee.

      Section 15.3  Tenant's Notice of Default.  Provided the Landlord or any
Mortgagee which has notified Tenant in writing (by the way of a notice of
assignment of lease or otherwise) of its address, Tenant will give such
Mortgagee, a copy of any notice of default which Tenant delivers to Landlord and
based upon which Tenant asserts the right to an abatement of any Rent or to
terminate this Lease, simultaneously with Tenant's delivery of the notice to
Landlord, by registered or certified mail, return receipt requested.  Any such
Mortgagee will have the right to cure any alleged default during the same period
that Landlord has to cure such default and if such Mortgagee cures such alleged
default, the Mortgagee's performance will be deemed performance on behalf of
Landlord and the performance will be accepted by Tenant as if performed by
Landlord. Tenant shall not be entitled to any abatement of Rent or to terminate
this Lease until Tenant has delivered a copy of the relevant notice or notices
to any Mortgagee or Mortgagees pursuant to this Section 15.3 and afforded such
Mortgagee or Mortgagees the cure rights provided for in this Section 15.3.

      Section 15.4  Estoppel Certificates.  Tenant agrees from time to time upon
not less than 10 days' prior written request by Landlord to deliver to Landlord
a statement in writing certifying

                                       45
<PAGE>
 
(a) that the form of the Lease attached to such certificate is a true and
correct copy of this Lease, (b) that this Lease is unmodified and in full force
and effect (or if there have been modifications that the Lease as modified is in
full force and effect and stating that the modifications have been attached to
the certificate); (c) Tenant is in possession of the Premises and Rent is
accruing under the Lease in accordance with the terms hereof (or, if not,
indicating the status); (d) the dates to which the Rent and other charges have
been paid; (e) to Tenant's knowledge, neither Landlord nor Tenant is in default
in any provision of this Lease or, if in default, the nature thereof specified
in detail; (f) the amount of monthly rental currently payable by Tenant; (g) the
amount of any prepaid Rent, (h) that Tenant has accepted the Premises in its
then current condition (or if there is Landlord's Work not yet completed stating
the nature of such Work, to Tenant's knowledge) and Landlord has no further
obligation to provide any tenant inducements (or if there is any remaining
tenant inducement not yet provided, stating the nature thereof, to Tenant's
knowledge), and (i) such other matters as may be reasonably requested by
Landlord or any Mortgagee or prospective purchaser of the Premises. If Tenant
does not deliver such statement to Landlord within such 10 day period, and
Landlord delivers a notice to Tenant advising it of its failure to respond
within such 10 day period, and Tenant further fails to deliver such statement to
Landlord within five days after receiving such follow-up notice, Landlord and
any prospective purchaser or Mortgagee of the Premises may conclusively presume
the truth of and rely upon the following facts: (i) that the terms and
provisions of this Lease have not been changed except as otherwise represented
by Landlord; (ii) that this Lease has not been canceled or terminated and is in
full force and effect, except as otherwise represented by Landlord; (iii) that
the current amounts of the Base Rent are as represented by Landlord; (iv) that
there have been no subleases or assignments of the Lease; (v) that not more than
one month's Base Rent or other charges have been paid in advance; (vi) that
Tenant has accepted the Premises in its current condition; and (vii) that
Landlord is not in default under the Lease. In such event, Tenant will be
estopped from denying the truth of such facts.

     Landlord agrees from time to time upon not less than 10 days' prior written
request by Tenant to deliver to Tenant a statement in writing certifying (a)
that this Lease is unmodified and in full force and effect (or if there have
been modifications that the Lease as modified is in full force and effect and
stating the modifications); (b) the dates to which the Rent and other charges
have been paid; (c) to Landlord's knowledge, Tenant is not in default in any
provision of this Lease or, if in default, the nature thereof specified in
detail; (d) the amount of monthly rental currently payable by Tenant; (e) the
amount of any prepaid Rent, and (f) such other matters as may be reasonably
requested by Tenant, any prospective sublessee of the Premises, assignee of this
Lease or purchaser of Tenant's business.  If Landlord does not deliver such
statement to Tenant within such 10 day period, and Tenant delivers a notice to
Landlord advising it of its failure to respond within such 10 day period, and
Landlord further fails to deliver such statement to Tenant within five days
after receiving such follow-up notice, Tenant and any prospective sublessee or
assignee or purchaser of Tenant's business may conclusively presume the truth of
and rely upon the following facts: (i) that the terms and provisions of this
Lease have not been changed except as otherwise represented by Tenant; (ii) that
this Lease has not been canceled or terminated and is in full force and effect,
except as otherwise represented by Tenant; (iii) that the current amounts of the
Base Rent are as represented by Tenant; (iv) that not more than one month's Base
Rent or other charges have been paid in advance; and (v) that Tenant is not in
default under the Lease.  In such event, Landlord will be estopped from denying
the truth of such facts.

                                       46
<PAGE>
 
                                  ARTICLE 16
                               USE AND COMPLIANCE

      Section 16.1  Permitted Use.  Tenant covenants to use the Premises only
for general office purposes and information technology consulting services and
placement, which use shall also include offices for medical professionals and
their staff and offices for persons or entities whose primary business consists
of the delivery or administration of health services, except that no portion of
the Premises shall be used as a medical clinic, surgical center, treatment
facility, diagnostic center, radiology or other facility where medical patients
are diagnosed or treated by medical or health care professionals, except as
provided in Section 9.2.  Tenant will not keep anything on or about the Premises
which would invalidate any insurance policy required to be carried on the
Premises by Landlord or Tenant pursuant to this Lease, unless such insurance can
be kept in force by endorsement and Tenant agrees to pay, as Additional Rent,
the additional premium for such endorsement.  Tenant will not place a load upon
any floor of the Premises exceeding the floor load per square foot area set
forth in the Base Building Plans and Paragraph 1 of Exhibit B.
                                                    --------- 

      Section 16.2  Compliance with Laws and Recorded Covenants.  Tenant will
not use the Premises or permit anything to be done in or about the Premises
which will, in any way, conflict with any Laws now in force or which may
hereafter be enacted or promulgated.  Except where this Lease makes Landlord
responsible for compliance with Laws applicable to office uses generally, Tenant
will, at its sole cost and expense, promptly comply with all Laws now in force
or which may hereafter be in force, and with the requirements of any fire
insurance underwriters or other similar body now or hereafter constituted
relating to or affecting Tenant's use or occupancy of the Premises or the
condition of any portion of the Premises which Tenant is obligated to maintain
pursuant to Section 10.1.  Landlord represents that all recorded covenants,
conditions, and restrictions affecting the Premises as of the date of this Lease
(the "Existing Encumbrances") are referred to in the schedules attached as
Exhibit E.  Tenant will not do anything to violate or cause Landlord to be in
---------                                                                    
violation of the Existing Encumbrances.  Landlord may hereafter enter into any
easements, covenants, conditions, and restrictions affecting the Premises and
may enter into or amend the Ground Lease (including granting to the ground
lessee and tenants and occupants of 40 Second Avenue the right to use up to 230
parking spaces in the Parking Facility, but not in any event more than the
number of spaces by which the total number in the Parking Facility exceeds the
number of spaces to which Tenant is entitled pursuant to Section 4.4 hereof),
create a condominium upon the Premises and 40 Second Avenue, or subdivide any
parcel or parcels of land which may include the Premises with Tenant's consent,
which consent shall not be unreasonably withheld, so long as such actions which
do not materially impair any of Tenant's rights or materially increase any of
Tenant's obligations under this Lease ("Future Encumbrances").  Tenant shall
also, upon receiving a copy of any Future Encumbrance, comply with such Future
Encumbrances to the extent that doing so will not materially impair any of
Tenant's rights or obligations under this Lease.  Except with respect to any
Alterations or other work installed or to be installed in the Premises by
Tenant, Landlord represents that when possession of all of the Premises is
tendered to Tenant with the Landlord's Work Substantially Completed, the
Premises will comply in all material respects with all applicable Laws in effect
on the date of this Lease.

      Section 16.3  Landlord's Covenants.  To the best of Landlord's actual and
not constructive knowledge, as of the Commencement Date the Building (including
the Premises and all common 

                                       47
<PAGE>
 
areas) shall be free of all Hazardous Substances that are not in compliance with
applicable Environmental Laws. Upon request of Tenant, Landlord shall provide
Tenant a copy of whatever environmental reports or assessments concerning the
Land or Building that may be in Landlord's possession or under Landlord's
control. In the event that, during the Term, Tenant discovers the existence in
the Premises or the Building of Hazardous Substances other than those handled by
Tenant, handled by a sublessee of Tenant or other party that has occupied any
portion of the Premises after acquiring all or any portion of Tenant's rights
hereunder, or handled by another tenant or other occupant of the Building
subsequent to the Commencement Date, and if such Hazardous Substances have not
been handled in compliance with all applicable Environmental Laws (such
hazardous materials, that have not been handled in compliance with all
applicable Environmental Laws being defined as "Building Unlawful Hazardous
Materials"), then Landlord shall, as its sole obligation and responsibility to
Tenant, (a) commence within sixty (60) days after Landlord receives from Tenant
notice of such breach or discovery, as the case may be, and verifies the
accuracy of such claim by Tenant, a removal, encapsulation or other containment
program reasonably elected by Landlord which is required by and complies with
applicable Laws, and (b) diligently prosecute such program to completion,
including any required monitoring or reporting activities, in such a manner as
will make the Premises free from Building Unlawful Hazardous Materials in
accordance with the standards promulgated in applicable Environmental Laws.
Notwithstanding the foregoing, Landlord shall indemnify Tenant from and against
any claim made by, or liabilities or judgments owed to, third parties to the
extent that the damages forming the basis thereof are caused by the presence,
now or hereafter, of any Hazardous Substances that have been placed, stored or
generated in the Premises by Landlord and, to the extent that Landlord is so
obligated to indemnify Tenant, Landlord's duty of indemnification shall survive
the termination of the Lease.

      Section 16.4  Tenant's Covenants.  Tenant shall at all times comply, and
cause its subtenants, contractors, employees and agents to comply, with
applicable local, state and federal laws, ordinances and regulations relating to
Hazardous Substances.  "Hazardous Substances" means (1) any oil, flammable
substances, explosives, radioactive materials, hazardous wastes or substances,
toxic wastes or substances or any other wastes, materials or pollutants that (A)
pose a hazard to the Premises, Building or Land or to persons on or about the
Premises, Building or Land or (B) cause the Premises, Building or Land to be in
violation of any hazardous materials Laws; (2) asbestos in any form which is or
could become friable, urea formaldehyde foam insulation, transformers or other
equipment that contains dielectric fluid containing polychlorinated biphenyls,
or radon gas; (3) any chemical, materials or substance defined as or included in
the definition of "hazardous substances", "hazardous wastes", "hazardous
materials", "extremely hazardous waste", "restricted hazardous waste", or "toxic
substances", or words of similar import under any applicable Environmental Law;
(4) any other chemical, material or substance, exposure to which is prohibited,
limited or regulated by any governmental authority or may or could pose a hazard
to the health and safety of the occupants of the Premises, Building or Land or
the owners and/or occupants of property adjacent to or surrounding the Land, or
any other person or entity coming upon the Land or adjacent property; and (5)
any other chemical, material or substance that may or could pose a hazard to the
environment.  Tenant shall not: (i) use the Premises, Building or Land for the
storage of Hazardous Substances except for such activities that are part of the
course of Tenant's ordinary business (the "Permitted Activities"); provided,
such Permitted Activities are conducted in accordance with all applicable
Environmental Laws, and have been approved in advance in writing by Landlord;
(ii) use the Premises, Building or Land as a landfill or dump; or (iii) install
any underground tanks of any 

                                       48
<PAGE>
 
type at the Land. Tenant shall at its own expense maintain in effect any and all
permits, licenses or other governmental approvals, if any, required for Tenant's
use of the Premises and require the same of any subtenants. Tenant shall make
and cause any subtenant to make all disclosures required of Tenant by any Laws,
and shall comply and cause subtenant to comply with all orders concerning
Tenant's use of the Premises issued by any governmental authority having
jurisdiction over the Premises and take all action required by such governmental
authorities to bring the Tenant's activities on the Premises into compliance
with all environmental and other Laws affecting the Premises. If at any time
Tenant shall become aware, or have reasonable cause to believe, that any
Hazardous Substance has been released or has otherwise come to be located on or
beneath the Land, Tenant shall, give written notice of that condition to
Landlord. Tenant shall be responsible for, and shall indemnify, defend and hold
Landlord harmless from and against, all environmental claims, demands, damages
and liabilities, including, without limitation, court costs and reasonable
attorneys' fees, if any, arising out, or in connection with the generation,
storage, disposal or other presence of any Hazardous Substance in, on or about
the Premises, Building or Land that occurred during the Term and that was caused
or permitted by Tenant or its subtenants, contractors, agents or employees. The
indemnification provided by this Paragraph shall survive the expiration or
earlier termination of this Lease. Tenant shall be entitled to control any
regulatory or other proceedings for which Tenant is responsible under this
Section 16.4, including the right to contest in good faith any at no risk to
Landlord any potentially applicable statutes, regulations, or other governmental
determinations, provided that Landlord shall at all times have the right to join
in and/or be notified of the status of any such proceedings.

                                  ARTICLE 17
                                   CAFETERIA

      Section 17.1  Cafeteria.  Landlord shall furnish and equip a full service
cafeteria in a certain space (the "Cafeteria Space") of approximately 3,000
square feet of Rentable Area in the location to be specified in the Base
Building Plans, in accordance with the Preliminary Plans and the Cafeteria Plan
to be prepared by Landlord consistent with the Preliminary Plans and approved by
Tenant.  Tenant shall enter into a contract with the operator selected by
Tenant, acting with input from and consultation with Landlord.   The initial
cost of constructing, furnishing, and equipping such Cafeteria Space in
accordance with the Preliminary Plans and the Cafeteria Plan to be prepared by
Landlord and approved by Tenant shall be included as part of the Base Building.
The Cafeteria Space shall be included in the calculation of the number of square
feet of Rentable Area in the Premises.   In addition, and notwithstanding any
contrary provision herein, all costs incurred by Landlord in connection with
such cafeteria including, without limitation, utilities, janitorial and repairs
and maintenance of furniture, fixtures and equipment shall be included as part
of Operating Costs.  Tenant shall be responsible for all costs incurred in
connection with any Alteration to the Cafeteria and any operating losses in
connection herewith.  No failure of performance on the part of any operator of
the cafeteria within the Cafeteria Space shall constitute a default by Landlord
under the Lease.  Tenant may change the operator of the Cafeteria at any time
and at Tenant's cost; Tenant shall consult with Landlord in good faith to
replace such operator with an alternative qualified food service vendor.  Tenant
may discontinue operation of the Cafeteria Space at any time and use the
Cafeteria Space for other purposes permitted hereby, but on the expiration or
termination of the Lease, the Cafeteria Space and all equipment installed
therein by Landlord as part of the Base Building (or replacements thereto) shall
be surrendered to Landlord in accordance with Section 12.1.

                                       49
<PAGE>
 
                                  ARTICLE 18
                                 FITNESS SPACE

      Section 18.1  Fitness Space.  Landlord shall construct or install a
fitness room complete with showers and lockers in a certain space (the "Fitness
Space") of approximately 2,000 square feet of Rentable Area in a location in the
Building to be specified in the Base Building Plans in accordance with the
Preliminary Plans and the Fitness Plan to be prepared by Landlord in accordance
with the Preliminary Plans and approved by Tenant.  The initial cost of
constructing the Fitness Space in accordance with the Preliminary Plans and the
Fitness Space Plan to be prepared by Landlord consistent with the Preliminary
Plans and approved by Tenant shall be included as part of the Base Building;
provided, Tenant shall be solely responsible for installing exercise equipment
therein and managing the Fitness Space.  The Fitness Space shall be included in
the calculation of the number of square feet of Rentable Area in the Premises.
In addition, and notwithstanding any contrary provision herein, all costs
incurred by Landlord in connection with such Fitness Space including, without
limitation, redecorating, janitorial, repairs and maintenance of fixtures and
equipment and utilities, shall be included as part of Operating Costs.  Such
fitness equipment shall be owned by Tenant and may be removed by Tenant upon
expiration or termination of the Lease. Tenant may discontinue operation of the
Fitness Space at any time and use the Fitness Space for other purposes permitted
hereby, but on the expiration or termination of this Lease, the Fitness Space
and all the equipment installed therein by Landlord as part of the Base Building
(or replacements thereto) shall be surrendered to Landlord in accordance with
Section 12.1.

                                  ARTICLE 19
                                TENANT'S SIGNAGE

Tenant shall have the right to purchase, install or replace, at Tenant's sole
cost and expense (except as set forth below with respect to the "Signage
Allowance"), certain signage (the "Building Signage") that depicts the trade
name and/or mark of the business being conducted and that shall be mounted in a
location approved by Landlord (which approval will not be unreasonably withheld)
on the exterior of the Building; provided, Tenant's right to install and replace
the Building Signage shall be subject to the following terms and conditions:

     (a)  Tenant shall, at its sole cost, obtain and maintain in full force and
          effect all requisite governmental permits and approvals for the
          installation, maintenance and replacement of such Building Signage
          (collectively, the "Municipal Approvals"), and acknowledges that
          Landlord does not represent that any such approvals shall be
          forthcoming.

     (b)  Prior to the installation and replacement of any such Building
          Signage, Tenant shall deliver notice to Landlord (the "Signage
          Notice") certifying that all requisite governmental approvals have
          been obtained and including plans and specifications, that designate
          the design, size, color, composition, method of illumination, if any,
          and method and timing of installation of the Building Signage.

     (c)  The plans and specifications included in the Signage Notice shall be
          subject to Landlord's written consent, which consent shall not be
          unreasonably withheld.

                                       50
<PAGE>
 
     (d)  The design, construction, installation and operation of all such
          Building Signage (and all necessary structural supports)  shall be
          performed by Tenant at Tenant's sole cost and expense and in
          accordance with the plans and specifications that have been approved
          by Landlord in writing.

     (e)  Tenant shall, at its sole cost, maintain all such Building Signage and
          associated wiring in a first class condition and shall perform all
          repairs and replacement reasonably necessary to maintain compliance
          with such standard.

     (f)  Tenant shall, at its sole cost, repair any damage to the Building
          caused by the installation, maintenance, operation or replacement of
          such Building Signage, including, with limitation, water leaks or
          other problems occasioned by any penetration of the exterior shell of
          the Building, all at Tenant's sole cost and expense.

     (g)  Tenant shall, at its sole cost, obtain and keep in full force and
          effect any and all licenses, permits and other governmental approvals
          which are or may become required for the operation and use of such
          Building Signage.

     (h)  Tenant shall assume all risk of any damage to such Building Signage.

     (i)  Upon the expiration or earlier termination of the Lease, Tenant shall
          remove the Building Signage and associated wiring and hardware visible
          from the inside or outside of the Building, return the Building to the
          condition that existed prior to the installation thereof and repair
          and restore any damage resulting from, or remaining after, such
          removal, all at Tenant's sole cost and expense, and all in accordance
          with all applicable Laws, including, but not limited to, all
          applicable Laws regarding the removal of electrical wiring.

     (j)  Landlord shall provide to Tenant an allowance (the "Signage 
          Allowance") in an amount of $15,000.00 to fund the cost of the
          Building Signage and Tenant's building directory signage. Payment of
          the Signage Allowance shall be made by Landlord to Tenant within
          thirty (30) days of the satisfaction of the following conditions: (i)
          the Rent Commencement Date has occurred, Tenant is in occupancy of the
          Premises in the routine conduct of its business and no event of
          default exists with respect to Tenant's obligation to pay Rent; and
          (ii) Landlord has received full lien waivers from all contractors
          supplying labor and materials in connection with the Building Signage.

     (k)  Notwithstanding the foregoing, Tenant's right to maintain the Building
          Signage shall terminate and be of no further force and effect upon the
          earlier to occur of: (i) the expiration or termination of this Lease;
          (ii) the termination of Tenant's right to possession of the Premises;
          or (iii) the date Tenant conducts its business in a manner that
          Landlord reasonably deems to be disreputable. In the event of the
          termination of Tenant's right to maintain such signage, Tenant shall
          remove the signage that is the subject of such termination, return the
          portion of the Building to which the signage was affixed to the
          condition that existed prior to the installation thereof and repair
          and restore any damage resulting from, or remaining after, such
          removal, all at Tenant's sole cost and expense.

                                       51
<PAGE>
 
     (l)  Landlord shall not permit the installation of any signage on the
          exterior of the building other than the foregoing Tenant Building
          Signage; provided, this restriction shall not be applicable with
          respect to any signage identifying the name of the Building or with
          respect to any monument or similar ground level signage and, provided
          further, this restriction shall be deemed terminated upon any
          termination of Tenant's right to maintain the Tenant Signage.

Landlord shall not place, or permit to be placed, any signage on the exterior of
the Building identifying any person or business other than Tenant, provided that
Landlord shall be permitted to place signs on the exterior of the Building
relating to the Parking Facility, traffic movement, building address or other
informational signage.

                                   ARTICLE 20
                                  ARBITRATION

      Section 20.1  Arbitration.

     (a)  Landlord and Tenant agree that Arbitration will be used to resolve any
          dispute with respect to the following:

          (i)   any disputes arising with respect to Landlord's and Tenant's
                obligations under Article 3 or the Work Letter;

          (ii)  Any disputes relating to the determination of Operating Costs
                allocable to the Premises, subject to the limitations in 
                Section 4.3;

          (iii) any disputes relating to the granting, withholding or delay
                of any consent or approval which is specifically provided to 
                be not unreasonably withheld;

          (iv)  any disputes regarding the proper allocation of Taxes to Tenant
                in accordance with Section 4.7 hereof; and

          (v)   any other provision in this Lease which specifically provides 
                for Arbitration.

     (b)  When any issue is to be resolved by Arbitration, Landlord and Tenant
          shall initially meet and attempt to agree upon the matter in question.
          If they have been unable to so agree within the time period specified
          as to such matter under this Lease, or, if no such time period is
          specified, within thirty (30) days, then, at the request of either
          party the matter will be determined by an arbitration board as
          provided in this Article 20. Except as provided in subsection (d)
          below, such arbitration will be conducted in Boston in accordance with
          the Accelerated Commercial Arbitration Rules of the American
          Arbitration Association. Within thirty (30) days after their
          appointment, the arbitrators so chosen shall hold a hearing at which
          each party may submit

                                       52
<PAGE>
 
          evidence, be heard and cross-examine witnesses, with each party having
          at least ten (10) days' advance notice of the hearing. The decision of
          the arbitrators will be final, binding and non-appealable and judgment
          thereupon may be rendered and enforced in any court having
          jurisdiction thereof. Except where specifically provided otherwise in
          this Lease, the arbitrator will be instructed to award costs to the
          prevailing party; otherwise each party shall bear its own expenses in
          connection with the Arbitration and the costs of its arbitrator, and
          the cost of the third arbitrator shall be shared equally by Landlord
          and Tenant. The costs of all counsel, experts and other
          representatives that are retained by a party will be paid by such
          party.

     (c)  The arbitration board shall consist of three (3) reputable real estate
          professionals with experience with first-class high rise office
          buildings in the Boston, Massachusetts metropolitan area. Each party
          shall appoint one (1) arbitrator who shall have no material financial
          or business interest in common with the party making the selection and
          shall not have been employed by such party for a period of three (3)
          years prior to the date of selection. If the first two arbitrators are
          unable to agree on a third arbitrator within thirty (30) days after
          the appointment of the second arbitrator, or if either party refuses
          or neglects to appoint an arbitrator as herein provided within twenty
          (20) days after the appointment of the first arbitrator, then such
          third arbitrator or such second arbitrator whose appointment was not
          made as aforesaid shall be appointed by the American Arbitration
          Association.

     (d)  The decision of any two (2) of the three (3) arbitrators will control;
          if neither of the arbitrators selected by Landlord or Tenant agree
          with each other or with the independent arbitrator, the decision of
          the independent arbitrator will control; and such decision will be
          made and delivered to Landlord and Tenant by such arbitrators not
          later than the thirtieth (30th) day following the hearing provided for
          in subsection (a) above.

                                  ARTICLE 21
                                 MISCELLANEOUS
                                        
      Section 21.1  Personal Property Taxes.  Tenant shall be liable for all
taxes levied or assessed against personal property, furniture or fixtures owned
by Tenant or placed by Tenant on, in or at the Premises or otherwise arising out
of the use or occupancy of the Premises.  If any such taxes for which Tenant is
liable are levied or assessed against Landlord or Landlord's property and if
Landlord elects to pay the same, or if the assessed value of Landlord's property
is increased by inclusion of such personal property, furniture or fixtures
placed by Tenant on, in or at the Premises, and Landlord elects to pay the taxes
based on such increase, Tenant shall pay to Landlord upon demand that portion of
such taxes.

      Section 21.2  Notices.  All bills, statements, notices or communications,
including changes of address of either party, which either party may desire or
be required to give to the other shall be deemed sufficiently given or rendered
if in writing and either delivered to the other party personally, sent by
registered or certified mail, return receipt requested, or sent prepaid by
nationally recognized air courier service, addressed to either party at the
Notice Address designated in Section 1.1.  The 

                                       53
<PAGE>
 
time of rendition thereof or the giving of such notice or communication shall be
deemed to be the time when the same is personally delivered to the other party,
deposited in the mail, or delivered to the other party by a national air courier
service as herein provided. Any notice or the return of any access cards, keys,
or otherwise to be given from Tenant to Landlord must be delivered in the manner
set forth above.

      Section 21.3  Interpretation.  Words of any gender used in this Lease
shall be held and construed to include any other gender, and words in the
singular number shall be held to include the plural, unless the context
otherwise requires.  This Lease is intended to be construed in accordance with
the law of the Commonwealth of Massachusetts.  If this Lease is ever construed
by a court of law, such court shall not construe this Lease or any provision
hereof against any party as drafter.

      Section 21.4  Successors and Assigns.  The terms, provisions and covenants
and conditions contained in this Lease shall apply to, inure to the benefit of,
and be binding upon, the parties hereto and upon their respective heirs, legal
representatives, successors and permitted assigns, except as otherwise herein
expressly provided.  Landlord shall have the right to assign any of its rights
and obligations under this Lease.  The term "Landlord" shall mean only the
owner, from time to time, of fee title to the Premises, and in the event of the
transfer by such owner of its interest in the Premises, Landlord's grantee or
Landlord's successor shall, upon such transfer, become "Landlord" hereunder,
thereby freeing and relieving the grantor or assignor of all covenants and
obligations of "Landlord" hereunder thereafter accruing, but such covenants and
obligations shall be binding during the term of this Lease upon each new owner
for the duration of such owner's ownership.  The term "Tenant" shall include
Renaissance Worldwide, Inc. and its respective permitted successors and assigns.
Tenant agrees to furnish promptly upon demand, a corporate resolution, proof of
due authorization by partners, or other appropriate documentation evidencing the
due authorization of Tenant to enter into this Lease.  Nothing herein contained
shall give any other tenant in the Building any enforceable rights either
against Landlord or Tenant as a result of the covenants and obligations of
either party set forth herein.

      Section 21.5  Captions.  The captions inserted in this Lease are for
convenience only and in no way define, limit or otherwise describe the scope of
the intent of this Lease, or any provision hereof, or in any way affect the
interpretation of this Lease.

      Section 21.6  Amendments.  This Lease constitutes the entire agreement of
the parties with respect to its subject matter and may not be altered, changed
or amended except by an instrument in writing signed by both parties hereto.

      Section 21.7  Survival.  All obligations of Landlord and Tenant hereunder
not fully performed as of the expiration or earlier termination of the Lease
Term shall survive the expiration or earlier termination of the Term, including,
without limitation, all payment obligations with respect to Operating Costs and
all obligations concerning the condition of the Premises.  Upon the expiration
or earlier termination of the Term, Tenant shall pay to Landlord the amount, as
estimated by Landlord, necessary (i) to repair and restore the Premises as
provided herein; and (ii) to discharge Tenant's obligation for Operating Costs
or other amounts due Landlord.  All such amounts shall be used and held by
Landlord for payment of such obligations of Tenant, with Tenant being held
liable for any additional costs upon demand by Landlord, or with any excess to
be returned to Tenant after 

                                       54
<PAGE>
 
all such obligations have been determined and satisfied. Any security deposit
held by Landlord shall be credited against the amount payable by Tenant under
this subparagraph.

      Section 21.8  Severability.  If any clause or provision of this Lease is
illegal, invalid or unenforceable under present or future Laws effective during
the Term, then, and in that event, it is the intention of the parties hereto
that the remainder of this Lease shall be not affected thereby, and it is also
the intention of the parties to this Lease that in lieu of each clause or
provision of this Lease that is illegal, invalid or unenforceable, there be
added as a part of this Lease a clause or provision as similar in terms of such
illegal, invalid or unenforceable clause or provision as may be possible and be
legal, valid and enforceable.

      Section 21.9  Brokerage.  Landlord hereby warrants to Tenant that, except
for The Beal Companies ("Landlord's Broker"), no agent, broker or finder has
been retained by Landlord to represent Landlord in this transaction.  Tenant
hereby warrants to Landlord that, except for Lynch, Walsh & Partners ("Tenant's
Broker"), no agent, broker or finder has been retained by Tenant to represent
Tenant in this transaction.  Landlord shall be solely responsible for paying the
entirety of all commissions, fees, or compensation due to Landlord's Broker in
connection with this transaction. In addition, Landlord shall pay a fee to
Tenant's Broker in a total amount equal to the product of $4.00 multiplied by
the total number of square feet of Rentable Area in the Premises, which fee
shall be payable as follows and subject to the following conditions: (i) fifty
percent (50%) of such fee shall be payable upon the full execution and delivery
of the Lease; and (ii) fifty percent (50%) of such fee shall be payable upon the
Tenant's occupancy of any material portion of the Premises for the routine
conduct of its business and Landlord's receipt of the first installment of Base
Rent due hereunder.

      Section 21.10 Record Memorandum of Lease.  This lease will not be recorded
but a notice of lease in form reasonably satisfactory to both parties will be
recorded to be prepared by Tenant's attorney.  After the occurrence of the
Commencement Date, the parties will execute and acknowledge a recordable
memorandum setting forth a reference to this Lease, the parties' names, the
legal description of the Premises, the date on which the Commencement Date
occurred, the date on which the Expiration Date is scheduled to occur and a
short summary of Tenant's rights with respect to the Extension Term.

                  [remainder of page intentionally left blank]

                                       55
<PAGE>
 
     THIS LEASE AGREEMENT is executed and delivered as of the day and year first
above written as a sealed instrument.

TENANT:                             LANDLORD:

RENAISSANCE WORLDWIDE, INC.         WALTHAM 60/10 LLC



By:  /s/                            By: /s/ William K. Hoeg
   ------------------------------      ------------------------------
Its: Associate Counsel                 William K. Hoeg, its Chief Manager

                                    and

                                    By: /s/ Michael A. Manzo
                                       ------------------------------
                                       Michael A. Manzo, its Manager
<PAGE>
 
                                  EXHIBIT A-1

                           Legal Description of Site
                     on which Building is to be constructed


A certain parcel of land situated in the City of Waltham, Middlesex County,
Massachusetts bounded and described as follows:

Beginning at a point in the easterly line of Second Avenue, said point being
507.27 feet southerly along the easterly line of Second Avenue from its
intersection with the southwesterly line of Winter Street;

Thence turning and running S 78/degee/-31'-50" E, a distance of 219.33 feet to a
point;

Thence turning and running N 11/degree/-28'-10" E, a distance of 15.00 feet to a
point;

Thence turning and running S 78/degree/-31'-50" E, a distance of 51.00 feet 
to a point;

Thence turning and running N 11/degree/-28'-10" E, a distance of 7.00 feet to 
a point;

Thence turning and running S 78/degree/-31'-50" E, a distance of 28.00 feet 
to a point;

Thence turning and running S 11/degree/-28'-10" W, a distance of 7.00 feet to 
a point;

Thence turning and running S 78/degree/-31'-50" E, a distance of 30.87 feet 
to a point in the southwesterly line of State Highway Route 128, the previous
seven (7) courses by Phase I;

Thence turning and running S 32/degree/-32'-28" E, a distance of 130.81 feet 
to a point;

Thence turning and running S 02/degree/-14'-43" W, a distance of 116.65 feet 
to a point;

Thence turning and running by a curve to the right having a radius of 4,130.00
feet, a distance of 42.97 feet to a point, the previous three (3) courses being
along the southwesterly line of State Highway Route 128;

Thence turning and running by land now or formerly of Trustees of Real Estate
Investment Trust of America, N 78/degree/-31'-50" W, a distance of 440.05 feet
to a point in the easterly line of Second Avenue;

Thence turning and running along the easterly line of Second Avenue, N 
11/degree/-28'-10" W, a distance of 237.17 feet to the point of beginning.
<PAGE>
 
                                  EXHIBIT A-2

                    Legal Description of Ground Lease Parcel


                         40 SECOND AVENUE, WALTHAM, MA

A certain parcel of land situated in the City of Waltham, Middlesex County, 
Massachusetts, bounded and described as follows:

Beginning at a point in the easterly line of Second Avenue, said point being 
507.27 feet southerly along the easterly line of Second Avenue from its 
intersection with the southwesterly line of Winter Street;

Thence turning and running along the easterly line of Second Avenue, 
N 11/degrees/-28'-10" E, a distance of 121.49 feet to a point;

Thence turning and running northeasterly by a curve to the right having a 
radius of 25.00 feet, a distance of 39.27 feet to a point;

Thence turning and running S 78/degrees/-31'-50" E, a distance of 11.33 feet to
a point;

Thence turning and running by a curve to the right having a radius of 30.00 
feet, a distance of 27.40 feet to a point;

Thence turning and running by a curve to the left having a radius of 60.00 
feet, a distance of 181.67 feet to a point in the southwesterly line of State 
Highway Route 128, the previous four (4) courses being along the southerly line 
of Winter Place;

Thence turning and running southeasterly along the southwesterly line of State 
Highway Route 128 by a curve to the left having a radius of 312.00 feet, a 
distance of 70.05 feet to a point;

Thence turning and running along the southwesterly line of State Highway Route
128, S 32/degrees/-32'-28" E, a distance of 183.72 feet to a point;

Thence turning and running N 78/degrees/-31'-50" W, a distance of 30.87 feet to 
a point;

Thence turning and running N 11/degrees/-28'-10" S, a distance of 7.00 feet to a
point;

Thence turning and running N 78/degrees/-11'-50" W, a distance of 28.00 feet 
to a point;

Thence turning and running S 11/degrees/-28'-10" W, a distance of 7.00 feet to a
point;

Thence turning and running N 78/degrees/-31'-50" W, a distance of 51.00 feet 
to a point;

Thence turning and running S 11/degrees/-28'-10" W, a distance of 15.00 feet 
to a point;

Thence turning and running N 78/degrees/-11'-50" W, a distance of 219.33
feet to the point of beginning, the previous seven (7) courses by Phase IIA.
<PAGE>
 
                                   EXHIBIT B

             Preliminary Plans and Specifications for Base Building


The Base Building Plans contemplate the construction of the Base Building of
approximately 200,000 square feet of Rentable Area, as described in the
Schematic Plans and Outline Specifications contained in a letter from Landlord's
Representative, Peter B. Nichols, to Tenant's Representative, Duncan Andrews,
dated March 12, 1998, as described in the Floor Plate & Background Drawings,
Civil/Site Drawings, and the Base Building Design Documents provided by letter
from Peter B. Nichols to Duncan Andrews of April 24, 1998, and as further
recited below:

     1. Structural System:
        ----------------- 
          (a) A five level, reinforced concrete garage, one partial level below
          the level of Second Avenue.
          (b) Above the garage, will be a four story, structural steel moment
          frame office building with lightweight concrete floor system.
          (c) Standard office space live load design capacity is 80# psf.
          (d) Cafeteria and fitness areas will be 100# psf.

     2. Building Enclosure:
        ------------------ 
          (a) Exterior facade is a combination of Exterior Insulated Finish
          System ("EIFS") and red brick matching the 40 Second Avenue building.
          (b) Windows are double-glazed ("low E") window units with thermally
          broken, aluminum frames.
          (c) Roofing is an adhered sheet membrane system

     3. Code Compliance:
        ----------------
          (a) In full compliance with all applicable governmental rules,
          regulations and building codes, including but not limited to, ADA,
          MSBC.
          (b) Complying with Massachusetts Access Board requirements every
          toilet room on tenant floors will have disabled access facilities.
          (c) Exception: Private Executive Balconies will not be ADA accessible,
          as permitted by code.
          (d) Corridors will be constructed as necessary to demise the Premises
          in accordance with requirements under applicable codes for single
          tenant full floor occupancy.

     4. Elevators:
        ----------
          (a) Four geared-traction passenger elevators of 3,500 lb capacity, 400
          fpm, will serve parking garage levels P2, P3, P4, P5 and office levels
          1,2,3 &4.
          (b) Passenger cabs have bi-parting entrance doors, with a $20,000
          premium cab finish allowance over vendor standard ($5,000 per cab).
          (c) One geared-traction freight elevator, 4,500 lbs capacity, 150 fpm,
          serving parking garage level P2 and office levels 1,2,3 &4.

                                      B-1
<PAGE>
 
     5. HVAC System:
        ------------
          (a) Six rooftop heating & cooling air conditioning units serve the
          tenant spaces, vertically zoned, and one unit serves the atrium
          (common) area.  Each roof-top AC unit is sized to provide 
          /plus minus/25,000 cfm with /plus minus/75 tons cooling capacity. Any
          combination of the rooftop units can be operated during any 24 hour
          period to provide full service to tenant areas.
          (b) Packaged heat/air conditioning units have double-walled casings,
          return-air fans and exhaust boxes, filtered outside air intake
          sections, with remotely-controlled supply fans, vibration-control
          devices.  They have gas fired heating and electrically powered direct
          exchange cooling sections, with packaged condensing units.
          (c) Supply and return air distribution is made via proportionately
          sized medium pressure trunk lines located in vertical duct shaftways
          in the building core area, capped and available for Tenant connection,
          at the shaft walls at each floor.
          (d) Within the Premises and as part of the Leasehold Improvements,
          tempered air distribution is made on each floor to electrically
          powered VAV boxes via medium and low pressure ductwork, with requisite
          fire dampers, diffusers, return air grilles, and automatic temperature
          control systems.
          (e) Design Parameters (Per Energy Code):
               (i)    20 cfm per person at one person per 150 square feet
               (ii)   Summer: 75/degrees/F dry bulb at 88/degrees/F dry bulb/
                      74/degrees/F wet bulb outside
               (iii)  Winter: 70/degrees/F dry bulb at 0/degrees/F outside
          (f) All special requirements for supplemental cooling will be provided
          by Tenant via independent split systems installed at designated roof
          locations and distributed to specific floor locations by dedicated
          shaftways.
          (g) Overtime operation is at Tenant option by turning on any
          combination of rooftop units to serve necessary areas for 24 hour
          service.

     6. Electrical System:
        ------------------
          (a) Electric service is provided from main switchboard  located in P2
          level electrical room.  The 2,000 amp switchboard will serve the HVAC
          equipment and building common area loads, and a 4,000 amp switchboard
          will serve the Tenant's lighting and power requirements. Tenant can
          configure for check-metering based on the master meter.
          (b) Secondary (480 volt) electrical power distribution is via risers
          to each floor (electric closet) for Tenant connection and further
          distribution via 480 / 120 volt transformers, lighting & power panels.
          (c) Service to each floor's electric closet is sized to provide 6.5
          watts per square foot for Tenant lighting, supplemental AC units and
          other power requirements.  The main switchboard, on the 1st floor, is
          sized for an additional 2 watts per square foot.
          (d) The oil-fired, rooftop mounted, emergency generator for the base
          building systems is 550 KW capacity, using a 500 gallon storage tank
          located in the garage, designed for 10 hours of continuous operation,
          to serve life safety loads, including:

                                      B-2
<PAGE>
 
               (e)  Emergency Egress
               (f)  Exitways
               (g)  Fire Pump Operation
               (h)  Fire Alarm System
               (i)  One Elevator
               (j)  Stair Pressurization
               (k)  Atrium Smoke Exhaust
 
     7. Plumbing:
        ---------
          (a) Capped cold water, plugged sanitary and capped vent lines are
          located in core area vertical wet stacks for connection of Tenant-
          provided plumbing facilities
          (b)  Toilet / Washrooms:
               (i) To be located within the core area of each floor sized for 1
               person per 165 sq. Ft. (50% male / 50% female), equipped with
               handicapped-accessible water closet & lavatory facilities,
               ceiling-hung metal toilet partitions, soap and napkin dispensers.
               (ii) Ceramic Tile Floors and wet walls; other walls painted.
               (iii)  Moisture resistant acoustical tile ceilings (8'-4 Ht).
               (iv)  3'-0 x 8'-0 Solid Core, Oak Veneer Doors in knock-down 
               metal frames with push-pull hardware
               (v) Flourescent lighting & GFI electrical outlet
               (vi  Electric cabinet water heaters

     8. Fire Protection:
        --------------- 
          (a) Fire protection standpipes are located at each stairwell with  
          2 1/2" hose valves for fireman's connection.
          (b) Risers are extended, at each floor, to hydraulically-designed
          sprinkler  system at average density of one head per 225 square feet
          of rentable area.
          (c) Recessed, wall-mounted fire extinguisher cabinets are located at
          core area on each floor.

     9. Ceiling Systems:  (toilet rooms and related core areas)
        ----------------                                       
          (a) Acoustical ceilings: 24" x 24" x 5/8" fissured acoustical ceiling
          tile (similar to Acoustone Tegular Minatone) set in  15/16" exposed
          metal suspension system, white grid.

     10. Gypsum Wallboard System (GWB):
         ------------------------------
          (a) Ceiling-high ,5/8" gypsum wallboard on 2 1/2" metal stud system
          (exterior building walls and core walls to be 5/8" gypsum wallboard on
          1" furring), taped,  spackled and sanded, ready to receive Tenant's
          application of paint or wall covering materials. Toilet rooms and
          core-area mechanical equipment rooms and shaftways to be full height
          insulated partition walls (gypsum wallboard in toilet rooms to be
          moisture-resistant); elevator shafts to be 2" gypsum core-wall.

                                      B-3
<PAGE>
 
          (b)  Exterior Windows:
               ---------------- 
               (i) Paint-grade wood or Plastic Laminate window sills
               (ii  2 1/2" solid vinyl vertical louver drapes

     11. Floor Covering systems:
         ---------------------- 
          (a) In Tenant spaces, concrete floors are scraped, leveled, flash-
          patched, sealed, ready to accept Tenant floor covering materials.
          (b) In finished floor areas: (elevator lobbies and related core areas)
               (i) Carpet in a color, texture and pattern to be coordinated with
               Tenant interior design, based on an installed allowance of $24.00
               per square yard.
               (ii)  2 1/2" vinyl base (cove or straight) in all finished floor
               areas
          (c) Ceramic Tile to be installed in Toilet Rooms, based on an
          installed allowance of $ 7.50 / sf.
          (d) Atrium Floor will have 18" perimeter stone boundary with carpet
          infill. Allowances are $40 psf for stone and $3.50 psf for carpet.

     12. Elevator Lobbies:
         ---------------- 
          (a) Full-height gypsum wallboard partitions and core enclosures
          (b) 6'0 x 8'0 Solid Core Oak veneer double wood door, knock-down metal
          frames & lock set hardware systems at each office level.
          (c) Atrium Doors to exterior deck are narrow stile aluminum, hinged
          entry doors, factory painted finish with insulating tempered glass
          matching the building.
          (d) All paint will be polymix
          (e) Building Standard carpet and base
          (f) Millwork at elevator doors on 5% allowance
          (g) Ceilings and walls of GWB (standard)
          (h) Lighting and exit signage
          (i) Sprinkler heads
          (j)HVAC

     13. 3,000 sf  Cafeteria:
         ------------------- 
          (a) To be constructed by Landlord in accordance with Cafeteria Exhibit
          attached to this Exhibit B
          (b) HVAC exhaust will maintain area in negative pressure

     14. 2,000 sf  Fitness Center:  to be completed by Landlord in accordance
         ------------------------                                            
         with the Fitness Layout Plan dated __________, 1998, including:
          (a) Men's and Women's washroom facilities w/ fiberglass shower
          enclosures, and day lockers.
          (b) Exercise Room; building standard finishes, carpet, acoustical
          ceiling tile, painted gypsum wallboard.
          (c) HVAC exhaust will maintain area in negative pressure

     15. Data Communication & Telephone Systems:
         -------------------------------------- 
          (a) Telephone service is provided to street level building telephone
          room with empty vertical conduit to telephone closet in core area on
          each floor plus two empty vertical conduits from each telephone closet
          to roof antenna-placement area.
          (b) All data, communication, telephone and related system installation
          within building are by Tenant.

                                      B-4
<PAGE>
 
     16. Site Development:
         -----------------
          (a) Trash Compactor/Dumpster; 20 yard capacity

     17. Life Safety Systems:
         ------------------- 
          (a) ADA-compliant (visual and auditory) evacuation/fire alarm and
          instruction systems

     18. Emergency Exit Stairways:
         -------------------------
          (a) For office occupancy under all applicable terms and conditions of
          the MSBC.
          (b) Based on single-tenant, full-floor occupancy
          (c) Design occupancy classification: (S2) Parking, (B) Business
          (d) Concrete-filled, painted metal pan stairway systems with full-
          height GWB enclosing walls and self-closing, fire-rated exit doors on
          each floor, 3' 4" x 8' 0" at office levels,  3' 4" x 7' 0" at garage
          levels,  including:
               (i) Exitway signage and emergency lighting fixtures
               (ii)  Painted metal stairs and handrails
               (iii)  Painted interior enclosure walls

     19. Signage:
         --------
          (a) Allowance of $15,000 for exterior building sign and interior
          building directory.
          (b) Designed to mutual satisfaction of Tenant and Landlord.
          (c) In conformance with City of Waltham dimensional bylaws

     20. Security:
         ---------
          (a) Programmable Card Access to garage, exterior entry/exit doors,
          parking garage elevator lobbies, elevator cab operations to be
          designed in close coordination with Tenant's security consultant at a
          level of service consistent with systems typically found in first
          class office buildings on Route 128, including:
               (i) Access (security card) control system at 10 exterior building
               access doors to be specified.
               (ii)  Landlord will incur the cost of the system as part of the
               Base Building or, at Landlord's option, provide an allowance
               therefore in an amount not to exceed $30,000.

     21. Parking:
         --------
          (a) Parking for the building is provided at a ratio of 3.3 per
          thousand square feet of rentable square feet (not to exceed 660
          spaces) in a facility that is shared with occupants of 40 Second
          Avenue.  Landlord shall use reasonable efforts to segregate parking
          for 40 Second Avenue by installing informational or

                                      B-5
<PAGE>
 
          directional signage (but Landlord shall have no duty to construct or
          install separate entrances or barricades, or to police or enforce any
          restrictions in such signage).

                                      B-6
<PAGE>
 
                            WALTHAM CORPORATE CENTER
                            ------------------------

Floor Plate and Background Drawings:
     Plans A-106 through A-109;  4/23/98  (Before full height freight elevator)
     Freight Elevator Configuration Sketches: 4-23-98 (8 1/2" x 11")
Civil/Site Design Documents:
     Request for Determination of Applicability Set; Nov. 3, 1997, Rev. Nov.
     13, 1997, Plans C-100 through C-102 and C-200 through C-202.
     Civil/Site; Issued for Phase I Bids Set; Dec. 29, 1997, Rev. Apr. 13, 1998
     Plans C-100 through C-104

                    Detailed Base Building Design Documents
                    ---------------------------------------

                 GMP Bid Set: 4-22-98 (unless otherwise noted)
                 ---------------------------------------------


COVER     DRAWING LIST, CODE ANALYSIS, ABBREVIATIONS, NOTES (A-000)
 
SITE
----- 
C-100   SITE PREPARATION PLAN; Dec. 29, 1997, Rev. 4-13-98
C-101   UNDERGROUND UTILITIES PLAN, April 13, 1998
C-102   GRADING & DRAINAGE PLAN, April 13, 1998
C-103   SITE UTILITIES DETAILS, April 13, 1998
C-104   SITE PREP. DETAILS, April 13, 1998
        TOPOGRAPHIC PLAN, Nov. 21, 1997
 
ARCHITECTURAL
------------- 
    AD-101         LEVEL P-2 DEMOLITION PLAN
    A-101          LEVEL P-1 PARKING PLAN
    A-102          LEVEL P-2 PARKING PLAN
    A-103          LEVEL P-3 PARKING PLAN
    A-104          LEVEL P-4 PARKING PLAN
    A-105          LEVEL P-5 PLAN
    A-106          LEVEL L-1 OFFICE PLAN
    A-107          LEVEL L-2 OFFICE PLAN
    A-108          LEVEL L-3 OFFICE PLAN
    A-109          LEVEL L-4 OFFICE PLAN
    A-110          ROOF PLAN
    A-121          REFLECTED CEILING PLAN/LEVEL P-1
    A-122          REFLECTED CEILING PLAN/LEVEL P-2
    A-123          REFLECTED CEILING PLAN/LEVEL P-3
    A-124          REFLECTED CEILING PLAN/LEVEL P-4
    A-125          REFLECTED CEILING PLAN/LEVEL P-5
    A-200          EXTERIOR ELEVATIONS
    A-201          EXTERIOR ELEVATIONS
    A-202          EXTERIOR ELEVATIONS
    A-203          EXTERIOR ELEVATIONS

                                      B-7
<PAGE>
 
    A-300          WALL SECTIONS
    A-301          WALL SECTIONS
    A-400          ENLARGED CORE PLANS
    A-401          ENLARGED CORE PLANS
    A-402          ENLARGED CORE PLANS
    A-403          ENLARGED CORE PLANS
    A-404          ENLARGED CORE PLANS
    A-405          EAST FACADE PLANS
    A-406          ENLARGED ATRIUM PLAN
    A-441          STAIR PLANS
    A-442          STAIR PLAN
    A-444          STAIR SECTION/PLAN
    A-445          STAIR PLANS
    A-446          STAIR SECTION/PLAN
    A-500          EXTERIOR DETAILS
    A-501          EXTERIOR DETAILS
    A-502          EXTERIOR DETAILS
    A-503          EXTERIOR DETAILS
    A-504          EXTERIOR DETAILS
    A-505          EXTERIOR DETAILS
    A-600          DOOR ELEVATIONS & DETAILS
    A-700          WINDOW TYPES & DETAILS
    A-900          INTERIOR DETAILS

STRUCTURAL: (April 16, 1998 Set)
--------------------------------
    S-001          GENERAL NOTES AND TYPICAL DETAILS
    S-002          TYPICAL DETAILS
    S-003          TYPICAL DETAILS
    S-101          LEVEL P-1 PARKING PLAN
    S-102          LEVEL P-2 PARKING PLAN
    S-103          LEVEL P-3 PARKING PLAN
    S-104          LEVEL P-4 PARKING PLAN
    S-105          LEVEL P-5 PARKING/OFFICE PLAN
    S-106          LEVEL 2 OFFICE PLAN
    S-107          LEVEL 3 OFFICE PLAN
    S-108          LEVEL 4 OFFICE PLAN
    S-109          LEVEL 5 OFFICE PLAN
    S-110          ROOF PLAN
    S-201          BEAM, FOOTING, WALL REINFORCING SCHEDULE & DETAILS
    S-202          SLAB DETAILS
    S-301          COLUMN SCHEDULE
    S-302          COLUMN SCHEDULE
    S-303          COLUMN SCHEDULE AND DETAILS
    S-401          SECTIONS
    S-402          SECTIONS


                                      B-8
<PAGE>
 
HVAC
---- 
    M-1            HVAC SCHEDULE SHEET #1
    M-2            HVAC SCHEDULE SHEET #2
    M-3            HVAC FLOOR PLAN PARKING LEVEL P-1
    M-4            HVAC FLOOR PLAN PARKING LEVEL P-2
    M-5            HVAC FLOOR PLAN PARKING LEVEL P-3
    M-6            HVAC FLOOR PLAN PARKING LEVEL P-4
    M-7            HVAC FLOOR PLAN PARKING P-5
    M-8            HVAC FLOOR PLAN OFFICE L-1
    M-9            HVAC FLOOR PLAN OFFICE L-2
    M-10           HVAC FLOOR PLAN OFFICE L-3
    M-11           HVAC FLOOR PLAN OFFICE L-4
    M-12           HVAC ROOF/PENTHOUSE PLAN
    M-13           HVAC AIR RISER DIAGRAM SHEET #1
    M-14           HVAC AIR RISER DIAGRAM SHEET #2
    M-15           HVAC DETAIL SHEET #1
    M-16           HVAC DETAIL SHEET #2
 
ELECTRICAL
---------- 
    E-1            SYMBOL LIST
    E-2            LEVEL P-1 PARKING POWER & LIGHTING PLAN
    E-3            LEVEL P-2 PARKING POWER & LIGHTING PLAN
    E-4            LEVEL P-3 PARKING POWER & LIGHTING PLAN
    E-5            LEVEL P-4 PARKING POWER & LIGHTING PLAN
    E-6            LEVEL P-5 PARKING POWER & LIGHTING PLAN
    E-7            LEVEL 1 OFFICE PLAN
    E-8            LEVEL 2 OFFICE PLAN
    E-9            LEVEL 3 OFFICE PLAN
    E-10           LEVEL 4 OFFICE PLAN
    E-11           ROOF PLAN
    E-12           DETAILS SHEET #1
    E-13           DETAILS SHEET #2
    E-14           PANELBOARDS SCHEDULES
    E-15           LIGHTING FIXTURE LIST
    E-21           ELECTRICAL RISER DIAGRAM
    E-22           ENLARGED PARTIAL PLANS
 
PLUMBING
-------- 
    P-1            PLUMBING PARKING PLAN P-1
    P-2            PLUMBING PARKING PLAN P-2
    P-3            PLUMBING PARKING PLAN P-3
    P-4            PLUMBING PARKING PLAN P-4
    P-5            PLUMBING FLOOR PLAN LEVEL P-5
    P-6            PLUMBING FLOOR PLAN OFFICE LEVEL 1
    P-7            PLUMBING FLOOR PLAN OFFICE LEVEL 2

                                      B-9
<PAGE>
 
    P-8            PLUMBING FLOOR PLAN OFFICE LEVEL 3
    P-9            PLUMBING FLOOR PLAN OFFICE LEVEL 4
    P-10           PLUMBING ROOF PLAN
    P-11           PLUMBING LEGEND, SCHEDULE & DETAILS
    P-13           PLUMBING SANITARY RISER DIAGRAM
    P-14           PLUMBING WATER RISER DIAGRAM
    P-15           PLUMBING RWL RISER DIAGRAM

FIRE PROTECTION
---------------
    SP-1           LEVEL P-1 PARKING SPRINKLER PLAN
    SP-2           LEVEL P-2 PARKING SPRINKLER PLAN
    SP-3           LEVEL P-3 PARKING SPRINKLER PLAN
    SP-4           LEVEL P-4 PARKING SPRINKLER PLAN
    SP-5           LEVEL P-5 OFFICE SPRINKLER PLAN
    SP-6           LEVEL 1 OFFICE SPRINKLER PLAN
    SP-7           LEVEL 2 OFFICE SPRINKLER PLAN
    SP-8           LEVEL 3 OFFICE SPRINKLER PLAN
    SP-9           LEVEL 4 OFFICE SPRINKLER PLAN
    SP-10          ROOF SPRINKLER PLAN
    SP-11          RISER SCHEDULES, DETAILS

                                     B-10
<PAGE>
 
                               CAFETERIA EXHIBIT

FOOD PREPARATION CAPABILITIES

A.   A 1,200 square foot kitchen and servery utilizing disposable plates and
     utensils, sufficient for the following types of food to be served:

     .    Hot dogs
     .    Hamburgers (char grilled)
     .    French fries
     .    Salads
     .    Sandwiches (with a deli case)
     .    Two (2) hot entree with a four bay serving line
     .    Desserts with a refrigerated section
     .    Beverages (hot and cold)
     .    Soup with two tureens

B.   Tables to be 36" x 36" plastic laminate top with wood edge.  On metal "X"
     base.  Mfg -Howe or equal

C.   Chairs to be stacking, armless, bentwood or upholstered seat with sled
     base.  Mfg - Thonet or equal.

D.   Kitchen to be equipped as per attached 6/25/98 equipment list of Aram J.
     Pothier Group, Incorporated or equivalent.

                                     B-11
<PAGE>
 
                                   EXHIBIT C

                                  Work Letter


     This Work Letter is attached to and made are part of a Lease Agreement
dated as of June 30, 1998 (the "Lease"), by and between WALTHAM 60/10 LLC
("Landlord") and RENAISSANCE WORLDWIDE, INC. ("Tenant").

     1. Definitions.  All capitalized terms used in this Work Letter without
        -----------                                                         
     definition will have the meanings set forth for such terms in the Lease.

     2. Completion Schedule.  Attached hereto as Schedule No. 1 is a schedule
        -------------------                                                  
     (the "Work Schedule") setting forth a timetable for the planning and
     completion of the installation of the Leasehold Improvements to be
     constructed in the Premises and the targeted Commencement Date for the Term
     of the Lease.  The Work Schedule is intended to set forth each of the
     various items of work to be done by or approval to be given by Landlord and
     Tenant in connection with the completion of the Leasehold Improvements.
     Such Work Schedule will be the basis for completing the Tenant Improvement
     work.

     3. Leasehold Improvements.  The term "Leasehold Improvements" means all
        ----------------------                                              
     leasehold improvements, installations and other work, with the exception of
     the Base Building, to be completed in the Premises by Landlord for Tenant
     pursuant to the Leasehold Improvements Plans described in paragraph 5
     below, including, but not limited to, partitioning, doors, ceilings, floor
     coverings, wall finishes, electrical (including lighting, switching,
     outlets, etc.), plumbing, heating, ventilating and air conditioning and
     fire protection.

     4. Program Information; Leasehold Improvements Design Documents.  Landlord
        ------------------------------------------------------------           
     has delivered to Tenant the Preliminary Plans, Floor Plate and Background
     Drawings, the Civil/Site Design Documents, the Detailed Base Building
     Design Documents, the Base Building Cafeteria, Fitness and Patio Layout
     Plan, the Base Building Construction Documents and the other documents for
     the Base Building described on Exhibit B attached to the Lease, for use by
                                    ---------                                  
     Tenant in preparation of the design development documents for the Leasehold
     Improvements, which will consist of a space layout, and final and complete
     plans, details and other documents which fix dimensions and describe the
     size and character of the Leasehold Improvements to be constructed in the
     Premises, including all architectural, structural, mechanical and
     electrical systems, materials and such other elements as may be appropriate
     to enable Landlord to prepare the Leasehold Improvement Plans and are
     sufficient to obtain preliminary pricing from subcontractors (the
     "Leasehold Improvements Design Documents").  Tenant will cause the
     Leasehold Improvements architect to prepare and deliver the Leasehold
     Improvements Design Documents consistent with the Preliminary Plans and the
     Base Building Plans  to Landlord on or before August 14, 1998, for
     Landlord's review and approval.  Each day after August 14, 1998 and to 

                                      C-1
<PAGE>
 
     and including September 13, 1998 that Tenant has not delivered the
     Leasehold Improvements Design Documents to Landlord will be a day of
     Permitted Delay, but not a day of Tenant Delay. Each day after September
     13, 1998 and until Tenant has delivered the Leasehold Improvements Design
     Documents to Landlord will be a day of Tenant's Delay. Within fifteen
     business days after receipt of the proposed Leasehold Improvements Design
     Documents, Landlord will either approve the same in writing or notify
     Tenant in writing of how the proposed Leasehold Improvements Design
     Documents is inconsistent with the Base Building Plans or the Preliminary
     Plans and how the Leasehold Improvements Design Documents must be changed
     in order to make it consistent with the Base Building Plans and the
     Preliminary Plans. Each day following the 15/th/ business day after the
     proposed Leasehold Improvements Design Documents is submitted to Landlord
     until Landlord approves it or delivers such notice of objections will be a
     day of Landlord's delay. Within fifteen business days after receipt of
     Landlord's notice of objections, Tenant will cause the Leasehold
     Improvements architect to prepare a revised Leasehold Improvements Design
     Documents according to such notice and submit the revised Leasehold
     Improvements Design Documents to Landlord . Each day after such date until
     Tenant has delivered the revised Leasehold Improvements Design Documents to
     Landlord will be a day of Tenant's Delay. Upon submittal to Landlord of the
     revised Leasehold Improvements Design Documents, and upon submittal of any
     further revisions, the procedures described above will be repeated until
     the Leasehold Improvements Design Documents is approved by Landlord.

     5. Leasehold Improvements Plans.  Within 60 days after the Leasehold
        ----------------------------                                     
     Improvements Design Documents have been approved by Landlord, Tenant will
     cause the Leasehold Improvements architect to prepare construction plans
     and specifications for the Leasehold Improvements based on the approved
     Leasehold Improvements Design Documents (the "Leasehold Improvements
     Plans") and submit same to Landlord for review and approval pursuant to
     this paragraph.  Within five business days after receipt of the proposed
     Leasehold Improvements Plans, Landlord will either approve the same in
     writing or notify Tenant in writing of how the proposed Leasehold
     Improvements Plans are inconsistent with the Leasehold Improvements Design
     Documents and how the Leasehold Improvements Plans must be changed in order
     to make them consistent with the Leasehold Improvements Design Documents.
     If Landlord fails to approve or deliver its objections to the proposed
     Leasehold Improvements Plans within five business days after delivery by
     Tenant, Landlord will be deemed to have approved the Tenant Improvements
     Plans.  After receipt of Landlord's notice of objections, Tenant will cause
     the Leasehold Improvements architect to prepare revised Leasehold
     Improvements Plans according to such notice and submit the revised
     Leasehold Improvements Plans to Landlord.  Upon submittal to Landlord of
     the revised Leasehold Improvements Plans and upon submittal of any further
     revisions, the procedures described above will be repeated until the
     Leasehold Improvements Plans are approved by Landlord.  After final
     approval (or deemed approval) by Landlord and Tenant, all further changes
     to the Leasehold Improvements Plans may be made in accordance with Section
     3.8 of the Lease. Tenant will not be charged any fee by Landlord for
     Landlord's review of the

                                      C-2
<PAGE>
 
     Leasehold Improvements Design Documents or the Leasehold Improvements (it
     being acknowledged that the fees of the Leasehold Improvements architect
     shall be included as part of Tenant's Cost).

     6. Tenant's Cost Proposal.  Within 15 business days after the approval of
        ----------------------                                                
     the Leasehold Improvements Plans by both Landlord and Tenant, Landlord will
     provide to Tenant the names of experienced, qualified and reputable
     subcontractors and suppliers to whom Landlord or Landlord's general
     contractor will submit requests for bids to perform all or a portion of the
     Leasehold Improvements, as subcontractors to ADP Marshall Inc.  Tenant
     shall submit a list of any additional experienced, qualified and reputable
     subcontractors and suppliers who are union contractors and to whom Tenant
     wants bid packages sent.  If Tenant fails to deliver such list of
     subcontractors or suppliers within the fifth business day after delivery of
     Landlord's list of proposed contractors and subcontractors, Tenant shall be
     deemed to have approved Landlord's list.  Within thirty days after receipt
     by Landlord of Tenant's list of additional subcontractors, Landlord will
     obtain bids for the Leasehold Improvements and Landlord, Tenant and
     Landlord's general contractor shall meet together to review all bids
     submitted and to select the best reasonable price for the Leasehold
     Improvements.  On the basis of such review, within 10 days after the review
     by Landlord and Tenant of the bids, Landlord shall (i) prepare a proposed
     budget for all items to be included in Tenant's Cost ("Tenant's Cost
     Proposal"); and (ii) submit a written breakdown of all bids selected and
     Tenant's Cost Proposal to Tenant for Tenant's review and approval.  Tenant,
     at Tenant's option, may either approve Tenant's Cost proposal in writing or
     elect to eliminate or revise one or more items of Leasehold Improvements
     shown on the Leasehold Improvements Plans and then approve in writing the
     modified Tenant's Cost Proposal (based on the revised Leasehold
     Improvements Plans).  Tenant's modifications may include, without
     limitation, the selection of another subcontractor (one of the bidders).
     If Tenant fails to approve or deliver its objection to the Tenant's Cost
     Proposal within the 5/th/ business day after delivery by Landlord, Tenant
     shall be deemed to have approved Tenant's Cost Proposal.

     7. Construction of Leasehold Improvements.  After the Leasehold
        --------------------------------------                      
     Improvements Plans have been prepared and approved and Tenant has approved
     Tenant's Cost Proposal, Landlord will engage the general contractor to
     obtain all applicable building permits and cause the Leasehold Improvements
     to be constructed or installed in the Base Building in a good and
     workmanlike manner and according to the Leasehold Improvements Plans and
     all applicable Laws.  Landlord will require that such contractor use
     commercially reasonable efforts to secure substantial completion of the
     work in accordance with Work Schedule.  The cost of such work will be paid
     as provided in Paragraph 8 hereof.

     8. Payment of Cost of the Leasehold Improvements.
        --------------------------------------------- 

          (a) Landlord hereby grants to Tenant an allowance (the "Leasehold
          Improvements Allowance") of $29.00 per square foot of Rentable Area of
          the Premises, or, subject to adjustment pursuant to Section 3.10 of
          the Lease, a total of $5,800,000.  Such Leasehold Improvements
          Allowance may be used for items including but not limited to the
          following:

                                      C-3
<PAGE>
 
               (i)   Payment of the cost of preparing the Leasehold Improvements
                     Design Documents and the Leasehold Improvements Plans.

               (ii)  The payment of plan check, permit, inspection and license
                     fees and cost relating to construction of the Leasehold 
                     Improvements.

               (iii) Construction of the Leasehold Improvements in their
                     entirety, including, without limitation, the following:

                    (1) Installation within the Premises of all partitioning,
                    doors, floor coverings, ceilings, wall coverings and
                    painting, mill-work and similar items.

                    (2) All electrical wiring, lighting fixtures, outlet
                    switches, and other electrical work to be installed within
                    the Premises.

                    (3) The furnishing and installation of all duct work,
                    terminal boxes, diffusers and accessories required for the
                    completion of the heating, ventilation and air condition
                    systems within the Premises.

                    (4) Any additional Tenant requirements including, but not
                    limited to odor control, special heating, ventilation and
                    air conditioning, noise or other special systems.

                    (5) All plumbing, fixtures, pipes and accessories to be
                    installed within the Premises.

                    (6)  Testing and inspection costs.

          Except as otherwise set forth in this Work Letter, the Leasehold
          Improvements Allowance will be disbursed by Landlord and applied as
          payment toward the installation of all Leasehold Improvements and
          costs of planning, design and miscellaneous fees associated therewith.

          (b) Tenant will be responsible for payment of the amount, if any, by
          which Tenant's Cost exceeds the Leasehold Improvements Allowance
          ("Tenant's Excess Cost") which amount shall be applied to the
          Leasehold Improvements cost before payment of any portion of the
          Leasehold Improvements Allowance.  Tenant will pay the amount of
          Tenant's Excess Cost to Landlord in monthly progress payments due
          within five business days after receipt by Tenant of Landlord's
          invoice therefor, accompanied by reasonable backup 

                                      C-4
<PAGE>
 
          such as copies of an itemized draw request from Landlord's general
          contractor and a statement of Tenant's architect or other evidence
          reasonably satisfactory to Tenant that the work reflected on the
          submitted invoices has been completed and the materials reflected on
          the submitted invoices have been delivered to the Premises. Each
          payment by Tenant will be in the amount of Landlord's invoice, less
          the retainage, if any, in the Landlord's contract with the general
          contractor with respect to such work. Final payment of such retainage
          will be due within 30 days after the occurrence of the Commencement
          Date. Upon the payment or retainage by Tenant of the entirety of the
          Tenant's Excess Cost in accordance with the foregoing provisions of
          this subparagraph, Landlord shall thereafter apply the Landlord
          Improvements Allowance to Tenant's Costs as the same become due.

          (c) In the event that after the Leasehold Improvements Plans have been
          prepared and Tenant's Cost Proposal has been approved by Tenant,
          Tenant requires any change, addition or alteration in the approved
          Leasehold Improvements Plans, Tenant will prepare plans and
          specifications with respect to such change, addition or alteration and
          submit the plans to Landlord for approval. Within ten business days
          after the submission of the plans and specifications, Landlord will
          prepare and deliver to Tenant a Change Order in accordance with the
          provisions of Section 3.8 of the Lease.

          (d) In the event that the cost of the Leasehold Improvements increases
          over that set forth in Tenant's Cost Proposal due to the requirements
          of any governmental agency, Tenant will pay Landlord the amount of any
          such increase in the manner set forth in Paragraph 8(b) above.

          (e) Any unused portion of the Leasehold Improvements Allowance will
          not be paid in cash to Tenant or by a credit against Rent, but shall
          remain available to Tenant, without interest, to reimburse Tenant for
          the cost of Alterations to the Premises during the Term.

          (f) Landlord will bear the following costs relating to the Leasehold
          Improvements and the Base Building work and none other, except as
          provided herein

               (i)   Design and construction of the Base Building.

               (ii)  Costs associated with the use of the freight elevator 
                     during construction of the Leasehold Improvements and 
                     subsequent move-in.

               (iii) Premiums or other incremental portion thereof for insurance
                     policies procured by Landlord and applicable to periods 
                     of time prior to the Commencement Date.

                                      C-5
<PAGE>
 
               (iv)  Costs associated with bonding of any subcontractors and/or
                     vendors if imposed by Landlord or its agents.

               (v)   Electric consumption during construction of the Leasehold
                     Improvements.

     9.   Accounting Records.
          ------------------ 

          (a) Landlord will keep full and detailed accounts and will exercise
          such controls as may be necessary for the proper financial management
          of the Leasehold Improvements.  Landlord's accounting and control
          systems will be satisfactory to the Tenant.  Tenant and Tenant's
          Representative will be afforded access to Landlord's records, books,
          correspondence, instructions, drawings, receipts, invoices, agreements
          vouchers and other data relating to the Leasehold Improvements for the
          purpose of reviewing, auditing and/or copying such material when
          reasonably requested by Tenant.

          (b) Landlord will require the selected general contractor to, not less
          than on a monthly basis, deliver to the Tenant a statement showing in
          complete detail (itemized by contractor, subcontractor, vendor,
          consultants, etc.) all monies paid out or costs incurred by the
          Landlord in connection with the Leasehold Improvements, as well as all
          executed Change Orders, during the period commencing on the first day
          of each month preceding the current month and ending on the last day
          of said proceeding month, together with such supporting documentation
          as may be reasonably required by Tenant.

     10. Substantial Completion and Rent Commencement Date.  The commencement of
         -------------------------------------------------                      
     the Term of the Lease and Tenant's obligation for the payment of Rent under
     the Lease will commence as provided in the Lease.

                                      C-6
<PAGE>
 
                                 Schedule No. 1



                                 Work Schedule
                                 -------------
 
 
        Responsible Party  Abbreviations:
        -----------------  ----------------------
        "T" = Tenant       "TI" Leasehold Improvements
        "LL" = Landlord    "BB" Base Building

<TABLE> 
<CAPTION> 
Plan Description                        Responsible   Date Due          Status
                                        Party
<S>                                     <C>          <C>               <C>
Floor Plate and Background              LL            4/24/98          Issued and
 Drawings to T                                                         approved
                                                                       by Tenant
Civil/Site Design Documents to          LL            4/24/98          Issued and
 Tenant                                                                approved
                                                                       by Tenant
Detailed BB Design Documents to         LL            4/24/98          Issued and
 Tenant                                                                approved
                                                                       by Tenant
BB Cafeteria, Fitness and Patio         LL            5/22/98          Issued and
 layout plan to T                                                      approved
                                                                       by Tenant
Complete BB Construction                LL            6/22/98          Issued by
 Documents                                                             Landlord;
                                                                       not approved by
                                                                       Tenant

BB Materials Presentation to T          LL            7/15/98

Leasehold Improvements Design           T             8/14/98
 Documents to LL

BB Interior Finishes Presentation to    LL            8/15/98
 T

Leasehold Improvement Plans to LL       T             60 days after
                                                      approval by
                                                      LL of
                                                      Leasehold
                                                      Improvement
                                                      Design
                                                      Documents
</TABLE> 
<PAGE>
 
<TABLE> 
<CAPTION> 
Plan Description                        Responsible   Date Due          Status
                                        Party
<S>                                     <C>          <C>               <C>
Subcontractor List to T                 LL           15 business
                                                     days after
                                                     approval by
                                                     LL of
                                                     Leasehold
                                                     Improvement
                                                     Plans

Receipt of bids by LL for Leasehold     LL           30 days after
 Improvements and Meeting with T                     delivery by T
 and GC                                              of additional
                                                     subcontractors,
                                                     if any

Tenant's Cost Proposal to T             LL           10 days after
                                                     review by LL
                                                     and T of bids

Commence Tenant Improvement             LL           30 days after
 Construction                                        acceptance of
                                                     bids by LL

Punchlist Completed                     LL           6/18/99

Projected Lease Commencement            LL           6/30/99
 Date
</TABLE>
<PAGE>
 
                                   EXHIBIT D
                                   ---------

                             JANITORIAL STANDARDS
                             --------------------


GENERAL CLEANING SERVICES
-------------------------

NIGHTLY OFFICES (Monday through Friday, inclusive, Holidays excepted)
---------------

1.   Empty and damp clean ashtrays
2.   Empty waste baskets and remove trash (with the exception of those waste
     receptacles and containers used for medical waste, which shall be emptied
     and the trash disposed of by Tenant)
3.   Vacuum all carpeting
4.   Spot clean doors, walls and light switches, entrance door and glass


WEEKLY OFFICES
--------------

1.   Dust and wipe clean all office furniture, woodwork and basewalls
2.   Vacuum all carpet edges


MONTHLY OFFICES
---------------

1.   Dust all window blinds
2.   Dust tops of all files
3.   Dust all ceiling diffusers


NIGHTLY LAVATORIES
------------------

1.   Wash toilet seats, bowls, urinals and basins with approved germicidal 
     detergent
2.   Sweep and wash floor with approved germicidal detergent
3.   Clean all mirrors, shelves and bright work etc. including flushometer
     and receptacles
4.   Spot clean doors, partitions and wall
5.   Dust window sills
6.   Remove wastepapers
7.   Refill tissue holders, soap dispensers and towel dispensers

                                      D-1
<PAGE>
 
*SUPPLIES TO BE FURNISHED BY OWNER


MONTHLY LAVATORIES
------------------

1.   Wash all partitions and walls
2.   Clean all exhaust fan grills


QUARTERLY LAVATORIES
--------------------

1.   Machine scrub all flooring


NIGHTLY STAIRWELL AND CORRIDORS
-------------------------------

1.   Vacuum all carpeting
2.   Sweep and damp mop all flooring
3.   Dust all railings, edges and window sills
4.   Empty and clean all ashtrays
5.   Spot wash all walls
6.   Wash basement stairs and corridor


WEEKLY STAIRWELL AND CORRIDORS
------------------------------

1.   Wash all stairs
2.   Corner vacuum all carpeting


NIGHTLY LOBBY
-------------

1.   Vacuum all carpet
2.   Vacuum at all entrance doors
3.   Wet mop rear entrance lobby floor
4.   Empty and clean ashtrays
5.   Spot clean walls and base
6.   Clean all entrance glass and doors
7.   Sweep all entrance steps

                                     D-2
<PAGE>
 
WEEKLY LOBBY
------------

1.   Dust directory and plaques


NIGHTLY ELEVATORS
-----------------

1.   Vacuum carpets
2.   Clean walls
3.   Clean stainless steel in and outside of elevators with approved cleaner
4.   Remove trash from ceiling grill


WEEKLY ELEVATORS
----------------

1.   Vacuum all elevator tracks
2.   Dust ceiling fans


MONTHLY ELEVATORS
-----------------

1.   Dust ceiling grills


NIGHTLY LAB AREA
----------------

1.   Sweep
2.   Damp mop
3.   Empty trash


SNOW REMOVAL
------------

1.   After a 2" or greater snowfall, the snow will be removed from walkways,
     driveways, parking areas and steps.
2.   In cases of ice storms or other icy conditions, sand or other de-icing
     material shall be applied as necessary to walkways, driveways, parking
     areas and steps.

                                      D-3
<PAGE>
 
                                   EXHIBIT E

                             Existing Encumbrances



1.   Real estate taxes and municipal charges not yet due and payable.

2.   Drainage Easement twenty feet wide extending from the Southwesterly corner
     of the premises in a southerly direction created in a Deed duly recorded
     with the Middlesex Southern District Registry of Deeds (the "Registry") in
     Book 12387, Page 314.

3.   Notification of Non-Significance filed by Waltham Conservation Commission
     on September 24, 1992 with the Registry in Book 22426, Page 137.

4.   The following matters disclosed by that certain Plan entitled "ALTA/ASCM
     Land Title Survey Plan of Land in Waltham, Mass. (Middlesex County)
     Prepared For: The Beal Companies" dated August 29, 1997:

     (a) rip-rap swale encroaches over southeasterly boundary
     (b) concrete and bituminous walks along Second Avenue encroach onto
         premises
     (c) guy wire encroaches

5.   Order by the Land Court (Misc. Case No. 128509) for the issuance of a
     Special Permit as set forth in an instrument recorded with the Registry in
     Book 20433, Page 311, as affected by Orders by City of Waltham City Council
     recorded with the Registry in Book 24557, page 61 and Book 25336, Page 119.

6.   Superseding Order of Conditions filed by Commonwealth of Massachusetts on
     November 13, 1992 with the Registry in Book 22613, Page 209, as affected by
     Certificate of Compliance recorded with the Registry in Book 23709 Page
     251.

7.   Planning Board Covenants as set forth in an instrument recorded with the
     Registry in Book 20390, Page 154, as affected by Covenant Release to Lots
     A, B and C on plan recorded with the Registry in Book 20390, Page 153 and
     Release recorded with the Registry in Book 22408, Page 397.
<PAGE>
 
                                   Exhibit F

                             Sublease Requirements


     The terms of the Sublease with Massachusetts General Physicians
Organization, Inc. ("MGP"), as provided in Section 9.2, are as follows:


Sublandlord:        Renaissance Worldwide, Inc.

Subtenant:          MGP

Area:               3,500 square feet on the first floor

Rent:               Base rent of $22.00 per square foot of Rentable Area, plus
                    subtenant's proportionate share of Operating Costs

Tenant Improvement
Allowance:          $23.00 to be paid by Sublandlord

Term:               Term ending ______________, 2005

Extension Option:   Two five year extension options (but not to exceed the
                    Term of the Lease) at base rent equal to 95% of the then 
                    fair market rent for the Premises.