<PAGE>

                                                                Exhibit 10.4

                                    CONTENTS

1.   REFERENCE DATA                                                           1
     1.1      Exhibits                                                        1
     1.2      Definition References                                           1

2.   DESCRIPTION OF PREMISES                                                  1
     2.1      Demised Premises                                                1
     2.2      Park                                                            1
     2.3      Appurtenant Rights                                              1
     2.4      Exclusions and Reservations                                     1

3.   TERM OF LEASE                                                            2
     3.1      Definitions                                                     2
     3.2      Habendum                                                        2
     3.3      Declaration Fixing Term Commencement Date                       2

4.   READINESS FOR OCCUPANCY - ENTRY BY TENANT
     PRIOR TO TERM COMMENCEMENT DATE                                          3
     4.1      Completion Date - Delays                                        3
     4.2      When Landlord's Work Deemed Substantially Complete              3
     4.3      Plans and Specifications                                        4
     4.4      Preparation of Premises                                         5
     4.5      Cost of Materials                                               5
     4.6      Tenant's Delay - Additional Costs                               5
     4.7      Entry by Tenant Prior to Term Commencement Date                 6
     4.8      Conclusiveness of Landlord's Performance                        6
     4.9      Tenant Payments of Construction Cost                            6

5.   USE OF PREMISES                                                          7
     5.1      Permitted Use                                                   7
     5.2      Prohibited Uses                                                 7
     5.3      Licenses and Permits                                            7
     5.4      Vacancy by Tenant                                               7

6.   RENT                                                                     8
     6.1      In General                                                      8
     6.2      Commencement of Rent                                            8
     6.3      Rentable Area                                                   8

7.   HAZARDOUS MATERIALS                                                      9

8.   SERVICES FURNISHED BY LANDLORD                                           11
     8.1      Electric Current                                                11
     8.2      Water                                                           13
     8.3      Heat and Cleaning                                               13
<PAGE>


     8.4      Air Conditioning                                                14
     8.5      Additional Heat, Cleaning and \Air Conditioning Services        14
     8.6      Additional Air Conditioning Equipment                           14
     8.7      Repairs                                                         15
     8.8      Interruption or Curtailment of Services                         15
     8.9      Energy Conservation                                             16
     8.10     Miscellaneous                                                   16
     8.11     Park Security                                                   16

9.   ESCALATION                                                               17
     9.1      Definitions                                                     17
     9.2      Tax Excess                                                      21
     9.3      Operating Expense Excess                                        22
     9.4      Part Years                                                      22
     9.5      Effect of Taking                                                23
     9.6      Adjustment of Operating Costs and Taxes based upon Occupancy    23
     9.7      Survival of Obligations                                         23

10.  CHANGES OR ALTERATIONS BY LANDLORD                                       24

11.  FIXTURES, EQUIPMENT AND IMPROVEMENTS - REMOVAL BY TENANT                 25

12.  ALTERATIONS AND IMPROVEMENTS BY TENANT                                   25

13.  TENANT'S CONTRACTORS - MECHANIC'S AND OTHER LIENS -
     STANDARD OF TENANT'S PERFORMANCE - COMPLIANCE WITH
     LAWS                                                                     26

14.  REPAIRS BY TENANT - FLOOR LOAD                                           27
     14.1     Repairs by Tenant                                               27
     14.2     Floor Load - Heavy Machinery                                    28

15.  INSURANCE, INDEMNIFICATION, EXONERATION AND
     EXCULPATION                                                              28
     15.1     General Liability Insurance                                     28
     15.2     Certificates of Insurance                                       28
     15.3     General                                                         29
     15.4     Property of Tenant                                              29
     15.5     Bursting of Pipes, etc.                                         30
     15.6     Repairs and Alterations - No Diminution                         30
              of Rental Value
     15.7     Landlord Indemnity of Tenant                                    32

16.  ASSIGNMENT, MORTGAGING AND SUBLETTING                                    32
     16.1     General Prohibition Against Transfers                           32
<PAGE>

     16.2     Landlord's Rights upon Tenant's Request for
              Sublet Consent                                                  33
     16.3     Transfer Consideration                                          33
     16.4     Transfer of Beneficial Interests in Tenant                      33
     16.5     Effect of Landlord's Consent to Transfer                        34
     16.6     Subleasing Prior to First Anniversary of Term
              Commencement Date                                               35

17.  MISCELLANEOUS COVENANTS                                                  34
     17.1     Rules and Regulations                                           34
     17.2     Access to Premises - Shoring                                    34
     17.3     Accidents to Sanitary and Other Systems                         35
     17.4     Signs, Blinds and Drapes                                        36
     17.5     Estoppel Certificate                                            36
     17.6     Prohibited Materials and Property                               36
     17.7     Requirements of Law - Fines and Penalties                       36
     17.8     Tenant's Acts - Effect on Insurance                             37
     17.9     Miscellaneous                                                   38

18.  DAMAGE BY FIRE, ETC.                                                     38
     18.1     Casualty Insurances                                             38
     18.2     Repair of Damage Caused by Casualty                             38
     18.3     Landlord's Termination Rights                                   39
     18.4     Tenant's Termination Rights                                     39
     18.5     General Provisions Relating to Any Casualty Termination         40

19.  WAIVER OF SUBROGATION                                                    40

20.  CONDEMNATION - EMINENT DOMAIN                                            41
     20.1     Landlord's Termination Rights                                   41
     20.2     Tenant's Termination Rights                                     41
     20.3     General Taking Provisions                                       41
     20.4     Taking Process                                                  42
     20.5     Temporary Takings                                               42

21.  DEFAULT                                                                  42
     21.1     Conditions of Limitation - Re-entry - Termination               42
     21.2     Damages - Assignment for Benefit of Creditors                   43
     21.3     Damages - Termination                                           44
     21.4     Fees and Expenses                                               45
     21.5     Waiver of Redemption                                            46
     21.6     Landlord's Remedies Not Exclusive                               46
     21.7     Grace Period                                                    46

22.  END OF TERM - ABANDONED PROPERTY                                         46

23.  SUBORDINATION                                                            48
<PAGE>


24.  QUIET ENJOYMENT                                                          50

25.  ENTIRE AGREEMENT  - WAIVER - SURRENDER                                   50
     25.1     Entire Agreement                                                50
     25.2     Waiver by Landlord                                              50
     25.3     Surrender                                                       51

26.  INABILITY TO PERFORM - EXCULPATORY CLAUSE                                51

27.  BILLS AND NOTICES                                                        52

28.  PARTIES BOUND - SEIZING OF TITLE                                         53

29.  MISCELLANEOUS                                                            53
     29.1     Separability                                                    53
     29.2     Captions, etc.                                                  53
     29.3     Broker                                                          54
     29.4     Governing Law                                                   54
     29.5     Assignment of Rents                                             54
     29.6     Representation of Authority                                     55
     29.7     Expenses Incurred by Landlord Upon Tenant Requests              55
     29.8     Survival                                                        55
<PAGE>

                                EXHIBITS

     Exhibit 1         Lease Data Exhibit
     Exhibit 2         Lease Plan
     Exhibit 3         Plan and Legal Description of Park
     Exhibit 4         Environmental Disclosure
     Exhibit 5         Building Services
     Exhibit 6         Form of Letter of Credit
     Rider
<PAGE>

         THIS INDENTURE OF LEASE made and entered into as of this ___ day of
_______ 2000, by and between VIALOG CORPORATION, a Massachusetts corporation
("Tenant") and EOP-CROSBY CORPORATE CENTER, L.L.C., a Delaware limited liability
company ("Landlord").

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

1.       REFERENCE DATA

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

2.       DESCRIPTION OF DEMISED PREMISES

         2.1 Demised Premises. The Premises are in the Building as described in
Exhibit 1, substantially as shown hatched or outlined on the Lease Plan, Exhibit
2 attached hereto and incorporated by reference as a part hereof.

         2.2 Park. The Building is located in the Park described in Exhibit 1,
which Park may be changed, increased or decreased by addition or subdivision of
parcels and/or by construction and/or demolition of buildings and/or other
improvements by Landlord from time to time, in accordance with the terms of this
Lease. If, during the term of the Lease, additional buildings are added to the
Park, then Tenant's Tax Percentage set forth in Exhibit 1 shall be revised to
include the Total Rentable Area of such building(s) at the earlier of (x) the
time that Landlord has received a certificate of occupancy for such building(s)
or (y) the date that real estate taxes are adjusted to reflect such additional
building(s).

         2.3 Appurtenant Rights. Tenant shall have, as appurtenant to the
Premises, rights to use in common, with others entitled thereto, subject to
reasonable rules governing use of the Park from time to time made by Landlord of
which Tenant is given prior written notice and with due regard for the rights of
others to use the same (a) the common roadways, sidewalks and walkways necessary
for the purposes of access to the Building from public road and walkways of the
Park and the loading docks for the Building, (b) such portions of the parking
areas of the Park, as may be designated by Landlord for common parking, for the
purpose of parking of motor vehicles by Tenant and Tenant's employees and
invitees, such parking to be provided to Tenant at a ratio of not in excess of
3.5 parking spaces per 1,000 square feet of the Total Rentable Area of the
Premises, the current location of which parking areas are shown on Exhibit 3 and
(c) any common area amenities of the Park (e.g., benches and lawns) for the
purposes for which the same are intended; and no other appurtenant rights or
easements. Subject to

                                      -1-
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Landlord's reasonable security requirements, Tenant shall have access to the
Premises 24 hours per day, 7 days per week.

         2.4 Exclusions and Reservations. Subject to the provisions of the Lease
(including, without limitation, Article 10), there is hereby expressly reserved
to Landlord (a) the right of access in and to the Premises for the purposes of
operation, maintenance, decoration and repair of the Premises, and (b) any space
in or adjacent to the Premises used for shafts, stacks, pipes, conduits, wires,
and appurtenant fixtures, fan rooms, ducts, electric and other utilities, sinks
or other Building facilities, in any case serving any other area(s) in the Park
and the use thereof. Notwithstanding anything to the contrary in the Lease
contained, Landlord and its agents, employees and contractors shall not, except
in an emergency and except for normal cleaning and maintenance operations,
exercise any right which it has to enter the Premises without giving Tenant
reasonable advance notice, and, in exercising any such right of access, Landlord
shall use reasonable efforts to minimize any interference with Tenant's use and
enjoyment of the Premises by Landlord.

3.       TERM OF LEASE

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

         (a) "Specified Commencement Date" - The date (as stated on Exhibit 1)
on which it is estimated that the Premises will be ready for Tenant's occupancy
for its use as stated in Exhibit 1.

         (b) "Term Commencement Date" - The "Term Commencement Date" is the date
on which the Premises are ready for Tenant's occupancy (as defined in Article
4.2) for use as set forth in Exhibit 1. If the Premises are not ready for such
occupancy but if, pursuant to permission therefor duly given by Landlord, Tenant
takes possession of the whole or any part of the Premises for business purposes
as set forth in Exhibit 1, "Term Commencement Date" shall be the date on which
Tenant takes such possession.

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

         3.3 Declaration Fixing Term Commencement Date. As soon as reasonably
practicable after the Execution Date hereof, each of the parties hereto agrees,
upon demand of the other party to join in the execution, in recordable form, of
a statutory notice, memorandum, etc. of lease and/or written declaration in
which shall be stated

                                      -2-
<PAGE>

such Term Commencement Date and (if need be) the Termination Date. If this Lease
terminates in accordance with its terms before the Termination Date stated in
Exhibit 1, then upon Landlord's request the parties shall execute, deliver and
record an instrument acknowledging such fact and the date of termination of this
Lease.

4.       CONDITION OF PREMISES

         4.1 Completion Date - Delays.

         Subject to delay by causes beyond the reasonable control of Landlord or
caused by the action or inaction of Tenant, Landlord shall use reasonable speed
and diligence to have the Premises ready for Tenant's occupancy on the Specified
Commencement Date. The failure to have the Premises ready for Tenant's occupancy
on the Specified Commencement Date shall in no way affect the validity of this
Lease or the obligations of Tenant hereunder nor shall the same be construed in
any way to extend the term of this Lease. If the Premises are not ready for
Tenant's occupancy within the meaning of Article 4.2 hereof on the Specified
Commencement Date, Tenant shall not have any claim against Landlord, and
Landlord shall have no liability to Tenant, by reason thereof. Notwithstanding
the foregoing, if the Term Commencement Date shall not have occurred on or
before the Outside Date, as hereinafter defined, then Tenant shall have the
right, exercisable by a written thirty (30) day termination notice given on or
after the Outside Date, to terminate the Lease. If the Term Commencement Date
occurs on or before the thirtieth (30th) day after Landlord receives such
termination notice, Tenant's termination notice shall be deemed to be void and
of no force or effect. If the Term Commencement Date does not occur on or before
such thirtieth (30th) day, this Lease shall terminate and shall be of no further
force or effect. For the purposes hereof, the "Outside Date" shall be defined as
the date ninety (90) days after the Specified Commencement Date, provided
however, that the Outside Date shall be extended by the length of any delays in
Landlord's Work arising from causes beyond Landlord's reasonable control (see
Article 26)

         4.2 When Premises Deemed Ready.

         The Premises shall be conclusively deemed ready for Tenant's occupancy
as soon as (i) Landlord's Work, as defined in Article 4.2A, has been
substantially completed by Landlord insofar as is practicable in view of delays
or defaults, if any, of Tenant or its contractors, as hereinafter specified,
(ii) the elevator, plumbing, air conditioning and electric facilities are
initially substantially available to Tenant, in accordance with the obligations
assumed by Landlord hereunder, (iii) the earlier of (x) the date that Landlord
receives a temporary or permanent certificate of occupancy allowing Tenant to
occupy the Premises or (y) the date that Landlord would have received such
certificate absent any Tenant Delays, as hereinafter defined, and (iv) access
through the common areas of the Building to the Premises is provided. Such
facilities shall not be deemed to be unavailable if only minor or insubstantial
details of construction, decoration or mechanical adjustments remain to be done.
The Premises shall not be deemed to be unready for Tenant's occupancy or
incomplete if only minor or insubstantial details of

                                      -3-
<PAGE>

construction, decoration or mechanical adjustments remain to be done in the
Premises or any part thereof, or if the delay in the availability of the
Premises for occupancy is due to any of the following (referred to collectively
as "Tenant Delays"): (i) due to special work, changes, alterations or additions
required or made by Tenant in the layout or finish of the Premises or any part
thereof, (ii) caused in whole or in part by Tenant through the delay of Tenant
in submitting Tenant's final approved plans on or before the Final Plans Date in
accordance with Article 4.3(c), (iii) caused in whole or in part by Tenant
through the delay of Tenant in supplying information, approving plans,
specifications or estimates, giving authorizations or otherwise or (iv) caused
in whole or in part by delay and/or default on the part of Tenant or its
contractors including, without limitation, the utility companies and other
entities furnishing communications, data processing or other service or
equipment. Notwithstanding the foregoing, if Landlord fails to notify Tenant of
any Tenant Delay addressed in clauses (i), (iii) or (iv) in the immediately
preceding sentence within two (2) days after the date Landlord knew of such
Tenant Delay, Tenant shall not be responsible for any such Tenant Delay with
respect to the period of time commencing three (3) days after the date when
Landlord knew that such Tenant Delay existed and ending on the date that
Landlord notified Tenant of such Tenant Delay. If the Premises are deemed ready
for Tenant's occupancy, pursuant to the foregoing, (and the term shall have
commenced by reason thereof), but the Premises are not in fact actually ready
for Tenant's occupancy, Tenant shall not (except with Landlord's consent) be
entitled to take possession of the Premises for use as set forth in Exhibit 1
until the Premises are in fact actually ready for such occupancy. Landlord's
architect's certificate of substantial completion, as hereinabove stated, given
in good faith, or of any other facts pertinent to this Article 4.2 shall be
deemed conclusive of the statements therein contained and binding upon Tenant,
unless Tenant gives written notice to Landlord objecting to such certificate
within fourteen (14) days after Landlord delivers such certificate of
substantial completion, setting forth with specificity Tenant's objections to
such certificate. Any of Landlord's Work in the Premises not fully completed on
the Term Commencement Date shall thereafter be so completed with reasonable
diligence by Landlord.

         4.2A Definition of Landlord's Work

         (i)  Landlord shall perform the work ("Landlord's Work") shown on the
Tenant's Plans, as defined in Article 4.3, in order to prepare the Premises for
Tenant's occupancy, using Building standard materials.

         (ii) Payment for the Cost of Landlord's Work. The cost of Landlord's
Work shall be paid as follows. Landlord shall contribute an amount ("Landlord's
Contribution") of up to Twenty-Two and 00/100 ($22.00) Dollars per square foot
of Total Rentable Area of the Premises towards the cost of Landlord's Work, plus
an amount (Landlord's HVAC Contribution") of up to Three and 50/100 ($3.50)
Dollars per square foot of Total Rentable Area of the Premises towards the cost
of installing a heating, air conditioning and ventilation system to serve the
Premises. Tenant shall have the right to apply any unused portion of Landlord's
Contribution and Landlord's HVAC Contribution towards architectural and
engineering fees incurred by Tenant in connection with Landlord's Work, towards
wiring and cabling costs incurred by Tenant in the Premises

                                      -4-
<PAGE>

towards moving costs incurred by Tenant in moving to the Premises and towards
the cost of Tenant's signs as described in Article 17.4, all upon Landlord's
receipt of paid invoices evidencing such costs. Except as set forth in the
immediately preceding sentence, Tenant shall have no right to use any unused
portion of Landlord's Contribution or Landlord's HVAC Contribution. Tenant shall
be fully responsible for the entire cost of Landlord's Work in excess of
Landlord's Contribution and Landlord's HVAC Contribution, other than the cost of
change orders not requested by Tenant. Tenant shall pay such cost within fifteen
(15) business days of billing therefor. Without limiting any other remedy
Landlord may have, Tenant's failure to pay any such amounts shall be considered
to be a Tenant Delay. In the event Landlord's estimate and/or the actual cost of
Landlord's Work shall exceed the sum of Landlord's Contribution and Landlord's
HVAC Contribution, Landlord, prior to commencing any construction of Landlord
Work, shall submit to Tenant a written estimate setting forth the anticipated
cost of the Landlord Work, including but not limited to labor and materials,
contractor's fees and permit fees. Within three (3) business days thereafter,
Tenant shall either notify Landlord in writing of its approval of the cost
estimate, or specify its objections thereto and any desired changes to the
proposed Landlord Work. In the event Tenant notifies Landlord of such objections
and desired changes, Tenant shall work with Landlord to reach a mutually
acceptable alternative cost estimate.

         4.3 Plans and Specifications

         (a) Tenant's Plans. Tenant shall be solely responsible for the timely
preparation and submission to Landlord of the final architectural, electrical
and mechanical construction drawings, plans and specifications (called "Tenant
Plans") necessary to construct the Premises for Tenant's occupancy, which plans
shall be subject to Landlord's approval and shall comply with Landlord's
requirements to avoid aesthetic or other conflicts with the design and function
of the balance of the Building.

         (b) Landlord's Approval of Tenant's Plans. Landlord agrees that it will
not unreasonably withhold its consent to Tenant's Plans. Landlord's approval is
solely given for the benefit of Landlord and neither Tenant nor any third party
shall have the right to rely upon Landlord's approval of Tenant's plans for any
purpose whatsoever, except for compliance with Section 4.3(a). Without limiting
the foregoing: (i) Tenant shall be responsible for all elements of the design of
Tenant's plans (including, without limitation, compliance with law,
functionality of design, the structural integrity of the design, the
configuration of the Premises and the placement of Tenant's furniture,
appliances and equipment), (ii) Landlord's approval of Tenant's plans shall in
no event relieve Tenant of the responsibility for such design, and (iii)
Landlord shall have no responsibility for the adequacy of the design of the HVAC
System serving the Premises for Tenant's use (Tenant acknowledging that Tenant
is relying upon its own architects and engineers in determining whether to
modify the HVAC equipment which serves the Premises as of the Term Commencement
Date).

         (c) Cost of Tenant's Plans. If requested by Tenant, Landlord's
architect will prepare the plans necessary for Landlord's Work at Tenant's cost
(including charges for

                                      -5-
<PAGE>

not only building standard work, but also for special services of the Landlord's
architect and engineer not included in the design of space for occupancy using
building standard partitioning, floors, ceiling and mechanical and electrical
service). Such special services shall include, but not be limited to, design of
built-in equipment, interior design embracing materials and finishes other than
building standard, design of private lavatories and other special purpose rooms
and interior decorating. Whether or not the layout and plans are prepared with
the help (in whole or in part) of Landlord's architect, Tenant agrees to remain
solely responsible for the timely preparation and submission of all of Tenant's
plans and for all elements of the design of such plans and for all costs related
thereto, subject to Landlord's Plans Contribution and Landlord's Contribution.
Tenant has assured itself by direct communication with the architect and
engineers (Landlord's or its own, as the case may be) that the final approved
plans can be delivered to Landlord on or before the Final Plans Date as stated
in Exhibit 1, provided that Tenant promptly furnishes complete information
concerning its requirements to said architect and engineers as and when
requested by them; and Tenant covenants and agrees to cause said final, approved
plans and specifications to be delivered to Landlord on or before said Final
Plans Date and to devote such time as may be necessary in consultation with said
architect and engineers to enable them to complete and submit all plans within
the required time limit. Time is of the essence in respect of preparation and
submission of plans by Tenant. (The word "architect" as used in this Article 4
shall include an interior designer or space planner.) Notwithstanding the
foregoing, Landlord shall contribute, in addition to Landlord's Contribution and
Landlord's HVAC Contribution, an amount ("Landlord's Plans Contribution") up to
Two and 00/100 ($2.00) per square foot of Total Rentable Area of the Premises
toward the cost of Tenant's Plans. Tenant shall have no right to use any unused
portion of Landlord's Plans Contribution. Landlord shall pay Landlord's Plans
Contribution to Tenant within thirty (30) days after Tenant submits to Landlord
monthly invoices therefor, provided that such invoices include evidence of the
costs so incurred by Tenant.

         4.4 Preparation of Premises.

         (a) By Landlord. Except as is otherwise herein provided or as may be
otherwise approved by the Landlord, all work necessary to prepare the Premises
for Tenant's occupancy, including work to be performed at Tenant's expense,
shall be performed by contractors employed by Landlord. Landlord agrees to bid
Landlord's Work to 3 general contractors and to share such bids with Tenant.
Landlord shall select the lowest bid received unless Landlord has a reasonable
reason for not selecting the lowest bidder, in which event Landlord shall advise
Tenant thereof. Landlord agrees to keep Tenant advised as to the status of
Landlord's Work by providing to Tenant copies of invoices, consulting with
Tenant on the management of Landlord's Work and permitting Tenant to attend and
participate in construction meetings for Landlord's Work.

         (b) By Tenant. Tenant shall engage its own contractor to install cable
for its telecommunications and computer systems in the Premises. Subject always
to the provisions of Articles 4.2 and 4.3, if Tenant engages any contractors to
perform work in preparing the Premises for Tenant's occupancy, Landlord will
give Tenant reasonable

                                      -6-
<PAGE>

advance notice of the date on which the Premises will be ready for such other
contractors and a reasonable time (which shall be not less than thirty (30)
days) will be allowed from such date for doing the work to be performed by such
other contractors.

         (c) Cooperation of Tenant's Contractor. If any work, including but not
by way of limitation, installation of built-in equipment by the manufacturer or
distributor thereof, shall be performed by contractors not employed by Landlord,
Tenant shall take necessary reasonable measures to the end that such contractor
shall cooperate in all ways with Landlord's contractors to avoid any delay to
the work being performed by Landlord's contractors or conflict in any other way
with the performance of such work.

         4.5 Cost of Materials. Except for Landlord's Contribution, Landlord's
HVAC Contribution and Landlord's Plans Contribution, Tenant shall bear all other
costs of preparing the Premises for its occupancy (including, without
limitation, the cost of any changes to the Plans).

         4.6 Tenant Delay - Additional Costs. In the event of any Tenant Delays,
any additional cost to Landlord in connection with the completion of the
Premises in accordance with the terms of this Lease shall be promptly paid by
Tenant to Landlord if such additional cost is in whole or in part the result of
such failure, omission or delay of Tenant. For the purposes of the next
preceding sentence, the expression "additional cost to Landlord" shall mean the
cost over and above such cost as would have been the aggregate cost to Landlord
of completing the Premises in accordance with the terms of this Lease had there
been no such failure, omission or delay. Nothing contained in this Article 4.6
shall limit or qualify or prejudice any other covenants, agreements, terms,
provisions and conditions contained in this Lease, including but not limited to
Article 4.2.

         4.7 Entry by Tenant Prior to Term Commencement Date. With Landlord's
prior written consent, which shall not be unreasonably withheld, Tenant shall
have the right to enter the Premises at least thirty (30) days prior to the Term
Commencement Date, during normal business hours and without payment of rent, to
perform such work or decoration as is to be performed by, or under the direction
or control of, Tenant and as is otherwise in compliance with the terms of this
Lease. Such right of entry shall be deemed a license from Landlord to Tenant,
and any entry thereunder shall be at the risk of Tenant. In addition, Tenant
shall have the right, after Tenant executes and delivers this Lease to Landlord,
without payment of rent, to enter the Premises for the purposes of preparing
Tenant's plans in connection with Landlord's Work, provided that Tenant does not
interfere with the performance of Landlord's Work in the Premises.

         4.8 Conclusiveness of Landlord's Performance. With respect to any
patent defects in Landlord's Work, Tenant shall be conclusively deemed to have
agreed that Landlord has performed all of its obligations under this Article 4
unless not later than the end of the third calendar month next beginning after
the Term Commencement Date Tenant shall give Landlord written notice specifying
the respects in which Landlord has not performed any such obligation. With
respect to latent defects in any portion of Landlord's Work, Tenant shall be
conclusively deemed to have agreed that Landlord has

                                      -7-
<PAGE>

performed all of its obligations under this Article 4 unless, not later than the
date eleven (11) months after the date Landlord substantially completes
Landlord's Work, Tenant shall give written notice to Landlord specifying the
respects in which Landlord has not performed any such obligation. Landlord, at
its option, may pursue such claims directly against the contractors or
subcontractors or assign any such warranties to Tenant for enforcement.

         4.9 Tenant Payments of Construction Cost. Landlord shall have the same
rights and remedies which Landlord has upon the nonpayment of Yearly Rent and
other charges due under this Lease for nonpayment of any amounts which Tenant is
required to pay to Landlord or Landlord's contractor in connection with the
construction and initial preparation of the Premises (including, without
limitation, any amounts which Tenant is required to pay in accordance with
Articles 4.5 and 4.6 hereof) or in connection with any construction in the
Premises performed for Tenant by Landlord, Landlord's contractor or any other
person, firm or entity after the Term Commencement Date.

5.       USE OF PREMISES

         5.1 Permitted Use. Tenant shall during the term hereof occupy and use
the Premises only for the purposes as stated in Exhibit 1 and for no other
purposes. Utility areas (whether or not a part of the Premises) shall be used
only for their intended purpose. Subject to the other terms and provisions of
this Lease, Tenant shall be permitted to install and operate any kitchen
equipment shown on Tenant's Final Plans, and equivalent substitutions therefor,
provided that, and so long as, the same are maintained in good operating
condition. Such kitchen equipment may be used only for the purposes of serving
Tenant's employees and business invitees.

         5.2 Prohibited Uses. Notwithstanding any other provision of this Lease,
Tenant shall not use, or suffer or permit the use or occupancy of, or suffer or
permit anything to be done in or anything to be brought into or kept in or about
the Premises, the Building, the Park or any part thereof: (i) which would
violate any of the covenants, agreements, terms, provisions and conditions of
this Lease, (ii) for any unlawful purposes or in any unlawful manner; (iii)
which, in the reasonable judgment of Landlord shall in any way (a) materially
impair the exterior appearance of the Building or the Park; or (b) materially
impair, interfere with or otherwise diminish the quality of any of the Building
services or the heating, cleaning, air conditioning or other servicing of the
Building or Premises, or with the use or occupancy of any of the other areas of
the Building or the Park, or occasion material interruption to the quiet
enjoyment of, or injury or damage to any occupants of the Premises or other
tenants or occupants of the Building or the Park; or (iv) which is materially
inconsistent with the maintenance of the Building and/or the Park as facilities
comparable to first-class office/research and development buildings in the
Market Area, as defined in Article 8.3, in the quality of their maintenance,
use, or occupancy.

         5.3 Licenses and Permits. If any governmental license or permit shall
be required for the proper and lawful conduct of Tenant's business, and if the
failure to

                                      -8-
<PAGE>

secure such license or permit would in any way adversely affect Landlord, the
Premises, the Building, the Park or Tenant's ability to perform any of its
obligations under this Lease, Tenant, at Tenant's expense, shall duly procure
and thereafter maintain such license and submit the same to inspection by
Landlord. Tenant, at Tenant's expense, shall at all times comply with the terms
and conditions of each such license or permit.

         5.4 Vacancy by Tenant. If Tenant shall cease using all or substantially
all of the Premises for a period ("Vacancy Period") of one hundred twenty (120)
consecutive days, then Landlord shall have the right, exercisable by written
notice given to Tenant at any time after the Vacancy Period, but prior to the
time that Tenant again recommences its use of the Premises to terminate this
Lease. Such termination of the Lease shall be effective on the date thirty (30)
days after Landlord's termination notice is given, unless Tenant recommences its
use of the Premises before the end of such thirty (30) period, in which event
this Lease shall continue in full force and effect. Vacancy by Tenant shall not
be considered to be a default by Tenant and Landlord shall not be entitled to
any damages from Tenant on account of any termination under this Article 5.4.

6.       RENT

         6.1 In General. During the term of this Lease the Yearly Rent, Tax
Excess, Operating Expense Excess, if applicable (collectively, "Rent") at the
rate stated in Exhibit 1, shall be payable by Tenant to Landlord by monthly
payments, as stated in Exhibit 1, in advance and without demand on the first day
of each month for and in respect of such month. Tenant's obligation to pay the
rent shall commence in accordance with Article 6.2 below. If, by reason of any
provisions of this Lease, the Rent shall commence or terminate on any day other
than the first day of a calendar month, the Rent for such calendar month shall
be prorated. The Rent shall be payable to Landlord or, if Landlord shall so
direct in writing, to Landlord's agent or nominee, in lawful money of the United
States which shall be legal tender for payment of all debts and dues, public and
private, at the time of payment, at the office of the Landlord or such place as
Landlord may designate, and the Rent and other charges in all circumstances
shall be payable without any setoff or deduction whatsoever, except as otherwise
expressly provided herein and only to that extent. Rent and any other sums due
hereunder not paid within ten (10) days after the date due shall bear interest
for each month or fraction thereof from the due date until paid computed at the
annual rate of two percentage points over the so-called prime rate then
currently from time to time published in the Wall Street Journal, (or if the
                                             ---- ------ -------
Wall Street Journal ceases to publish a prime rate, then the prime rate charged
---- ------ -------
to its most favored corporate customers by the largest national bank (N.A.
located in the City of Boston) or at any applicable lesser maximum legally
permissible rate for debts of this nature ("Lease Rate").

         6.2 Commencement of Rent. Tenant's obligation to pay Rent shall
commence on the Term Commencement Date.

         6.3 Rentable Area. Landlord and Tenant acknowledge the Total Rentable
Area of the Premises and of all other buildings in the Park were measured in
accordance

                                      -9-
<PAGE>

with the New York Measurement Standard and have been determined by
agreement to be as set forth in Exhibit 1 attached hereto for the purposes of
this Lease and that the figures set forth therein shall be conclusive and
binding on Landlord and Tenant with regard to the Park as it exists as of the
Execution Date, provided that if any building is physically expanded, the Total
Rentable Area of such building and of the Park shall be appropriately increased
using the same methodology as was used to arrive at the figures in Exhibit 1
before said expansion.

7.       HAZARDOUS MATERIALS

         Landlord and Tenant agree as follows with respect to the existence or
use of "Hazardous Material" in or on the Premises.

         (a) Tenant, at its sole cost and expense, shall comply with all laws,
statutes, ordinances, rules and regulations of any local, state or federal
governmental authority having jurisdiction concerning environmental, health and
safety matters (collectively, "Environmental Laws"), including, but not limited
to, any discharge into the air, surface, water, sewers, soil or groundwater of
any Hazardous Material (as defined in Article 7(c)), whether within or outside
the Premises within the Park. Notwithstanding the foregoing, nothing contained
in this Lease requires, or shall be construed to require, Tenant to incur any
liability related to or arising from environmental conditions not introduced or
caused by Tenant or those for whom Tenant is responsible or for which the
Landlord is responsible pursuant to the terms of this Lease.

         (b) Tenant shall not cause or permit any Hazardous Material to be
brought upon, kept or used in or about the Premises or otherwise in the Park by
Tenant, its agents, employees, contractors or invitees, without the prior
written consent of Landlord, except for Hazardous Materials which are typically
used in the operation of offices provided that the same shall at all times be
brought upon, kept or used in accordance with all applicable Environmental Laws.
Notwithstanding the foregoing, with respect to any of Tenant's Hazardous
Material which Tenant does not properly handle, store or dispose of in
compliance with all applicable Environmental Laws, Tenant shall, upon written
notice from Landlord, no longer have the right to bring such material into the
buildings or the Park until Tenant has demonstrated, to Landlord's reasonable
satisfaction, that Tenant has implemented programs to thereafter properly
handle, store or dispose of such material.

         (c) As used herein, the term "Hazardous Material" means any hazardous
or toxic substance, material or waste or petroleum derivative which is or
becomes regulated by any Environmental Law. The term "Hazardous Material"
includes, without limitation, any material or substance which is (i) designated
as a "hazardous substance" pursuant to Section 1311 of the Federal Water
Pollution Control Act (33 U.S.C. Section 1317), (ii) defined as a hazardous
waste" pursuant to Section 1004 of the Federal Resource Conservation and
Recovery Act, 42 U.S.C. Section 6901 et seq. (42 U.S.C. Section 6903), or (iii)
defined as a "hazardous substance" pursuant to Section 101 of the Comprehensive
Environmental Response, Compensation and Liability Act, 42 U.S.C. Section 9601
et seq. (42 U.S.C. Section 9601) or (iv) defined as "hazardous substance" or

                                      -10-
<PAGE>

"oil" under Chapter 21E of the General Laws of Massachusetts, and "Environmental
Laws" include, without limitation, the laws listed in the preceding clauses (i)
through (iv).

         (d) Any increase in the premium for necessary insurance on the Premises
or the Park which arises from Tenant's use and/or storage of these Hazardous
Materials shall be solely at Tenant's expense. Tenant shall procure and maintain
at its sole expense such additional insurance as may be necessary to comply with
any requirement of any Federal, State or local government agency with
jurisdiction.

         (e) Tenant hereby covenants and agrees to indemnify, defend and hold
Landlord harmless from any and all claims, judgments, damages, penalties, fines,
costs, liabilities or losses (collectively "Losses") which Landlord may
reasonably incur arising out of contamination of real estate, the Park or other
property not a part of the Premises, which contamination arises as a result of:
(i) the presence of Hazardous Material in the Premises, the presence of which is
caused or permitted by Tenant, or (ii) from a breach by Tenant of its
obligations under the first two sentences of Article 7(b). This indemnification
of Landlord by Tenant includes, without limitation, reasonable costs incurred in
connection with any investigation of site conditions or any cleanup, remedial,
removal or restoration work required by any federal, state or local governmental
agency or political subdivision because of Hazardous Material present in the
soil or ground water on or under the Premises based upon the circumstances
identified in the first sentence of this Article 7(e). The indemnification and
hold harmless obligations of Tenant under this Article 7(e) shall survive any
termination of this Lease. Without limiting the foregoing, if the presence of
any Hazardous Material in the buildings or otherwise in the Park caused or
permitted by Tenant results in any contamination of the Premises, Tenant shall
promptly take all actions at its sole expense as are necessary to return the
Premises to a condition which complies with all Environmental Laws; provided
that Landlord's approval of such actions shall first be obtained, which approval
shall not be unreasonably withheld so long as such actions, in Landlord's
reasonable discretion, would not potentially have any materially adverse
long-term or short-term effect on the Premises, and, in any event, Landlord
shall not withhold its approval of any proposed actions which are required by
applicable Environmental Laws.

         (f) Landlord represents to Tenant that, to the best of Landlord's
knowledge, (Landlord representing to Tenant that Landlord has previously engaged
consultants to determine the existence of Hazardous Materials in the Park) there
are no Hazardous Materials (including asbestos) or underground storage tanks
presently located in the Park, except as described on Exhibit 4. Landlord
further represents to Tenant that, as of the Execution Date, there is no
asbestos located in the Premises, except as described on Exhibit 4. Landlord
shall take any action required by law (including, if necessary, implementation
of air monitoring and/or abatement procedures) in connection with the Hazardous
Materials and asbestos referenced on Exhibit 4.

         (g) Landlord agrees that neither Landlord, nor its agents, employees or
contractors, shall cause or permit any Hazardous Materials (other than materials
which

                                     -11-
<PAGE>

are typically used in the operation of offices) to be brought upon, kept, or
used in or about the Park. Landlord shall use reasonable efforts to prevent
other tenants from bringing, keeping or using hazardous materials in or about
the Park.

         (h) Landlord hereby covenants and agrees to indemnify, defend and hold
Tenant harmless from any Losses which arise from: (1) any matters disclosed on
Exhibit 4; (2) any breach by Landlord of the representations set forth in
Article 7(f) above; and (3) any breach by Landlord of its agreements under
Article 7(g) above provided that Landlord shall have no liability to Tenant in
the event of a breach by another tenant of the Park of its obligations with
respect to Hazardous Materials other than to use reasonable efforts to cause
such tenant, without cost to Tenant, to remove such Hazardous Materials from the
Park, at the time, and in the manner required by law. The indemnification and
hold harmless provisions of this Article 7(h) shall survive any termination of
this Lease.

         (i) Landlord further agrees that if Tenant suffers a loss (including,
without limitation, reasonable attorneys fees) as the result of Hazardous
Materials which are introduced into the Park by another tenant of the Park,
Landlord shall use reasonable efforts to enforce its rights against such tenant
to enable Tenant to recover such loss from such tenant. The provisions of this
Article 7(i) shall survive any termination of this Lease.

8.       SERVICES FURNISHED BY LANDLORD

         8.1 Electric Current.

         (a) The parties acknowledge and agree that the consumption of
electricity for outlet plug use and supplemental (i.e., installed as part of
Landlord's Work, installed in the Premises subsequent to the Term Commencement
Date by Tenant, or installed in accordance with Article 8.6) HVAC in the
Premises will be measured by a separate sub-meter to be installed as part of the
Landlord's Work, and maintained by Landlord, provided that electricity for the
operation of the non-submetered (i.e., base building) HVAC system serving the
Premises and parking lot lighting in the Park shall not be connected to such
submeter. Landlord shall pay directly to the utility for electricity consumed by
Tenant in the Premises and Tenant shall reimburse Landlord for the entire cost
of the sub-metered electric current as follows:

              (1) Commencing as of the Term Commencement Date and continuing
         until the procedures set forth in Paragraph 2 of this Article 8.1(a)
         are effected, Tenant shall pay to Landlord at the same time and in the
         same manner that it pays its monthly payments of Yearly Rent hereunder,
         estimated monthly payments on account of Tenant's obligation to
         reimburse Landlord for electricity consumed in the Premises.

             (2) Monthly after the Term Commencement Date, Landlord shall
         determine the actual cost of electricity consumed by Tenant in the
         Premises (i.e., by reading Tenant's sub-meter and by applying the
         actual Electric Rate(s)

                                     -12-
<PAGE>

         applicable to the preceding period). If the total of Tenant's estimated
         monthly payments on account of such period is less than the actual cost
         of electricity consumed in the Premises during such period, Tenant
         shall pay the difference to Landlord within thirty (30) days after
         receipt of Landlord's bill therefor. If the total of Tenant's estimated
         monthly payments on account of such period is greater than the actual
         cost of electricity consumed in the Premises during such period, Tenant
         may credit the difference against its next installment of rental or
         other charges due hereunder, except that if such difference is
         determined after the end of the term of the Lease, Landlord shall
         refund such difference to Tenant to the extent that such difference
         exceeds any amounts then due from Tenant to Landlord.

             (3) After each adjustment, as set forth in Paragraph (2) above, the
         amount of estimated monthly payments on account of Tenant's obligation
         to reimburse Landlord for electricity in the Premises shall be adjusted
         based upon the actual cost of electricity consumed during the
         immediately preceding period.

         (b) If Tenant shall require electric current for use in the Premises in
excess of the capacity of the Building electrical system (which capacity is
277/480 volt service), and if (i) in Landlord's reasonable judgment, Landlord's
facilities are inadequate for such excess requirements or (ii) such excess use
shall result in an additional burden on the Building air conditioning system and
additional cost to Landlord on account thereof then Landlord upon written
request and at the sole cost and expense of Tenant, will furnish and install
such additional wire, conduits, feeders, switchboards and appurtenances as
reasonably may be required to supply such additional requirements of Tenant if
current therefor be available to Landlord, provided that the same shall be
permitted by applicable laws and insurance regulations and shall not cause
damage to the Building or the Premises or cause or create a dangerous or
hazardous condition or entail excessive or unreasonable alterations or repairs
or which materially interfere with the quiet enjoyment of the other tenants or
occupants of the Park. Tenant shall have the right to use electric current in
the Premises 24 hours per day, 7 days per week, which electric current shall be
paid for by Tenant in accordance with Article 8.1(a).

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

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

         (e) Tenant agrees that it will not make any material alteration or
material addition to the electrical equipment and/or appliances in the Premises
without the prior

                                     -13-
<PAGE>

written consent of Landlord in each instance first obtained, which consent will
not be unreasonably withheld.

         8.2 Water. Landlord, at its expense, subject to the inclusion of such
expenses in Operating Costs, shall furnish hot and cold water for ordinary
office purposes and for cleaning, toilet, lavatory, and drinking purposes. If
Tenant requires, uses or consumes water for any purpose other than for the
aforementioned purposes, Landlord may (i) assess a reasonable charge for the
additional water so used or consumed by Tenant or (ii) install a water meter and
thereby measure Tenant's water consumption for all purposes. Tenant shall pay
the cost of the meter and the cost of installation thereof and shall keep said
meter and installation equipment in good working order and repair. Tenant agrees
to pay for water consumed, as shown by said meter, together with the sewer
charge based on said meter charges, within thirty (30) days after receipt of
Landlord's bill therefor, and on default in making such payment, Landlord may
pay such charges and collect the same from Tenant.

         8.3 Heat and Cleaning.

         Landlord at its expense, subject to the inclusion of such expenses in
Operating Costs, shall: (i) furnish heat (substantially equivalent to that being
furnished in comparably aged similarly equipped first class suburban
office/research and development buildings in the greater Burlington, Lexington
and Bedford submarket ("Market Area")) to the Premises during the normal heating
season and as normal seasonal changes may require on Mondays through Fridays,
excepting legal holidays, from 8:00 a.m. to 6:00 p.m. and on Saturdays,
excepting legal holidays, from 8:00 a.m. to 1:00 p.m. (called "business days")
and (ii) cause the office areas of the Premises to be cleaned in accordance with
the provisions of Section 8.5 on business days (except on Saturdays) in
accordance with the cleaning standards attached as Exhibit 5, provided the same
are kept in reasonable order by Tenant.

         8.4 Air Conditioning. Landlord shall at its expense, subject to the
inclusion of such expenses in Operating Costs, furnish to and distribute in the
Premises air conditioning substantially equivalent to that being furnished in
comparably aged similarly equipped first class suburban office/research and
development buildings, as normal seasonal changes may require, on business days
during the hours as aforesaid in Article 8.3 when air conditioning may
reasonably be required for the comfortable occupancy of the Premises by Tenant.
The parties acknowledge that the so-called 24 hour "call center" of the Premises
shall be served by a separate air-conditioning system to be installed as part of
the Landlord's Work. Tenant agrees to lower and close the blinds or drapes when
necessary because of the sun's position, whenever the air conditioning system is
in operation; provided, however, that Tenant's failure to comply with the
foregoing shall not be a default hereunder. Tenant further agrees to cooperate
fully with Landlord with regard to, and to abide by all the reasonable
regulations and requirements which Landlord may prescribe for the proper
functioning and protection of the air conditioning system.

                                     -14-
<PAGE>

         8.5 Additional Heat, Cleaning and Air Conditioning Services.

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

         (b) Tenant will pay to Landlord a reasonable charge (i) for any such
additional heat, cleaning or air conditioning service required by Tenant for the
Overtime Hours, (ii) for any extra cleaning of the Premises required because of
Tenant's 24 hour "call-center" or because of the gross carelessness of Tenant
and (iii) for any cleaning beyond the requirements of Exhibit 5 done at the
request of Tenant of any portions of the Premises which may be used for storage,
shipping room or other non-office purposes. If the cost to Landlord for cleaning
the Premises shall be increased due to the installation in the Premises, at
Tenant's request, of any materials or finish other than as set forth in Exhibit
5, Tenant shall pay to Landlord an amount equal to such increase in cost.

         8.6 Additional Air Conditioning Equipment.

         In the event Tenant requires additional air conditioning for business
machines, meeting rooms or other special purposes, or because of occupancy or
excess electrical loads or any additional air conditioning units, chillers,
condensers, compressors, ducts, piping and other equipment, then such additional
air conditioning equipment will be installed and maintained by Landlord at
Tenant's sole cost and expense, but only if, in Landlord's reasonable judgment,
the same will not cause damage or injury to the Building or create a dangerous
or hazardous condition or entail excessive or unreasonable alterations, repairs
or expense or interfere with or disturb other tenants; and Tenant shall
reimburse Landlord in such an amount as will compensate it for the actual cost
(including depreciation associated with the equipment needed to bring in such
additional air conditioning and electrical service) incurred by it in operating
such additional air conditioning equipment.

         8.7 Repairs. Except as otherwise provided in Articles 18 and 20, and
subject to Tenant's obligations in Article 14, Landlord shall, at its expense,
subject to the inclusion of such expenses in Operating Costs, keep and maintain,
repair and replace as necessary the roof, exterior walls, exterior windows,
structural floor slabs, columns, elevators, public stairways and corridors,
lavatories, equipment (including, without limitation, sanitary, electrical,
heating, ventilation, air conditioning, or other systems) and other common
facilities of the Premises, the Building and the Park, including, without
limitation, all parking area lighting, signage and sewer facilities, in good
condition and repair, and shall maintain all lawns and planted areas in the Park
and keep in good repair and condition all surfaced roadways, walks, and parking
and loading areas which Tenant has a right to use under this Lease, and shall
keep the same clear and free of snow and ice as necessary.

                                     -15-
<PAGE>

         8.8 Interruption or Curtailment of Services.

         (a) When necessary by reason of accident or emergency, or for repairs,
alterations, replacements or improvements to the Premises and/or the Park which
in the reasonable judgment of Landlord are desirable or necessary to be made, or
by reason of difficulty or inability in securing supplies or labor, or of
strikes, or of any other cause beyond the reasonable control of Landlord,
whether such other cause be similar or dissimilar to those hereinabove
specifically mentioned, until said cause has been removed, Landlord reserves the
right to interrupt, curtail, stop or suspend (i) the furnishing of heating,
elevator, air conditioning, and cleaning services and (ii) the operation of the
plumbing and electric systems. Landlord shall use its best efforts to eliminate
the cause of any such interruption, curtailment, stoppage or suspension, but,
subject to Paragraphs (b) and (c) of this Article 8.8, there shall be no
diminution or abatement of Yearly Rent or other compensation due from Tenant to
Landlord hereunder, nor shall this Lease be affected or any of the Tenant's
obligations hereunder reduced, and the Landlord shall have no responsibility or
liability for any such interruption, curtailment, stoppage, or suspension of
services or systems. Landlord shall, except in an emergency or accident, give
Tenant advance notice of any interruption in Building services.

         (b) Notwithstanding anything to the contrary in this Lease contained,
if the Premises shall lack any service which Landlord is required to provide
hereunder (thereby rendering the Premises or a portion thereof untenantable) for
a period of three (3) consecutive days after Landlord's receipt of written
notice from Tenant of such condition, the untenantability of which substantially
adversely affects the continued operation in the ordinary course of Tenant's
business, then, provided that such untenantability and Landlord's inability to
cure such condition is not caused by the fault or neglect of Tenant or Tenant's
agents, employees or contractors, or causes beyond Landlord's reasonable control
(excluding financial inability to perform obligations), Yearly Rent, Operating
Expense Excess and Tax Excess shall be abated in proportion to such
untenantability from the date such notice is received by Landlord until the day
such condition is completely corrected.

         (c) Notwithstanding anything to the contrary in this Lease contained,
if the Premises shall lack any service which Landlord is required to provide
hereunder (thereby rendering the Premises or a portion thereof untenantable) for
a period of ten (10) consecutive days after Landlord's receipt of written notice
from Tenant of such condition, the untenantability of which substantially
adversely affects the continued operation in the ordinary course of Tenant's
business, then, provided that such untenantability and Landlord's inability to
cure such condition is not caused by the fault or neglect of Tenant, or Tenant's
agents, employees or contractors, Yearly Rent, Operating Expense Excess and Tax
Excess, shall thereafter be abated in proportion to such untenantability from
the date such notice is received by Landlord until the day such condition is
completely corrected.

                                     -16-
<PAGE>

         (d) Notwithstanding anything to the contrary in this Lease contained,
in the event that the Premises lack any service which Landlord is required to
provide under this Lease thereby rendering the Premises, or any material portion
thereof, untenantable, and (i) if such untenantability continues for ninety (90)
consecutive days, and (ii) if such untenantability is not caused by the fault or
neglect of Tenant or Tenant's agents, employees or contractors, Tenant shall
have the right to terminate this Lease exercisable by giving Landlord a written
termination notice as follows. This Lease shall terminate as of the date ten
(10) days after Landlord's receipt of Tenant's notice, unless Landlord shall
have cured such condition on or before such tenth day.

         8.9 Energy Conservation. Notwithstanding anything to the contrary in
this Article 8 or in this Lease contained, Landlord may institute, and Tenant
shall comply with, such policies, programs and measures as may be necessary,
required, or expedient for the conservation and/or preservation of energy or
energy services to the Premises, so long as the same do not increase any cost or
rent to Tenant or materially interfere with Tenant's business in the Premises,
or as may be necessary or required to comply with applicable codes, rules
regulations or standards.

         8.10 Miscellaneous. All services provided by Landlord to Tenant are
based upon an assumed maximum Premises population of one person per one-hundred
seventy-five (175) square feet of Total Rentable Area, which limit Tenant shall
in no event exceed at any one time.

         8.11 Park Security. Without making any warranty or guaranty as to the
effectiveness of its efforts hereunder, Landlord agrees, at its expense, subject
to the inclusion of such expenses in Operating Costs, to provide security patrol
service in the Park on weeknights (commencing as of 4:00 p.m.) and weekends to
inspect the exterior of the Building and property in the Park.

9.       ESCALATION

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

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

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

         (c) "Tenant's Operating Cost Percentage" and "Tenant's Tax Percentage"
shall be the respective figures as stated in Exhibit 1.

         (d) "Taxes" shall mean the real estate taxes and other taxes, levies
and assessments imposed upon the Park and the land on which it is located and
upon any personal property of Landlord used in the operation thereof, or
Landlord's interest in the

                                     -17-
<PAGE>

Park or such personal property; (provided that if such property is also used in
connection with real estate other than the Park, such taxes, levies, and
assessment shall be equitably allocated to each parcel of real estate) charges,
fees and assessments for transit, housing, police, fire or other governmental
services or purported benefits to the Park; service or user payments in lieu of
taxes; and any and all other taxes, levies, betterments, assessments and charges
arising from the ownership, leasing, operating, use or occupancy of the Park or
based upon rentals derived therefrom, which are or shall be imposed by National,
State, Municipal or other governmental authorities. As of the Execution Date,
"Taxes" shall not include any franchise, rental, income or profit tax, capital
levy or excise, provided, however, that any of the same and any other tax,
excise, fee, levy, charge or assessment, however described, that may in the
future be levied or assessed as a substitute for or an addition to, in whole or
in part, any tax, levy or assessment which would otherwise constitute "Taxes,"
whether or not now customary or in the contemplation of the parties on the
Execution Date of this Lease, shall constitute "Taxes," but only to the extent
calculated as if the Building and the land upon which it stands is the only real
estate owned by Landlord. In addition, "Taxes" shall exclude any increase in
real estate taxes assessed against any leasehold improvements made within
another tenant's Premises to the extent that it is determined from the records
of the Assessing Authority that such increase is based solely upon such
leasehold improvements (e.g., if the Assessing Authority determines Taxes for a
fiscal year based upon an income approach to valuation, in no event shall Taxes
exclude an increase based on change in income of the Park). "Taxes" shall also
include expenses of tax abatement or other proceedings contesting assessments or
levies. The parties acknowledge that Phase II of the Park is assessed as a
separate tax parcel and, therefore, Taxes shall include only Taxes applicable to
Phase II of the Park and shall exclude Taxes assessed against Phase I of the
Park.

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

         (f) "Tax Period" shall be any fiscal/tax period in respect of which
Taxes are due and payable to the appropriate governmental taxing authority, any
portion of which period occurs during the term of this Lease, the first such
Period being the one in which the Term Commencement Date occurs.

         (g) "Operating Costs":

             (1) Definition of Operating Costs. "Operating Costs" shall mean all
         costs incurred and expenditures of whatever nature made by Landlord in
         the operation and management, for repair and replacements, cleaning and

                                     -18-
<PAGE>

         maintenance of the Building and Park, including, without limitation,
         vehicular and pedestrian passageways related to the Building, related
         equipment, facilities and appurtenances, cooling and heating equipment,
         and a portion reasonably allocated by Landlord to the Building of the
         costs and expenditures made by Landlord in the operation and
         management, repair and replacement, cleaning and maintenance of the
         Park. The allocation of costs and expenditures among the various
         buildings in the Park shall be on the basis of the ratio of the Total
         Rentable Area of each building in the Park to the Total Rentable Area
         of the Park, unless such allocation would result in a disproportionate
         charge based upon the relative usage of the service on which such cost
         is based. Initially, the ratio of the Total Rentable Area of the
         Premises to the Total Rentable Area of the Park is the Initial Building
         Proportionate Share. To the extent that a cost included in Operating
         Costs is also allocable to property other than the Park, such cost
         shall be equitably allocated to each parcel of property which benefits
         from such cost. Operating Costs shall include, without limitation,
         those categories of "Specifically Included Operating Costs", as set
         forth below, but shall not include "Excluded Costs", as hereinafter
         defined.

             (2) Definition of Excluded Costs. "Excluded Costs" shall be defined
         as the cost of capital improvements (except as set forth in
         Subparagraph (3) below); depreciation; interest (except as provided in
         Subparagraph (3) below for the amortization of capital improvements);
         principal payments of mortgage and other non-operating debts of
         Landlord; the cost of repairs or other work to the extent Landlord is
         reimbursed by insurance or condemnation proceeds; costs in connection
         with leasing space in the Building, including brokerage commissions;
         lease concessions, including rental abatements and construction
         allowances, granted to specific tenants; costs incurred in connection
         with the sale, financing or refinancing of the Building; fines,
         interest and penalties incurred due to the late payment of Operating
         Costs; organizational expenses associated with the creation and
         operation of the entity which constitutes Landlord; any penalties or
         damages that Landlord pays to Tenant under this Lease or to other
         tenants in the Building under their respective leases; brokerage
         commissions, salaries of executives and owners not directly employed in
         the management/operation of the Building; the cost of work done by
         Landlord for a particular tenant for which Landlord has the right to be
         reimbursed by such tenant; rent under any ground lease; and increases
         in insurance premiums on the Building, the Park or on property located
         therein due to the actions or inactions of another tenant in the
         Building or Park.

             (3) Capital Expenditures.

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

                                     -19-
<PAGE>

             (ii) New Capital Items. If a new capital item is acquired which
         does not replace another capital item which was worn out, has become
         obsolete, etc., and if such new capital item is purchased primarily to
         reduce Operating Costs or otherwise improve the operating efficiency of
         the Building or is required to comply with applicable laws that are
         enacted, or first interpreted to apply to the Building, after the Term
         Commencement Date, then there shall be included in Operating Costs for
         each Operating Year in which and after such capital expenditure is made
         the Annual Charge-Off of such capital expenditure.

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

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

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

             (4) Specifically Included Categories of Operating Costs. Subject to
         the Excluded Costs definition, and as otherwise expressly excluded from
         the definition of Operating Costs pursuant to the provisions of this
         Lease, Operating Costs shall include, but not be limited to, the
         following:

         Taxes (other than real estate taxes): Sales, Federal Social Security,
         Unemployment and Old Age Taxes and contributions and State Unemployment
         taxes and contributions accruing to and paid by the Landlord on account
         of all employees of Landlord and/or Landlord's managing agent, who are
         employed in, about or on account of the Premises, except that taxes
         levied upon the net income

                                      20
<PAGE>

         of the Landlord and taxes withheld from employees, and "Taxes" as
         defined in Article 9.1(d) shall not be included herein.

         Water: All charges and rates connected with water supplied to the
         Premises and/or the Park and related sewer use charges.

         Heat and Air Conditioning: All charges connected with heat and air
         conditioning supplied to the Premises and/or Park.

         Wages: Wages and cost of all employee benefits of all employees of the
         Landlord and/or Landlord's managing agent who are employed in, about or
         on account of the Premises and/or Park provided that (i) wages and
         costs for employees who also work on other properties shall be
         allocated to the Park based upon the proportion of their time spent
         working on the Park and then allocated to the Premises on a square foot
         basis and (ii) wages and costs of employees above the grade of general
         manager shall be excluded from Operating Costs.

         Cleaning: The cost of labor and material for cleaning the Premises,
         surrounding areaways and windows in the Premises and/or Park,
         including, without limitation, the services listed on Exhibit 5.

         Elevator Maintenance: All expenses for or on account of the upkeep and
         maintenance of all elevators in the Premises (if any).

         Electricity: The cost of all electric current for the operation of any
         machine, appliance or device used for the operation of the Premises and
         the Building and/or Park, including the cost of electric current for
         the elevators, lights, air conditioning and heating, but not including
         electric current which is paid for directly to Landlord or to the
         utility by the user/tenant in the Premises and/or Park. (If and so long
         as Tenant is billed directly for its own consumption as determined by
         its separate meter or by submeter, then Operating Costs shall include
         only public area electric current consumption and not any demised
         Premises electric current consumption.) Wherever separate metering is
         unlawful, prohibited by utility company regulation or tariff or is
         otherwise impracticable, relevant consumption figures for the purposes
         of this Article 9 shall be determined by fair and reasonable
         allocations and engineering estimates made by Landlord.

         Insurance, etc.: Fire, casualty, liability and such other insurance as
         may from time to time be reasonably required by lending institutions on
         first-class office buildings in the City or Town wherein the Building
         is located and all other expenses customarily incurred in connection
         with the operation and maintenance of first-class suburban
         office/research and development buildings in the Market Area,
         including, without limitation, market rate rental costs associated with
         the Building's management office.

                                      21
<PAGE>

         Extrapolation to Account for Vacancies. If less than 95% of the Park is
         occupied by tenants throughout any Operating Year for which Operating
         Expense Excess is determined then any Operating Cost which varies based
         upon occupancy (including, without limitation, management fees) for
         such period shall be extrapolated by Landlord on an item by item basis
         to the estimated amount of such Operating Cost which would have been
         incurred if the Park had been at least 95% occupied by tenants
         throughout such Operating Year; and the extrapolated amount shall, for
         the purposes of this Lease, be deemed to be the amount included in
         Operating Costs for such Operating Year. The foregoing extrapolation
         provisions shall apply in determining the Operating Costs in the Base
         Year (if applicable).

         9.2 Tax Excess.

         (a) In General. Commencing as of the Term Commencement Date, and
continuing thereafter throughout the term of this Lease, if in any Tax Period
the Taxes exceed the Tax Base, Tenant shall pay to Landlord Tenant's Tax
Percentage of such excess, such amount being hereinafter referred to as "Tax
Excess." Tax Excess shall be due within thirty (30) days of Tenant's receipt of
Landlord's bill therefor. In implementation and not in limitation of the
foregoing, Tenant shall remit to Landlord pro rata monthly installments on
account of projected Tax Excess, calculated by Landlord on the basis of the most
recent Tax data available. If the total of such monthly remittances on account
of any Tax Period is greater than the actual Tax Excess for such Tax Period,
Tenant may credit the difference against the next installment of rental or other
charges due to Landlord hereunder, except that if such difference is determined
after the end of the term of this Lease, Landlord shall refund such difference
to Tenant to the extent that such difference exceeds any amounts then due from
Tenant to Landlord. If the total of such remittances is less than the actual Tax
Excess for such Tax Period, Tenant shall pay the difference to Landlord within
thirty (30) days of Tenant's receipt of the bill.

         (b) Effect of Abatements. Appropriate credit against Tax Excess shall
be given for any refund obtained by reason of a reduction in any Taxes by the
Assessors or the administrative, judicial or other governmental agency
responsible therefor. The original computations, as well as reimbursement or
payments of additional charges, if any, or allowances, if any, under the
provisions of this Article 9.2 shall be based on the original assessed
valuations with adjustments to be made at a later date when the tax refund, if
any, shall be paid to Landlord by the taxing authorities. Expenditures for legal
fees and for other similar or dissimilar expenses incurred in obtaining the tax
refund may be charged against the tax refund before the adjustments are made for
the Tax Period.

         9.3 Operating Expense Excess.

         (a) In General. Commencing as of the Term Commencement Date, and
continuing thereafter throughout the term of the Lease, if the Operating Costs
in any Operating Year exceed the Operating Costs in the Base Year, Tenant shall
pay to Landlord Tenant's Operating Cost Percentage of such excess, such amount
being

                                      22
<PAGE>

hereinafter referred to as "Operating Expense Excess." Operating Expense Excess
shall be due within thirty (30) days of the Tenant's receipt of the Landlord's
bill therefor. In implementation and not in limitation of the foregoing, Tenant
shall remit to Landlord pro rata monthly installments on account of projected
Operating Expense Excess, calculated by Landlord on the basis of the most recent
Operating Costs data or budget available. Landlord shall, within one hundred
twenty (120) days after the end of each Operating Year, deliver to Tenant a
reasonably detailed statement ("Year End Statement") of the actual amount of
Operating Costs for such Operating Year. If the total of such monthly
remittances on account of any Operating Year is greater than the actual
Operating Expense Excess for such Operating Year, Tenant may credit the
difference against the next installment of rent or other charges due to Landlord
hereunder, except that if such difference is determined after the end of the
term of this Lease, Landlord shall refund such difference to Tenant to the
extent that such difference exceeds any amounts then due from Tenant to
Landlord. If the total of such remittances is less than actual Operating Expense
Excess for such Operating Year, Tenant shall pay the difference to Landlord
within thirty (30) days of Tenant's receipt of Landlord's bill therefor.

         (b) Tenant's Audit Rights. Subject to the provisions of this paragraph,
Tenant shall have the right, at Tenant's cost and expense, to examine all
documentation and calculations prepared in the determination of Operating
Expense Excess:

         (1) Such documentation and calculation shall be made available to
         Tenant at the offices where Landlord keeps such records during normal
         business hours within a reasonable time after Landlord receives a
         written request from Tenant to make such examination.

         (2) Tenant shall have the right to make such examination no more than
         once in respect of any period in which Landlord has given Tenant a Year
         End Statement.

         (3) Any request for examination in respect of any Operating Year may be
         made no more than one hundred eighty (180) days after Landlord has
         given Tenant a Year End Statement for such Operating Year.

         (4) Such examination may be made first by Tenant and any employees of
         Tenant, and then, at Tenant's election, by an independent certified
         public accounting firm, provided that in no event shall the
         compensation payable by Tenant to such firm be on the basis of a
         contingent fee.

         (5) As a condition to performing any such examination, Tenant and its
         examiners shall be required to execute and deliver to Landlord an
         agreement, in form mutually acceptable to Landlord and Tenant, agreeing
         to keep confidential any information which it discovers about Landlord
         or the Building in connection with such examination, except in court or
         as may be required by law.

                                      23
<PAGE>

         9.4 Part Years. If the Term Commencement Date or if the Termination
Date occurs in the middle of an Operating Year or Tax Period, Tenant shall be
liable for only that portion of the Operating Expense or Tax Excess, as the case
may be, in respect of such Operating Year or Tax Period represented by a
fraction the numerator of which is the number of days of the herein term
(commencing as of the Term Commencement Date) which falls within the Operating
Year or Tax Period and the denominator of which is three hundred sixty-five
(365), or the number of days in said Tax Period, as the case may be.

         9.5 Effect of Taking. In the event of any taking of a portion of the
Park, the Building or the land upon which it stands under circumstances whereby
this Lease shall not terminate under the provisions of Article 20 then, for the
purposes of determining Tax Excess, there shall be substituted for the Tax Base
originally provided for herein a fraction of such Tax Base, the numerator of
which fraction shall be the Taxes for the first Tax Period subsequent to the
condemnation or taking which takes into account such condemnation or taking, and
the denominator of which shall be the Taxes for the last Tax Period prior to the
condemnation or taking, which did not take into account such condemnation or
taking. Tenant's Tax Percentage shall be adjusted appropriately to reflect the
proportion of the Premises and/or the Building remaining after such taking.

         9.6 Adjustment of Operating Costs and Taxes based upon Occupancy. If
less than ninety-five (95%) percent of the rentable area of the Building shall
have been occupied by tenants at any time during any Operating Year or Tax
Period, then, at Landlord's election, Operating Costs or Taxes, or both, for
such Operating Year or Tax Period, as the case may be, shall be adjusted to
equal the amount which Landlord in good faith determines is the amount Operating
Costs or Taxes, or both, would have been for such period had occupancy been
ninety-five (95%) percent throughout such period.

         9.7 Survival of Obligations. Any obligations under this Article 9 which
shall not have been paid at the expiration or sooner termination of the term of
this Lease shall survive such expiration and shall be paid when and as the
amount of same shall be determined to be due.

10.      CHANGES OR ALTERATIONS BY LANDLORD

         Landlord reserves the right, exercisable by itself or its nominee, at
any time and from time to time without the same constituting an actual or
constructive eviction and without incurring any liability to Tenant therefor or
otherwise affecting Tenant's obligations under this Lease, to make such changes,
alterations, additions, improvements, repairs or replacements in or to the
Premises, the Building and/or the Park and the fixtures and equipment thereof,
as well as in or to the street entrances, halls, passages, elevators,
escalators, parking areas, tunnels, and stairways thereof, as it may deem
necessary or desirable, and to change the arrangement and/or location of
entrances or passageways, doors and doorways, and corridors, elevators, stairs,
toilets, or other public parts of the Building and/or the Park, provided,
however, that there be no unreasonable obstruction of the right of access to, or
material interference with the use and enjoyment

                                      24
<PAGE>

of, the Premises or Tenant's appurtenant rights. Notwithstanding the foregoing:
(i) Landlord's rights under this Article 10 are subject to Article 2.4, and (ii)
unless required by law, Landlord shall make any alteration, addition, or
improvement of the Premises only if the same are performed in accordance with
the Landlord access procedures set forth in Article 2.4, and if the same shall
not materially interfere with the use and enjoyment by Tenant of the Premises or
Tenant's appurtenant rights. Nothing contained in this Article 10 shall be
deemed to relieve Tenant of any duty, obligation or liability of Tenant under
this Lease with respect to making any repair, replacement or improvement or
complying with any law, order or requirement of any governmental or other
authority. Landlord reserves the right, upon at least 30 days' prior written
notice to Tenant, to adopt and at any time and from time to time to change the
name of the Building and/or the Park. Neither this Lease nor any use by Tenant
shall give Tenant any right or easement for the use of any door or any passage
or any concourse connecting with any other building or to any public
convenience, and the use of such doors, passages and concourses and of such
conveniences may be regulated or discontinued at any time and from time to time
by Landlord without notice to Tenant and without affecting the obligation of
Tenant hereunder or incurring any liability to Tenant therefor, provided,
however, that there be no unreasonable obstruction of the right of access to, or
unreasonable interference with the use of the Premises by Tenant. If at any time
any windows of the Premises are temporarily (i.e. not in excess of five days)
closed or darkened for any reason whatsoever relating to any maintenance or
repair work, but Tenant shall not otherwise be prevented from occupying or using
the Premises for the uses set forth herein, Landlord shall not be liable for any
damage Tenant may sustain thereby and Tenant shall not be entitled to any
compensation therefor nor abatements of rent nor shall the same release Tenant
from its obligations hereunder nor constitute an eviction.

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

         All fixtures, equipment, improvements and appurtenances attached to or
built into the Premises prior to or during the term, whether by Landlord at its
expense or at the expense of Tenant (either or both) or by Tenant shall be and
remain part of the Premises and shall not be removed by Tenant during or at the
end of the term unless Landlord otherwise elects to require Tenant to remove
such fixtures, equipment, improvements and appurtenances, subject to the
provisions of Articles 12 and/or 22 of the Lease. All electric, plumbing,
heating and sprinkling systems, fixtures and outlets, vaults, paneling, molding,
shelving, radiator enclosures, cork, rubber, linoleum and composition floors,
ventilating, silencing, air conditioning and cooling equipment, shall be deemed
to be included in such fixtures, equipment, improvements and appurtenances,
whether or not attached to or built into the Premises. Where not built into the
Premises, all removable electric fixtures, carpets, drinking or tap water
facilities, furniture, or trade fixtures or business equipment or Tenant's
inventory or stock in trade shall not be deemed to be included in such fixtures,
equipment, improvements and appurtenances and may be, and upon the request of
Landlord will be, removed by Tenant at the expiration or prior termination of
this term of the Lease, upon the condition that such removal shall not

                                      25
<PAGE>

materially damage the Premises or the Building and that the cost of repairing
any damage to the Premises or the Building arising from installation or such
removal shall be paid by Tenant.

12.      ALTERATIONS AND IMPROVEMENTS BY TENANT

         (a) Tenant shall make no alterations, decorations, installations,
removals, additions or improvements (collectively, "Alterations") in or to the
Premises without Landlord's prior written consent and then only those made by
contractors or mechanics approved by Landlord. No installations or work shall be
undertaken or begun by Tenant until: (i) Landlord has approved written plans and
specifications and a time schedule for such work; (ii) Tenant has made provision
for either written waivers of liens from all contractors, laborers and suppliers
of materials for such installations or work, the filing of lien bonds on behalf
of such contractors, laborers and suppliers, or other appropriate protective
measures approved by Landlord; and (iii) Tenant has procured appropriate surety
payment and performance bonds. No amendments or additions to such plans and
specifications shall be made without the prior written consent of Landlord.

         (b) Landlord's consent and approval required under this Article 12
shall not be unreasonably withheld. Landlord's approval is solely given for the
benefit of Landlord and neither Tenant nor any third party shall have the right
to rely upon Landlord's approval of Tenant's plans for any purpose whatsoever,
except for compliance with Article 12(a). Without limiting the foregoing, Tenant
shall be responsible for all elements of the design of Tenant's plans
(including, without limitation, compliance with law, functionality of design,
the structural integrity of the design, the configuration of the Premises and
the placement of Tenant's furniture, appliances and equipment), and Landlord's
approval of Tenant's plans shall in no event relieve Tenant of the
responsibility for such design. Landlord shall have no liability or
responsibility for any claim, injury or damage alleged to have been caused by
the particular materials, whether building standard or non-building standard,
appliances or equipment selected by Tenant in connection with any work performed
by or on behalf of Tenant in the Premises including, without limitation,
furniture, carpeting, copiers, laser printers, computers and refrigerators.

         (c) Notwithstanding anything to the contrary herein contained,
Landlord's consent shall not be required for any Alteration that satisfies all
of the following criteria: (1) is of a cosmetic nature such as painting,
wallpapering, hanging pictures and installing carpeting; (2) is not visible from
the exterior of the Premises or Building; (3) will not affect the systems or
structure of the Building; and (4) does not require work to be performed behind
the walls or above the ceiling of the Premises.

         (d) Any such Alterations shall be done at Tenant's sole expense and at
such times and in such manner as Landlord may from time to time reasonably
designate. If Tenant shall make any Alterations, then Landlord may elect to
require the Tenant at the expiration or sooner termination of the term of this
Lease to restore the Premises to substantially the same condition as existed at
the Term Commencement Date. If so

                                      26
<PAGE>

requested by Tenant in writing at the time that Tenant requests Landlord's
approval, or gives Landlord written notice, as the case may be, of an
Alteration, Landlord shall, within ten (10) business days of its receipt of such
request, make its election as to whether Tenant shall be required to remove such
Alteration. In any event, Tenant shall be required to remove its data lines and
cable from the Premises at the end of the term of the Lease.

         (e) Tenant shall pay, as an additional charge, the entire increase in
real estate taxes on the Building which shall, at any time prior to or after the
Term Commencement Date, result from or be attributable to any alteration,
addition or improvement to the Premises made by or for the account of Tenant in
excess of the value of Landlord's Work.

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

         Whenever Tenant shall make any alterations, decorations, installations,
removals, additions or improvements in or to the Premises--whether such work be
done prior to or after the Term Commencement Date--Tenant will strictly observe
the following covenants and agreements:

         (a) Tenant agrees that it will not, either directly or indirectly, use
any contractors and/or materials if their use will create any difficulty,
whether in the nature of a labor dispute or otherwise, with other contractors
and/or labor engaged by Tenant or Landlord or others in the construction,
maintenance and/or operation of the Building or any part thereof.

         (b) In no event shall any material or equipment be incorporated in or
added to the Premises, so as to become a fixture or otherwise a part of the
Building, in connection with any such alteration, decoration, installation,
addition or improvement which is subject to any lien, charge, mortgage or other
encumbrance of any kind whatsoever or is subject to any security interest or any
form of title retention agreement. Any mechanic's lien filed against the
Premises or the Building for work claimed to have been done for, or materials
claimed to have been furnished to, Tenant shall be discharged by Tenant within
ten (10) days thereafter, at Tenant's expense by filing the bond required by law
or otherwise. If Tenant fails so to discharge any lien, Landlord may do so at
Tenant's expense and Tenant shall reimburse Landlord for any expense or cost
incurred by Landlord in so doing within fifteen (15) days after rendition of a
bill therefor. Notwithstanding the foregoing, Tenant shall have the right to
grant security interests and/or to lease its business equipment and personal
property in the premises, provided that such lessor or secured party agrees:

                  1.       That it will repair any damage to the Building or the
                           Premises caused by the installation or removal of any
                           such equipment or personal property;

                                      27
<PAGE>

                  2.       That it will give Landlord not less than five (5)
                           days advance written notice prior to making any entry
                           into the Premises;

                  3.       That it will not hold any auction or foreclosure sale
                           on the Premises; and

                  4.       That it will have the right to remove such equipment
                           or property only during the term of this Lease.

         (c) All installations or work done by Tenant shall be at its own
expense and shall at all times comply with (i) laws, rules, orders and
regulations of governmental authorities having jurisdiction thereof; (ii)
orders, rules and regulations of any Board of Fire Underwriters, or any other
body hereafter constituted exercising similar functions, and governing insurance
rating bureaus; (iii) Rules and Regulations of Landlord; and (iv) plans and
specifications prepared by and at the expense of Tenant (except Landlord shall
pay for Tenant's Final Plans as provided in Article 4.4(b)) theretofore
submitted to and approved by Landlord.

         (d) Tenant shall procure all necessary permits before undertaking any
work in the Premises; do all of such work in a good and workmanlike manner,
employing materials of good quality and complying with all governmental
requirements; and defend, save harmless, exonerate and indemnify Landlord from
all injury, loss or damage to any person or property occasioned by such work.
Tenant shall cause contractors employed by Tenant to carry Worker's Compensation
Insurance in accordance with statutory requirements, Automobile Liability
Insurance and, naming Landlord as an additional insured, Commercial General
Liability Insurance covering such contractors on or about the Premises in the
amounts stated in Article 15 hereof or in such other reasonable amounts as
Landlord shall require and to submit certificates evidencing such coverage to
Landlord prior to the commencement of such work.

14.      REPAIRS BY TENANT--FLOOR LOAD

         14.1 Repairs by Tenant. Tenant shall keep all and singular the Premises
neat and clean including, as necessary, periodic rug shampoo and waxing of tiled
floors and cleaning of blinds and drapes (provided that nothing herein shall
require Tenant to perform any services which Landlord is required to perform
under Exhibit 5) and in such repair, order and condition as the same are in on
the Term Commencement Date or may be put in during the term hereof, reasonable
use and wear thereof and damage by fire or by other casualty excepted. Tenant
shall make, as and when needed as a result of neglect by Tenant or Tenant's
servants, employees, agents, contractors, invitees, or licensees or otherwise,
all repairs in and about the Premises necessary to preserve them in such repair,
order and condition, which repairs shall be in quality and class equal to the
original work. Landlord may elect, at the expense of Tenant, to make any such
repairs or to repair any damage or injury to the Building or the Premises caused
by the neglect of Tenant or

                                      28
<PAGE>

Tenant's servants, employees, agents, contractors, or licensees if Tenant fails
to make such repairs within thirty (30) day after written notice from Landlord
(except that no notice shall be required in an emergency).

         14.2 Floor Load--Heavy Machinery. Tenant shall not place a load upon
any floor of the Premises exceeding the floor load per square foot of area which
such floor was designed to carry and which is allowed by law. Landlord reserves
the right to prescribe the weight and position of all business machines and
mechanical equipment, including safes, which shall be placed so as to distribute
the weight. Business machines and mechanical equipment shall be placed and
maintained by Tenant at Tenant's expense in settings sufficient in Landlord's
judgment to absorb and prevent vibration, noise and annoyance. Tenant shall not
move any safe, heavy machinery, heavy equipment, freight, bulky matter, or
fixtures into or out of the Building without Landlord's prior written consent.
If such safe, machinery, equipment, freight, bulky matter or fixtures requires
special handling, Tenant agrees to employ only persons holding a Master Rigger's
License to do said work, and that all work in connection therewith shall comply
with applicable laws and regulations. Any such moving shall be at the sole risk
and hazard of Tenant and Tenant will defend, indemnify and save Landlord
harmless against and from any liability, loss, injury, claim or suit resulting
from such moving. Proper placement of all such business machines, etc., in the
Premises shall be Tenant's responsibility. Landlord agrees that it shall
exercise its rights under this Article 14.2 on a reasonable basis.

15.      INSURANCE, INDEMNIFICATION, EXONERATION AND EXCULPATION

         15.1 General Liability Insurance. Tenant shall procure, and keep in
force and pay for Commercial General Liability Insurance insuring Tenant on an
occurrence basis against all claims and demands for bodily injury liability
(including, without limitation, bodily injury, sickness, disease, and death) or
damage to property which may be claimed to have occurred from and after the time
Tenant and/or its contractors enter the Premises in accordance with Article 4 of
this Lease, of not less than Two Million ($2,000,000) Dollars in the event of
bodily injury to any number of persons or damage to property, arising out of any
one occurrence, and from time to time thereafter shall be not less than such
higher amounts, if procurable, as may be reasonably required by Landlord and are
customarily carried by responsible similar tenants in the City or Town wherein
the Building is located. Landlord agrees it shall exercise its right to increase
Tenant's insurance limits no more often than one time every three years.

         15.2 Certificates of Insurance. Such insurance may be obtained under a
blanket insurance policy, and shall be effected with insurers with a Best rating
of at least XI, A-, authorized to do business in the Commonwealth of
Massachusetts under valid and enforceable policies wherein Tenant names Landlord
and Landlord's managing agent as additional insureds. Such insurance shall
provide that it shall not be canceled or modified without at least thirty (30)
days' prior written notice to each insured named therein. On or before the time
Tenant and/or its contractors enter the Premises in accordance with

                                      29
<PAGE>

Articles 4 and 14 of this Lease and thereafter not less than fifteen (15) days
prior to the expiration date of each expiring policy, original copies of the
policies provided for in Article 15.1 issued by the respective insurers, or
certificates of such policies setting forth in full the provisions thereof and
issued by such insurers together with evidence satisfactory to Landlord of the
payment of all premiums for such policies, shall be delivered by Tenant to
Landlord and certificates as aforesaid of such policies shall upon request of
Landlord, be delivered by Tenant to the holder of any mortgage affecting the
Premises.

         15.3  Tenant Indemnity of Landlord. Subject to Article 19, Tenant will
save Landlord, its agents and employees, harmless and will exonerate, defend and
indemnify Landlord, its agents and employees, from and against any and all
claims, liabilities or penalties asserted by or on behalf of any person, firm,
corporation or public authority arising:

         (a)   On account of or based upon any injury to person, or loss of or
damage to property, sustained or occurring on the Premises on account of or
based upon the act, omission, fault, negligence or misconduct of any person
whomsoever (except to the extent caused by Landlord, its agents, contractors or
employees);

         (b)   On account of or based upon any injury to person, or loss of or
damage to property, sustained or occurring elsewhere (other than on the
Premises) in the Park (and, in particular, without limiting the generality of
the foregoing, on or about the elevators, stairways, public corridors,
sidewalks, concourses, arcades, malls, galleries, vehicular tunnels, approaches,
areaways, roof, or other appurtenances and facilities used in connection with
the Park, Building or Premises) to the extent caused by the negligence or
willful misconduct of Tenant or anyone claiming by, through, or under Tenant, or
their respective agents, employees or contractors; and

         (c)   Tenant's obligations under this Article 15.3 shall be insured
either under the Commercial General Liability Insurance required under Article
15.1, above, or by a contractual insurance rider or other coverage; and
certificates of insurance in respect thereof shall be provided by Tenant to
Landlord upon request.

         15.3A Landlord Indemnity of Tenant. Except to the extent caused by the
negligence or willful misconduct of Tenant, its agents, contractors or
employees, Landlord shall indemnify, defend and hold Tenant, its agents,
contractors and employees harmless against and from all liabilities,
obligations, damages, penalties, claims, actions, costs, charges and expenses,
including, without limitation, reasonable attorneys' fees and other professional
fees (if and to the extent permitted by Law), which may be imposed upon,
incurred by or asserted against Tenant, its agents, contractors or employees and
arising out of or in connection with the acts or omissions (including violations
of law) of Landlord, its agents, contractors or employees.

         15.4  Property of Tenant. In addition to and not in limitation of the
foregoing, Tenant covenants and agrees that, to the maximum extent permitted by
law, all

                                      30
<PAGE>

merchandise, furniture, fixtures and property of every kind, nature and
description related or arising out of Tenant's leasehold estate hereunder, which
may be in or upon the Premises or Building, in the public corridors, or on the
sidewalks, areaways and approaches adjacent thereto, shall be at the sole risk
and hazard of Tenant, and that if the whole or any part thereof shall be
damaged, destroyed, stolen or removed from any cause or reason whatsoever no
part of said damage or loss shall be charged to, or borne by, Landlord; unless,
subject to Article 19 hereof, such damage or loss is due to the negligence or
willful misconduct of Landlord or Landlord's agents, employees, or contractors,
in which case Landlord shall bear loss or damage only to "ordinary office
property" (as hereinafter defined). For the purpose of this Article 15.4,
"ordinary office property" shall mean merchandise, furniture, and other tangible
personal property of the kind and quantity which may customarily be expected to
be found within comparable business offices in the greater Boston area, and
excluding any unusually valuable or exotic property, works of art, and the like.

         15.5  Bursting of Pipes, etc. Landlord shall not be liable for any
injury or damage to persons or property resulting from fire, explosion, falling
plaster, steam, gas, electricity, electrical or electronic emanations or
disturbance, water, rain or snow or leaks from any part of the Building or from
the pipes, appliances, equipment or plumbing works or from the roof, street or
sub-surface or from any other place or caused by dampness, vandalism, malicious
mischief or by any other cause of whatever nature, unless caused by or due to
the negligence or willful misconduct of Landlord, its agents, servants or
employees, or the breach by Landlord of its maintenance and repair obligations
under this Lease, and then, where notice and an opportunity to cure are
appropriate (i.e., where Tenant knows of such condition sufficiently in advance
of the occurrence of any such injury or damage resulting therefrom as would have
enabled Landlord to prevent such damage or loss had Tenant notified Landlord of
such condition) only after (i) notice to Landlord of the condition claimed to
constitute negligence or breach and (ii) the expiration of a reasonable time
after such notice has been received by Landlord without Landlord having taken
all reasonable and practicable means to cure or correct such condition; and
pending such cure or correction by Landlord, Tenant shall take all reasonably
prudent temporary measures and safeguards to prevent any injury, loss or damage
to persons or property. Neither Landlord nor its agents shall be liable for any
such damage caused by other tenants or persons in the Building (other than
Landlord's agents, employees or contractors) or caused by operations in
construction of any public, or quasi-public work; nor shall Landlord be liable
for any latent defect in the Premises or in the Building, provided that the
foregoing shall not relieve Landlord from any obligation which it has to perform
maintenance or repairs in accordance with the Lease or relieve Landlord of any
obligation which it has in connection with Landlord's Work to the extent that
Tenant has complied with the notice requirements of Article 4.8.

         15.6 Repairs and Alterations--No Diminution of Rental Value.

         (a) Except as otherwise provided in paragraphs (b) and (c) of this
Article 15.6 and as provided in Article 18, there shall be no allowance to
Tenant for diminution of rental value and no liability on the part of Landlord
by reason of inconvenience,

                                     -31-
<PAGE>

annoyance or injury to Tenant arising from any repairs, alterations, additions,
replacements or improvements made by Landlord, Tenant or others in or to any
portion of the Park, Building or Premises or any property adjoining the Park, or
in or to fixtures, appurtenances, or equipment thereof, or for failure of
Landlord or others to make any repairs, alterations, additions or improvements
in or to any portion of the Park, Building, or of the Premises, or in or to the
fixtures, appurtenances or equipment thereof.

         (b) Notwithstanding anything to the contrary in this Lease contained,
if due to any such repairs, alterations, replacements, or improvements made by
Landlord or if due to Landlord's failure to make any repairs, alterations, or
improvements required to be made by Landlord, or if due to the breach by
Landlord of any of its obligations under the Lease, any portion of the Premises
becomes untenantable for a period of three (3) consecutive days after Landlord's
receipt of written notice from Tenant of such condition, the untenantability of
which would substantially adversely affect the continued operation in the
ordinary course of Tenant's business, then, provided that such untenantability
and Landlord's inability to cure such condition is not caused by the fault or
neglect of Tenant or Tenant's agents, employees or contractors or caused beyond
Landlord's reasonable control (excluding financial inability to perform
obligations), Yearly Rent, Operating Expense Excess and Tax Excess shall be
abated in proportion to such untenantability from the date such notice is
received by Landlord until the day such condition is completely corrected.

         (c) Notwithstanding anything to the contrary in this Lease contained,
if due to any such repairs, alterations, replacements, or improvements made by
Landlord or if due to Landlord's failure to make any repairs, alterations, or
improvements required to be made by Landlord, or if due to the breach by
Landlord of any of its obligations under the Lease, any portion of the Premises
becomes untenantable for a period of ten (10) consecutive days after Landlord's
receipt of written notice from Tenant of such condition, the untenantability of
which would substantially adversely affect the continued operation in the
ordinary course of Tenant's business, then, provided that such untenantability
and Landlord's inability to cure such condition is not caused by the fault or
neglect of Tenant or Tenant's agents, employees or contractors, Yearly Rent,
Operating Expense Excess and Tax Excess shall be abated in proportion to such
untenantability from the date such notice is received Landlord until the day
such condition is completely corrected.

         (d) Notwithstanding anything to the contrary in the Lease contained, if
due to any such repairs, alterations, replacements, or improvements made by
Landlord or if due to Landlord's failure to make any repairs, alterations, or
improvements required to be made by Landlord, or if due to the breach by
Landlord of any of its obligations under the Lease, any portion of the Premises
becomes untenantable after Landlord's receipt of written notice from Tenant of
such condition, the untenantability of which materially adversely affects the
continued operation in the ordinary course of Tenant's business, and (i) if such
untenantability continues for ninety (90) consecutive days, and (ii) such
untenantability and Landlord inability to cure such conditions is not caused by
the fault or neglect of Tenant, or Tenant's agents, employees, or contractors,
then Tenant shall have the right to terminate this Lease exercisable by giving
Landlord a written termination

                                     -32-
<PAGE>

notice as follows. This Lease shall terminate as of the date ten (10) days after
Landlord's receipt of Tenant's notice, unless Landlord shall have cured such
condition on or before such tenth day.

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

         15.7 Landlord Indemnity of Tenant. Landlord, subject to the limitations
on Landlord's liability contained elsewhere in this Lease, agrees to hold Tenant
harmless and to defend, exonerate and indemnify Tenant from and against any and
all claims, liabilities, or penalties asserted by or on behalf of any third
party (i.e. any person, firm, corporation or public authority) for damage to
property or injuries to persons on account of or based upon any injury to
persons, or loss of or damage to property, sustained or occurring in the Park to
the extent arising from the negligence, or willful misconduct of Landlord or
Landlord's agents, employees or contractors. The provisions of this Article 15.7
shall survive any termination of the Lease.

16.      ASSIGNMENT, MORTGAGING AND SUBLETTING

         16.1  General Prohibition Against Transfers. Tenant shall not assign,
sublease, transfer or encumber this Lease or any interest therein or grant any
license, concession or other right of occupancy of the Premises or any portion
thereof or otherwise permit the use of the Premises or any portion thereof by
any party other than Tenant (any of which events is hereinafter called a
"Transfer") without the prior written consent of Landlord, which consent shall
not be unreasonably withheld with respect to any proposed assignment or
subletting. Landlord's consent shall not be considered unreasonably withheld if:
(1) the proposed transferee's financial responsibility does not meet the same
criteria Landlord uses to select Building tenants; (2) the proposed transferee's
business is not suitable for the Building considering the business of the other
tenants and the Building's prestige or would result in a violation of an
exclusive right granted to another tenant in the Building; (3) the proposed use
is different than the Permitted Use; (4) the proposed transferee is a government
agency or occupant of the Building; (5) Tenant is in default after the
expiration of the notice and cure periods in this Lease; or (6) any portion of
the Building or Premises would become subject to additional or different
governmental laws or regulations as a consequence of the proposed Transfer
and/or the proposed transferee's use and occupancy of the Premises. Tenant
acknowledges that the foregoing is not intended to be an exclusive list of the
reasons for which Landlord may reasonably withhold its consent to a proposed
Transfer. Any attempted Transfer in violation of the terms of this Article
shall, at Landlord's option, be void. Consent by Landlord to one or more
Transfers shall not operate as a waiver of Landlord's rights as to any
subsequent Transfers. In addition, Tenant shall not, without Landlord's consent,
publicly advertise the proposed rental rate for any Transfer. Notwithstanding
anything to the contrary contained herein or in Article 16.4., Tenant may assign
its entire interest under this Lease or sublet the Premises to a wholly owned
corporation, partnership or other legal entity or affiliate, subsidiary or
parent of Tenant or

                                     -33-
<PAGE>

to any successor to Tenant by purchase, merger, consolidation or reorganization
(hereinafter, collectively, referred to as "Permitted Transfer") without the
consent of Landlord, provided: (i) Tenant is not in default under this Lease;
(ii) if such proposed transferee is a successor to Tenant by purchase, merger,
consolidation or reorganization, the continuing or surviving entity shall own
all or substantially all of the assets of Tenant and shall have a net worth
which is at least equal to Tenant's net worth at the date of the Transfer; (iii)
such proposed transferee operates the business in the Premises for the permitted
use and no other purpose; and (iv) in no event shall any Transfer release or
relieve Tenant from any of its obligations under this Lease. Tenant shall give
Landlord written notice at least thirty (30) days prior to the effective date of
such Permitted Transfer. As used herein: (a) "parent" shall mean a company which
owns a majority of Tenant's voting equity; (b) "subsidiary" shall mean a entity
wholly owned by Tenant or at least fifty-one percent (51%) of whose voting
equity is owned by Tenant; and (c) "affiliate" shall mean an entity controlled,
controlling or under common control with Tenant. Notwithstanding the foregoing,
sale of the shares of equity of any affiliate or subsidiary to which this Lease
has been assigned or transferred other than to another parent, subsidiary or
affiliate of the original Tenant named hereunder shall be deemed to be an
assignment requiring the consent of Landlord hereunder, except to the extent
otherwise provided in Article 16.4 of the Lease.

         16.2  Landlord's Rights upon Tenant's Request for Sublet Consent. If
Tenant requests Landlord's consent to a Transfer, Tenant, together with such
request for consent, shall provide Landlord with the name of the proposed
transferee and the nature of the business of the proposed transferee, the term,
use, rental rate and all other material terms and conditions of the proposed
Transfer, including, without limitation, a copy of the proposed assignment,
sublease or other contractual documents and evidence satisfactory to Landlord
that the proposed transferee is financially responsible. Notwithstanding
Landlord's agreement to act reasonably under Article 16.1 above, Landlord may,
within thirty (30) days after its receipt of all information and documentation
required herein, either, (1) consent to or reasonably refuse to consent to such
Transfer in writing; or (2) terminate this Lease in connection with a proposed
assignment or with respect to the portion of the Premises proposed to be sublet
upon thirty (30) days' notice, in which event such termination shall not be
considered to be a default by Tenant and Landlord shall not be entitled to any
damages from Tenant on account of any termination under this Article 16.2. In
the event Landlord consents to any such Transfer, the Transfer and consent
thereto shall be in a form approved by Landlord, and Tenant shall pay Landlord a
review fee of Seven Hundred Fifty Dollars ($750.00), provided if Landlord's
actual reasonable costs and expenses (including reasonable attorneys' fees)
exceed $750.00, Tenant shall reimburse Landlord for its actual reasonable costs
and expenses in lieu of a fixed review fee.

         16.3  Transfer Consideration. Fifty (50%) percent of all cash or other
proceeds (the "Transfer Consideration") of any Transfer of Tenant's interest in
this Lease and/or the Premises, whether consented to by Landlord or not, shall
be paid to Landlord and Tenant hereby assigns all rights it might have or ever
acquire in any such proceeds to Landlord. In addition to the Rent hereunder,
Tenant hereby covenants and agrees to pay

                                     -34-
<PAGE>

to Landlord fifty (50%) percent of all rent and other consideration which it
receives which is in excess of the Rent payable hereunder within ten (10) days
following receipt thereof by Tenant. Tenant may, prior to paying Landlord any
Transfer Consideration, deduct from the excess all reasonable and customary
expenses directly incurred by Tenant attributable to the Transfer including
brokerage fees, legal fees and construction costs. In addition to any other
rights Landlord may have, Landlord shall have the right to contact any
transferee and require that all payments made pursuant to the Transfer shall be
made directly to Landlord.

         16.4  Transfer of Beneficial Interests in Tenant. If Tenant is a
corporation, limited liability company or similar entity, and if at any time
during the Lease Term the entity or entities who own the voting shares at the
time of the execution of this Lease cease for any reason (including but not
limited to merger, consolidation or other reorganization involving another
corporation) to own a majority of such shares, or if Tenant is a partnership and
if at any time during the Lease Term the general partner or partners who own the
general partnership interests in the partnership at the time of the execution of
this Lease, cease for any reason to own a majority of such interests (except as
the result of transfers by gift, bequest or inheritance to or for the benefit of
members of the immediate family of such original shareholder[s] or partner[s]),
such an event shall be deemed to be a Transfer. The preceding sentence shall not
apply whenever Tenant is a corporation, the outstanding stock of which is listed
on a recognized security exchange, or if at least eighty percent (80%) of its
voting stock is owned by another corporation, the voting stock of which is so
listed.

         16.5  Effect of Landlord's Consent to Transfer. Any Transfer consented
to by Landlord in accordance with this Article 16 shall be only for the
Permitted Use and for no other purpose. In no event shall any Transfer release
or relieve Tenant from any obligations under this Lease.

17.      MISCELLANEOUS COVENANTS

         Tenant covenants and agrees as follows:

         17.1  Rules and Regulations. Tenant will faithfully observe and comply
with the Rules and Regulations (if any) annexed hereto, and such other and
further reasonable Rules and Regulations as Landlord hereafter at any time or
from time to time may make and may communicate in writing to Tenant, which in
the reasonable judgment of Landlord shall be necessary for the reputation,
safety, care or appearance of the Building and/or the Park, or the preservation
of good order therein, or the operation or maintenance of the Building and/or
the Park, or the equipment thereof, or the comfort of tenants or others in the
Park, provided, however, that in the case of any conflict between the provisions
of this Lease and any such Rules and Regulations, the provisions of this Lease
shall control, and provided further that nothing contained in this Lease shall
be construed to impose upon Landlord any duty or obligation to enforce the Rules
and Regulations or the terms, covenants or conditions in any other lease as
against any other tenant and Landlord shall not be liable to Tenant for
violation of the same by any other

                                     -35-
<PAGE>

tenant, its servants, employees, agents, contractors, visitors, invitees or
licensees. In no event shall any rules and regulations discriminate against
Tenant in enforcement or effect (i.e., the Rules and Regulations shall be the
same for all tenants of the Park with similar uses). Notwithstanding anything to
the contrary in this Lease contained, Landlord agrees that it will not enforce
said Rules and Regulations against Tenant in a discriminatory or arbitrary
manner.

         17.2  Access to Premises--Shoring. Subject to Article 2.4 and 10,
Tenant shall: (i) permit Landlord to erect, use and maintain pipes, ducts and
conduits in and through the Premises, provided the same do not materially reduce
the floor area, materially adversely affect the appearance thereof, or
materially adversely affect Tenant's use of the Premises; (ii) permit Landlord
and any mortgagee of the Building and/or the Park or of the interest of Landlord
therein, and any lessor under any ground or underlying lease, and their
representatives, to have free and unrestricted access to and to enter upon the
Premises at all reasonable hours for the purposes of inspection or of making
repairs, replacements or improvements in or to the Premises or the Building
and/or the Park or equipment (including, without limitation, sanitary,
electrical, heating, air conditioning or other systems) or of complying with all
laws, orders and requirements of governmental or other authority or of
exercising any right reserved to Landlord by this Lease (including the right
during the progress of any such repairs, replacements or improvements or while
performing work and furnishing materials in connection with compliance with any
such laws, orders or requirements to take upon or through, or to keep and store
within, the Premises all necessary materials, tools and equipment); and (iii)
permit Landlord, at reasonable times, to show the Premises during ordinary
business hours to any existing or prospective mortgagee, ground lessor, space
lessee, purchaser, or assignee of any mortgage, of the Building and/or the Park
and the land or of the interest of Landlord therein, and during the period of 12
months next preceding the Termination Date to any person contemplating the
leasing of the Premises or any part thereof. If, during the last month of the
term, Tenant shall have removed all or substantially all of Tenant's property
therefrom, Landlord may immediately enter and alter, renovate and redecorate the
Premises, without elimination or abatement of rent, or incurring liability to
Tenant for any compensation, and such acts shall have no effect upon this Lease.
In an emergency, if Tenant shall not be personally present to open and permit an
entry into the Premises, Landlord or Landlord's agents may enter the same by a
master key, or may forcibly enter the same, without rendering Landlord or such
agents liable therefor (if during such entry Landlord or Landlord's agents shall
accord reasonable care to Tenant's property), and without in any manner
affecting the obligations and covenants of this Lease. Landlord shall exercise
its rights of access to the Premises permitted under any of the terms and
provisions of this Lease in such manner as to minimize to the extent practicable
interference with Tenant's use and occupation of the Premises. If an excavation
shall be made upon land adjacent to the Premises or shall be authorized to be
made, Tenant shall afford to the person causing or authorized to cause such
excavation, license to enter upon the Premises for the purpose of doing such
work as said person shall deem necessary to preserve the Building from injury or
damage and to support the same by proper foundations without any claims for
damages or indemnity against Landlord, or

                                     -36-
<PAGE>

diminution or abatement of rent (subject, however, to the provisions of Articles
8.8, 15.4, 15.5, and 15.6 of this Lease).

         17.3  Accidents to Sanitary and Other Systems. Tenant shall give to
Landlord prompt notice of any fire or casualty in the Premises or in the
Building and of any damage to, or defective condition in, any part or
appurtenance of the Building including, without limitation, sanitary,
electrical, heating and air conditioning or other systems located in, or passing
through, the Premises of which it has actual knowledge. Tenant shall not be
required to give Landlord notice of accidents which are covered by Workers
Compensation laws. Except as otherwise provided in Articles 18, 19 and 20, and
subject to Tenant's obligations in Article 14, such damage or defective
condition shall be remedied by Landlord with reasonable diligence, but if such
damage or defective condition was caused by Tenant or by the employees,
licensees, contractors or invitees of Tenant, the cost to remedy the same shall
be paid by Tenant. Subject to the provisions of Articles 8.8, 15.4, 15.5, and
15.6 of this Lease, Tenant shall not be entitled to claim any eviction from the
Premises or any damages arising from any such damage or defect unless the same
(i) shall have been occasioned by the negligence of the Landlord, its agents,
servants or employees and (ii) shall not, after notice to Landlord of the
condition claimed to constitute negligence, have been cured or corrected within
a reasonable time after such notice has been received by Landlord; and in case
of a claim of eviction unless such damage or defective condition shall have
rendered the Premises untenantable and they shall not have been made tenantable
by Landlord within a reasonable time.

         17.4  Signs, Blinds and Drapes. Tenant shall put no signs in any part
of the Building or the Park, but Tenant shall be identified on a ground-mounted
sign located outside the Building entrance as well as on the lobby directory, on
sign panels installed by Landlord at Tenant's expense, subject to any unused
portion of Landlord's Contribution or Landlord's HVAC Contribution. No signs may
be put on or in any window or elsewhere if visible from the exterior of the
Building. Tenant may hang its own drapes or blinds, provided that they shall not
in any way interfere with the building standard drapery or blinds or be visible
from the exterior of the Building and that such drapes are so hung and installed
that when drawn, the building standard drapery or blinds are automatically also
drawn.

         17.5  Estoppel Certificate. Each party ("Responding Party") shall at
any time and from time to time upon not less than ten (10) days' prior notice
from the other party ("Requesting Party"), execute, acknowledge and deliver to
the Requesting Party a statement in writing certifying that this Lease is
unmodified and in full force and effect (or if there have been modifications,
that the same is in full force and effect as modified and stating the
modifications), and the dates to which the Yearly Rent and other charges have
been paid in advance, if any, stating whether or not the Requesting Party is in
default in performance of any covenant, agreement, term, provision or condition
contained in this Lease and, if so, specifying each such default and such other
facts as the Requesting Party may reasonably request, it being intended that any
such statement delivered pursuant hereto may be relied upon by any prospective
purchaser of the Building or of the Building and the land or of any interest of
Landlord therein, any

                                     -37-
<PAGE>

mortgagee or prospective mortgagee thereof, any lessor or prospective lessor
thereof, any lessee or prospective lessee thereof, or any prospective assignee
of any mortgage thereof, or any prospective subtenant or assignee. Time is of
the essence in respect of any such requested certificate, each party hereby
acknowledging the importance of such certificates in mortgage financing
arrangements, prospective sale and the like.

         17.6  Prohibited Materials and Property. Tenant shall not bring or
permit to be brought or kept in or on the Premises or elsewhere in the Building
or the Park any unique, unusually valuable, rare or exotic property, work of art
or the like unless the same is fully insured under all-risk coverage. Nor shall
Tenant cause or permit any odors of cooking or other processes, or any unusual
or other objectionable odors to emanate from or permeate the Premises.

         17.7  Requirements of Law--Fines and Penalties.

         (a)   Subject to the provisions of this Article 17.7, Tenant at its
sole expense shall comply with all laws, rules, orders and regulations,
including, without limitation, all energy-related requirements, of Federal,
State, County and Municipal Authorities and with any direction of any public
officer or officers, pursuant to law (collectively "Laws"), which shall impose
any duty upon Landlord or Tenant with respect to or arising out of Tenant's
particular use or occupancy of the Premises. If Tenant receives notice of any
violation of law, ordinance, order or regulation applicable to the Premises, it
shall give prompt notice thereof to Landlord.

         (b)   Landlord shall comply with all Laws relating to the performance
of Landlord Work. Landlord, subject to inclusion of the cost of compliance as
Operating Costs in accordance with the provisions of Article 9.1(g) of this
Lease, shall comply with (i) all Laws which relate to the structure of the
Building, unless the need for such compliance arises from Tenant's particular
use of the Premises, and (ii) all other Laws applicable to the Park other than
those Laws for which Tenant is responsible pursuant to Article 17.7(a) above.

         (c)   Except as otherwise disclosed on Exhibit 4, Landlord represents
and warrants to Tenant that, to the best of Landlord's knowledge, the Park is,
as of the Execution Date, in compliance with all applicable laws.

         (d)   Landlord shall comply with the Americans with Disabilities Act of
1990, and the rules and regulations promulgated thereunder ("ADA") so far as
they relate to the parking areas, other common areas of the Park, and Landlord's
Work, including, without limitation, the exterior of the building, the bathrooms
located in the Building on the Term Commencement Date, and the elevators in the
Building. Operating Costs shall not include any costs incurred by Landlord in
order to bring the parking and other common areas of the Park, other buildings
in the Park, or the Landlord's Work into compliance with the ADA, as amended
through the Execution Date (including any regulations promulgated through the
Execution Date). Tenant shall be responsible for all costs of

                                     -38-
<PAGE>

bringing the Premises (excluding any portions constructed by Landlord in the
performance of Landlord's Work) into compliance with ADA.

         17.8  Tenant's Acts--Effect on Insurance. Tenant shall not knowingly do
or permit to be done any act or thing upon the Premises or elsewhere in the
Building or the Park which Tenant knows will invalidate or be in conflict with
any insurance policies covering the Building, the Park and the fixtures and
property therein; and shall not do, or permit to be done, any act or thing upon
the Premises which shall subject Landlord to any liability or responsibility for
injury to any person or persons or to property by reason of any business or
operation being carried on upon said Premises or for any other reason. Tenant at
its own expense shall comply with all rules, orders, regulations and
requirements of the Board of Fire Underwriters, or any other similar body having
jurisdiction, and shall not (i) do, or permit anything to be done, in or upon
the Premises, or bring or keep anything therein, except as now or hereafter
permitted by the Fire Department, Board of Underwriters, Fire Insurance Rating
Organization, or other authority having jurisdiction, and then only in such
quantity and manner of storage as will not increase the rate for any insurance
applicable to the Building and/or the Park, or (ii) use the Premises in a manner
which shall increase such insurance rates on the Building, the Park or on
property located therein, over that applicable when Tenant first took occupancy
of the Premises hereunder. If by reason of the failure of Tenant to comply with
the provisions hereof the insurance rate applicable to any policy of insurance
shall at any time thereafter be higher than it otherwise would be, the Tenant
shall reimburse Landlord for that part of any insurance premiums thereafter paid
by Landlord, which shall have been charged because of such failure by Tenant.
Landlord represents to Tenant that the use permitted hereunder as described on
Exhibit 1 (as opposed to the actual manner and method of Tenant's particular
use) will not cause an increase in Landlord's insurance premiums.

         17.9  Miscellaneous. Tenant shall not suffer or permit the Premises or
any Landlord fixtures, equipment or utilities therein or serving the same, to be
overloaded, damaged or defaced, nor permit any hole to be drilled or made in any
part thereof. Tenant shall not suffer or permit any employee, contractor,
business invitee or visitor to violate any covenant, agreement or obligations of
the Tenant under this Lease.

18.      DAMAGE BY FIRE, ETC.

         18.1  Casualty Insurance. During the entire term of this Lease, and
adjusting insurance coverages to reflect current values from time to time: (i)
so long as the same is available at commercially reasonable rates, Landlord
shall maintain so called All Risk property insurance on the Building at
replacement cost value, as reasonably estimated by Landlord (excluding any
alterations, installations or additions made by Tenant and any other property
installed by or at the expense of Tenant [referred to collectively herein as
"Above Base Building Work"]); and (ii) Tenant shall keep its personal property
in and about the Premises and any other property installed by or at the expense
of Tenant insured against loss or damage caused by any peril covered under fire,
extended coverage and all risk insurance in an amount equal to ninety percent
(90%) of the full replacement

                                     -39-
<PAGE>

cost thereof. Such Tenant's insurance shall insure the interests of both
Landlord and Tenant as their respective interests may appear from time to time
and shall name Landlord as an additional insured with respect to the leasehold
improvements made by or at the expense of Tenant; and the proceeds thereof shall
be used only for the replacement or restoration of the Above Base Building Work.

         18.2  Repair of Damage Caused by Casualty. If any portion of the
Premises required to be insured by Landlord under Article 18.1 shall be damaged
by fire or other insured casualty, Landlord shall proceed with diligence,
subject to the then applicable statutes, building codes, zoning ordinances, and
regulations of any governmental authority, and at the expense of Landlord (but
only to the extent of insurance proceeds made available to Landlord by any
mortgagee and/or ground lessor of the real property of which the Premises are a
part) to repair or cause to be repaired such damage, provided, however, that any
repairs to Above Base Building Work or other property installed by Tenant which
is damaged by such fire or other casualty which (in the reasonable judgment of
Landlord) can more effectively be repaired as an integral part of Landlord's
repair work on the Premises, such repairs shall be performed by Landlord but at
Tenant's expense; in all other respects, all repairs to and replacements of
Above Base Building Work and such other property shall be made by and at the
expense of Tenant. If the Premises or any part thereof shall have been rendered
unfit for use and occupation hereunder by reason of such damage the Yearly Rent
and other charges or a just and proportionate part thereof, according to the
nature and extent to which the Premises shall have been so rendered unfit, shall
be suspended or abated until the earlier of: (x) ninety (90) days after the
Premises (except as to the property which is to be repaired by or at the expense
of Tenant) shall have been restored as nearly as practicably may be to the
condition in which they were immediately prior to such fire or other casualty,
or (y) the date that Tenant first recommences its use and occupancy of the
Premises or any portion thereof. Tenant agrees to cooperate with Landlord and
Landlord's Mortgagee in such manner as Landlord may reasonably request in
assisting Landlord and Landlord's Mortgagee in collecting insurance proceeds
(including rent insurance proceeds) due in connection with any casualty
affecting the Premises. Landlord shall not be liable for delays in the making of
any such repairs which are due to government regulation, casualties and strikes,
unavailability of labor and materials, and other causes beyond the reasonable
control of Landlord (financial inability shall not be deemed to constitute
causes beyond Landlord's reasonable control), nor shall Landlord be liable for
any inconvenience or annoyance to Tenant or injury to the business of Tenant
resulting from delays in repairing such damage.

         18.3  Landlord's Termination Rights. If (i) the Premises are so damaged
by fire or other casualty (whether or not insured) at any time during the last
twelve (12) months of the term hereof that the cost to repair such damage is
reasonably estimated to exceed one-half of the total Yearly Rent payable
hereunder for the period from the estimated date of restoration until the
Termination Date, or (ii) the Building or the Park is so damaged by fire or
other casualty (whether or not insured) that substantial alteration or
reconstruction or demolition of the Building shall in Landlord's good faith
judgment be required, then and in either of such events, this Lease and the term
hereof may be

                                     -40-
<PAGE>

terminated at the election of Landlord by a notice in writing of its election so
to terminate which shall be given by Landlord to Tenant within thirty (30) days
following such fire or other casualty, the effective termination date of which
shall be not less than thirty (30) days after the day on which such termination
notice is received by Tenant. Notwithstanding the foregoing, Landlord will not
be entitled to terminate this Lease solely because there is less than two (2)
years on the Lease Term if Tenant has an exercisable right to renew or extend
the term of the Lease and Tenant, within ten (10) days after receipt of
Landlord's notice of termination, validly exercises such right. The foregoing
shall not prohibit Landlord from exercising its right to terminate for any of
the other reasons set forth herein.

         18.4  Tenant's Termination Right.

         (a)   Tenant shall have the right to terminate this Lease if all of the
following conditions occur: (1) a substantial portion of the Premises has been
damaged by fire or other casualty and such damage cannot reasonably be repaired
within sixty (60) days after the date of such fire or other casualty; and (2)
there is less than one (1) year of the term of the Lease remaining on the date
of such casualty; and (3) the casualty was not caused by the negligence or
willful misconduct of Tenant or its agents, employees or contractors; and (4)
Tenant provides Landlord with written notice of its intent to terminate within
thirty (30) days after the date of the fire or other casualty.

         (b)   If any portion of the Premises or any portion of the Building
shall be damaged or destroyed by fire or other casualty to the extent that the
operation of Tenant's business in the Premises in the normal course is
materially adversely affected, then, within thirty (30) days of such fire or
other casualty, Landlord shall submit to Tenant a reasonable engineering
estimate as to the estimated length of time to complete such repairs. If the
time period ("Estimated Restoration Period") set forth in such estimate shall
exceed two hundred seventy (270) days of the date of such casualty, Tenant may
elect, by a notice sent within fifteen (15) days after notice of such estimate
is sent to Tenant, to terminate this Lease. If such estimate shall fall within
the 270-day limit, Tenant shall have no such right to terminate and Landlord
shall, subject to the provisions of this Article 18, proceed with due diligence
and promptness to reasonably complete the repairs or restoration within such two
hundred seventy (270) days, subject always to delays for causes beyond
Landlord's reasonable control including, but not limited to the causes specified
in Article 26 hereof, and the other limitations set forth in this Article 18.

         (c)   In the event that the Premises or the Building are damaged by
fire or other casualty to such an extent so as to render the Premises
untenantable, and if Landlord shall fail to substantially complete said repairs
or restoration within two hundred seventy (270) days after the date of such fire
or other casualty for any reason other than Tenant's fault, Tenant may terminate
this Lease by giving Landlord written notice as follows:

               (i) Said notice shall be given after said two hundred seventy day
               period.


                                     -41-
<PAGE>

               (ii) Said notice shall set forth an effective date which is not
               earlier than thirty (30) days after Landlord receives said
               notice.

               (iii) If said repairs or restoration are substantially complete
               on or before the date thirty (30) days (which thirty-(30)-day
               period shall be extended by the length of any delays caused by
               Tenant or Tenant's contractors) after Landlord receives such
               notice, said notice shall have no further force and effect.

               (iv) If said repairs or restoration are not substantially
               complete on or before the date thirty (30) days (which
               thirty-(30)-day period shall be extended by the length of any
               delays caused by Tenant or Tenant's contractors) after Landlord
               receives such notice, the Lease shall terminate as of said
               effective date.


         18.5  General Provisions Relating to Any Casualty Termination.

         In the event of any termination, this Lease and the term hereof shall
expire as of such effective termination date as though that were the Termination
Date as stated in Exhibit 1 and the Yearly Rent and other charges payable under
this Lease shall be apportioned as of such date; and if the Premises or any part
thereof shall have been rendered unfit for use and occupation by reason of such
damage the Yearly Rent and other charges for the period from the date of the
fire or other casualty to the effective termination date, or a just and
proportionate part thereof, according to the nature and extent to which the
Premises shall have been so rendered unfit, shall be abated.

19.      WAIVER OF SUBROGATION

         Notwithstanding anything set forth in this Lease to the contrary,
Landlord and Tenant do hereby waive any and all right of recovery, claim, action
or cause of action against the other, their respective principals,
beneficiaries, partners, officers, directors, agents, and employees, and, with
respect to Landlord, its Mortgagee(s), for any loss or damage that may occur to
Landlord or Tenant or any party claiming by, through or under Landlord or
Tenant, as the case may be, with respect to their respective property, the
Building or the Premises or any addition or improvements thereto, or any
contents therein, by reason of fire, the elements or any other cause, regardless
of cause or origin, including the negligence of Landlord or Tenant, or their
respective principals, beneficiaries, partners, officers, directors, agents and
employees and, with respect to Landlord, its Mortgagee(s), which loss or damage
is (or would have been, had the insurance required by this Lease been carried)
covered by insurance. Since this mutual waiver will preclude the assignment of
any such claim by subrogation (or otherwise) to an insurance company (or any
other person), Landlord and Tenant each agree to give each insurance company
which has issued, or in the future may issue, policies of insurance, with
respect to the items covered by this waiver, written notice of the terms of this
mutual waiver, and to have such insurance policies properly endorsed, if
necessary,

                                     -42-
<PAGE>

to prevent the invalidation of any of the coverage provided by such insurance
policies by reason of such mutual waiver. For the purpose of the foregoing
waiver, the amount of any deductible applicable to any loss or damage shall be
deemed covered by, and recoverable by the insured under the insurance policy to
which such deductible relates. In the event that Tenant is permitted to and
self-insures any risk which would have been covered by the insurance required to
be carried by Tenant pursuant to Article 18 of the Lease, or if Tenant fails to
carry any insurance required to be carried by Tenant pursuant to Article 18 of
this Lease, then all loss or damage to Tenant, its leasehold interest, its
business, its property, the Premises or any additions or improvements thereto or
contents thereof shall be deemed covered by and recoverable by Tenant under
valid and collectible policies of insurance.

20.      CONDEMNATION - EMINENT DOMAIN

         20.1  Landlord's Termination Rights. In the event that the Premises or
any part thereof, or the whole or any material part of the Park, shall be taken
or appropriated by eminent domain or shall be condemned for any public or
quasi-public use, or (by virtue of any such taking, appropriation or
condemnation) shall suffer any damage (direct, indirect or consequential) for
which Landlord or Tenant shall be entitled to compensation, so that, in
Landlord's bona fide business judgment, the continued operation of the Park
shall be rendered uneconomic, then (and in any such event) this Lease and the
term hereof may be terminated at the election of Landlord by a notice in writing
of its election so to terminate which shall be given by Landlord to Tenant
within sixty (60) days following the date on which Landlord shall have received
notice of such taking, appropriation or condemnation. Such termination shall be
effective in accordance with Article 20.3.

         20.2  Tenant's Termination Rights. In the event that a material part of
the Premises, the means of access thereto, or the Parking Areas shall be so
taken, appropriated or condemned, so that, in Tenant's bona fide business
judgment, the continued operation of Tenant's business in the Premises is
materially adversely affected, then (and in any such event) this Lease and the
term hereof may be terminated at the election of Tenant by a notice in writing
of its election so to terminate which shall be given by Tenant to Landlord
within sixty (60) days following the date on which Tenant shall have received
notice of such taking, appropriation or condemnation. Such termination shall be
effective in accordance with Article 20.3.

         20.3  General Taking Provisions. Upon the giving of any notice of
termination (either by Landlord or Tenant) this Lease and the term hereof shall
terminate on or retroactively as of the date on which Tenant shall be required
to vacate any part of the Premises or shall be deprived of a substantial part of
the means of access thereto, provided, however, that Landlord may in Landlord's
notice elect to terminate this Lease and the term hereof retroactively as of the
date on which such taking, appropriation or condemnation became legally
effective. In the event of any such termination, this Lease and the term hereof
shall expire as of such effective termination date as though that were the
Termination Date as stated in Exhibit 1, and the Yearly Rent shall be
apportioned as

                                     -43-
<PAGE>

of such date. If neither party (having the right so to do) elects to terminate
Landlord will, with reasonable diligence and at Landlord's expense, restore the
remainder of the Premises, or the remainder of the means of access, as nearly as
practicably may be to the same condition as obtained prior to such taking,
appropriation or condemnation in which event (i) the Total Rentable Area shall
be adjusted as in Exhibit 5 provided, (ii) a just proportion of the Yearly Rent,
according to the nature and extent of the taking, appropriation or condemnation
and the resulting permanent injury to the Premises and the means of access
thereto, shall be permanently abated, and (iii) a just proportion of the
remainder of the Yearly Rent, according to the nature and extent of the taking,
appropriation or condemnation and the resultant injury sustained by the Premises
and the means of access thereto, shall be abated until what remains of the
Premises and the means of access thereto shall have been restored as fully as
may be for permanent use and occupation by Tenant hereunder.

         20.4  Taking Proceeds. Except for any award specifically reimbursing
Tenant for moving or relocation expenses, there are expressly reserved to
Landlord all rights to compensation and damages created, accrued or accruing by
reason of any such taking, appropriation or condemnation, in implementation and
in confirmation of which Tenant does hereby acknowledge that Landlord shall be
entitled to receive all such compensation and damages, grant to Landlord all and
whatever rights (if any) Tenant may have to such compensation and damages, and
agree to execute and deliver all and whatever further instruments of assignment
as Landlord may from time to time request.

         20.5  Temporary Takings. In the event of any taking of the Premises or
any part thereof for temporary use (i.e. not in excess of two hundred
twenty-five days): (i) this Lease shall be and remain unaffected thereby, and
(ii) Tenant shall be entitled to receive for itself any award made for such use,
provided, that if any taking is for a period extending beyond the term of this
Lease, such award shall be apportioned between Landlord and Tenant as of the
Termination Date or earlier termination of this Lease.

21.      DEFAULT

         21.1  Conditions of Limitation - Re-entry - Termination. This Lease and
the herein term and estate are, upon the condition that if (a) subject to
Article 21.7, Tenant shall neglect or fail to perform or observe any of the
Tenant's covenants or agreements herein, including (without limitation) the
covenants or agreements with regard to the payment when due of Rent, additional
charges, reimbursement for increase in Landlord's costs, or any other charge
payable by Tenant to Landlord in accordance with the provisions of this Lease
(all of which shall be considered as part of Rent for the purposes of invoking
Landlord's statutory or other rights and remedies in respect of payment
defaults); or (b) Tenant shall be involved in financial difficulties as
evidenced by an admission in writing by Tenant of Tenant's inability to pay its
debts generally as they become due, or by the making or offering to make a
composition of its debts with its creditors; or (c) Tenant shall make an
assignment or trust mortgage, or other conveyance or transfer of like nature, of
all or a substantial part of its property for the benefit of its creditors, or
(d) the leasehold hereby created shall be taken on execution or by other

                                     -44-
<PAGE>

process of law and shall not be revested in Tenant within thirty (30) days
thereafter; or (e) a receiver, sequesterer, trustee or similar officer shall be
appointed by a court of competent jurisdiction to take charge of all or any part
of Tenant's property and such appointment shall not be vacated within ninety
(90) days; or (f) any proceeding shall be instituted by or against Tenant
pursuant to any of the provisions of any Act of Congress or State law relating
to bankruptcy, reorganizations, arrangements, compositions or other relief from
creditors, and, in the case of any proceeding instituted against it, if Tenant
shall fail to have such proceedings dismissed within ninety (90) days or if
Tenant is adjudged bankrupt or insolvent as a result of any such proceeding, or
(g) any event shall occur or any contingency shall arise whereby this Lease, or
the term and estate thereby created, would (by operation of law or otherwise)
devolve upon or pass to any person, firm or corporation other than Tenant,
except as expressly permitted under Article 16 hereof - then, and in any such
event (except as hereinafter in Article 21.2 otherwise provided) Landlord may,
by notice to Tenant, elect to terminate this Lease; and thereupon (and without
prejudice to any remedies which might otherwise be available for arrears of rent
or other charges due hereunder or preceding breach of covenant or agreement and
without prejudice to Tenant's liability for damages as hereinafter stated), upon
the giving of such notice, this Lease shall terminate as of the date specified
therein as though that were the Termination Date as stated in Exhibit 1. Without
being taken or deemed to be guilty of any manner of trespass or conversion, and
without being liable to indictment, prosecution or damages therefor, Landlord
may, forcibly if necessary, enter into and upon the Premises (or any part
thereof in the name of the whole); repossess the same as of its former estate;
and expel Tenant and those claiming under Tenant. Wherever "Tenant " is used in
subdivisions (b), (c), (e) and (f) of this Article 21.1, it shall be deemed to
include any guarantor of any of Tenant's obligations under this Lease. The words
"re-entry" and "re-enter" as used in this Lease are not restricted to their
technical legal meanings.

         21.2  Damages - Assignment for Benefit of Creditors. For the more
effectual securing to Landlord of the rent and other charges and payments
reserved hereunder, it is agreed as a further condition of this Lease that if at
any time Tenant shall make any transfer similar to or in the nature of an
assignment of its property for the benefit of its creditors, the term and estate
hereby created shall terminate ipso facto, without entry or other action by
Landlord; and notwithstanding any other provisions of this Lease, Landlord shall
forthwith upon such termination, without prejudice to any remedies which might
otherwise be available for arrears of rent or other charges due hereunder or
preceding breach of this Lease, be ipso facto entitled to recover as liquidated
damages the sum of (a) the amount described in clause (x) of Article 21.3 and
(b) (in view of the uncertainty of prompt re-letting and the expense entailed in
re-letting the Premises) an amount equal to the rent and other charges payable
for and in respect of the twelve-(12)-month period next preceding the date of
termination, as aforesaid.

         21.3  Damages - Termination.

         (a)   Upon the termination of this Lease under the provisions of this
Article 21, then except as hereinabove in Article 21.2 otherwise provided,
Tenant shall pay to Landlord the Rent and other charges payable by Tenant to
Landlord up to the time of

                                     -45-
<PAGE>

such termination, shall continue to be liable for any preceding breach of
covenant, and in addition, shall pay to Landlord as damages, at the election of
Landlord

                                     either:

               (x) the amount (discounted to present value) by which, at the
         time of the termination of this Lease (or at any time thereafter if
         Landlord shall have initially elected damages under subparagraph (y),
         below), (i) the aggregate of the Rent and other charges projected over
         the period commencing with such termination and ending on the
         Termination Date as stated in Exhibit 1 exceeds (ii) the aggregate Fair
         Market Rental Value of the Premises for such period;

                                       or:

               (y) amounts equal to the Rent and other charges which would have
         been payable by Tenant had this Lease not been so terminated, payable
         upon the due dates therefor specified herein following such termination
         and until the Termination Date as specified in Exhibit 1, provided,
         however, if Landlord shall re-let the Premises during such period, that
         Landlord shall credit Tenant with the net rents received by Landlord
         from such re-letting, such net rents to be determined by first
         deducting from the gross rents as and when received by Landlord from
         such re-letting the expenses incurred or paid by Landlord in
         terminating this Lease, as well as the expenses of re-letting,
         including altering and preparing the Premises for new tenants, brokers'
         commissions, and all other similar and dissimilar expenses properly
         chargeable against the Premises and the rental therefrom, it being
         understood that any such re-letting may be for a period equal to or
         shorter or longer than the remaining term of this Lease; and provided,
         further, that (i) in no event shall Tenant be entitled to receive any
         excess of such net rents over the sums payable by Tenant to Landlord
         hereunder and (ii) in no event shall Tenant be entitled in any suit for
         the collection of damages pursuant to this Subparagraph (y) to a credit
         in respect of any net rents from a re-letting except to the extent that
         such net rents are actually received by Landlord prior to the
         commencement of such suit. If the Premises or any part thereof should
         be re-let in combination with other space, then proper apportionment on
         a square foot area basis shall be made of the rent received from such
         re-letting and of the expenses of re-letting.

In calculating the Rent and other charges under Subparagraph (x), above, there
shall be included, in addition to the Yearly Rent, Tax Excess and Operating
Expense Excess and all other considerations agreed to be paid or performed by
Tenant, on the assumption that all such amounts and considerations would have
remained constant (except as herein otherwise provided) for the balance of the
full term hereby granted.

         (b)   Suit or suits for the recovery of such damages, or any
installments thereof, may be brought by Landlord from time to time at its
election, and nothing contained

                                     -46-
<PAGE>

herein shall be deemed to require Landlord to postpone suit until the date when
the term of this Lease would have expired if it had not been terminated
hereunder.

         (c)   Nothing herein contained shall be construed as limiting or
precluding the recovery by Landlord against Tenant of any sums or damages to
which, in addition to the damages particularly provided above, Landlord may
lawfully be entitled by reason of any default hereunder on the part of Tenant.

         (d)   Landlord agrees to use reasonable efforts to relet the Premises
after Tenant vacates the Premises in the event that the Lease is terminated
based upon a default by Tenant hereunder. Marketing of Tenant's Premises in a
manner similar to the manner in which Landlord markets other Premises within
Landlord's control in the Park shall be deemed to have satisfied Landlord's
obligation to use "reasonable efforts." In no event shall Landlord be required
to (i) solicit or entertain negotiations with any other prospective tenants for
the Premises until Landlord obtains full and complete possession of the Premises
including, without limitation, the final and unappealable legal right to re-let
the Premises free of any claim of Tenant, (ii) relet the Premises before leasing
other vacant space in the Park, and (iii) lease the Premises for a rental less
than the current fair market rental then prevailing for similar space in the
Park.

         21.4  Fees and Expenses.

         (a)   Landlord's Self Help. If Tenant shall default in the performance
of any covenant on Tenant's part to be performed as in this Lease contained,
Landlord may, upon thirty (30) days prior written notice to Tenant (except that,
in emergency situations, no notice shall be required) perform the same for the
account of Tenant. If Landlord at any time is compelled to pay or elects to pay
any sum of money, or do any act which will require the payment of any sum of
money, by reason of the failure of Tenant to comply with any provision hereof,
or if Landlord is compelled to or does incur any expense, including reasonable
attorneys' fees, in instituting, prosecuting, and/or defending any action or
proceeding instituted by reason of any default of Tenant hereunder, Tenant shall
on demand pay to Landlord by way of reimbursement the sum or sums reasonably
paid by Landlord with all costs and damages, plus (if applicable) interest
computed as provided in Article 6 hereof.

         (b)   In the event of any litigation between Landlord and Tenant, the
losing party shall reimburse the prevailing party for its reasonable attorneys
fees and costs incurred in connection with such litigation.

         21.5  Waiver of Redemption.  Intentionally Omitted.

         21.6  Remedies Not Exclusive. Unless otherwise specified in this Lease,
the specified remedies to which Landlord may resort hereunder are cumulative and
are not intended to be exclusive of any remedies or means of redress to which
Landlord may at any time be lawfully entitled, and either party may invoke any
remedy (including the

                                     -47-
<PAGE>

remedy of specific performance) allowed at law or in equity as if specific
remedies were not herein provided for.

         21.7  Grace Period. Notwithstanding anything to the contrary in this
Lease contained, Landlord agrees not to take any action to terminate this Lease
(a) for default by Tenant in the payment when due of any sum of money, if Tenant
shall cure such default within ten (10) days after written notice thereof is
given by Landlord to Tenant, provided, however, that no such notice need be
given and no such default in the payment of money shall be curable if on two (2)
prior occasions in the same twelve month period, there had been a default in the
payment of money which had been cured after notice thereof had been given by
Landlord to Tenant as herein provided or (b) for default by Tenant in the
performance of any covenant other than a covenant to pay a sum of money, if
Tenant shall cure such default within a period of thirty (30) days after written
notice thereof given by Landlord to Tenant (except where the nature of the
default is such that remedial action should appropriately take place sooner, as
indicated in such written notice), or within such additional period as may
reasonably be required to cure such default if (because of governmental
restrictions or any other cause beyond the reasonable control of Tenant) the
default is of such a nature that it cannot be cured within such thirty-(30)-day
period, provided, however, (1) that there shall be no extension of time beyond
such thirty-(30)-day period for the curing of any such non-monetary default
unless, not more than twenty (20) days after the receipt of the notice of
default, Tenant in writing (i) shall specify the cause on account of which the
default cannot be cured during such period and shall advise Landlord of its
intention duly to institute all steps necessary to cure the default and (ii)
shall, as soon as reasonably practicable, duly institute and thereafter
diligently prosecute to completion all steps necessary to cure such default and,
(2) that no notice of the opportunity to cure a non-monetary default need be
given, and no grace period whatsoever shall be allowed to Tenant, if the
condition on which Landlord seeks to terminate this Lease is based upon
subdivisions (b), (c), (d), (e), (f) or (g) of Article 21.1.

22.      END OF TERM - ABANDONED PROPERTY

         (a)   Upon the expiration or other termination of the term of this
Lease, Tenant shall peaceably quit and surrender to Landlord the Premises and
all alterations and additions thereto, broom clean, in good order, repair and
condition (except as provided herein and in Articles 8.7, 18 and 20) excepting
only ordinary wear and use and damage by fire or other casualty for which, under
other provisions of this Lease, Tenant has no responsibility of repair or
restoration. Subject to Article 12, Tenant shall remove all of its property and,
to the extent specified by Landlord, all alterations and additions made by
Tenant and all partitions wholly within the Premises, and shall repair any
damages to the Premises, the Park or the Building caused by their installation
or by such removal. Tenant's obligation to observe or perform this covenant
shall survive the expiration or other termination of the term of this Lease.

         (b)   Tenant will remove any personal property from the Building, the
Park and the Premises upon or prior to the expiration or termination of this
Lease and any such

                                     -48-
<PAGE>

property which shall remain in the Building or the Premises thereafter shall be
conclusively deemed to have been abandoned, and may either be retained by
Landlord as its property or sold or otherwise disposed of in such manner as
Landlord may see fit. If any part thereof shall be sold, Landlord may receive
and retain the proceeds of such sale and apply the same, at its option, against
the expenses of the sale, the cost of moving and storage, any arrears of Yearly
Rent, additional or other charges payable hereunder by Tenant to Landlord and
any damages to which Landlord may be entitled under Article 21 hereof or
pursuant to law.

         (c)   If Tenant or anyone claiming under Tenant shall remain in
possession of the Premises or any part thereof after the expiration or prior
termination of the term of this Lease without any agreement in writing between
Landlord and Tenant with respect thereto, then, prior to the acceptance of any
payments for rent or use and occupancy by Landlord, the person remaining in
possession shall be deemed a tenant-at-sufferance. Whereas the parties hereby
acknowledge that Landlord may need the Premises after the expiration or prior
termination of the term of the Lease for other tenants and that the damages
which Landlord may suffer as the result of Tenant's holding-over cannot be
determined as of the Execution Date hereof, in the event that Tenant so holds
over, Tenant shall pay to Landlord in addition to all rental and other charges
due and accrued under the Lease prior to the date of termination, charges (based
upon fair market rental value of the Premises) for use and occupation of the
Premises thereafter and, in addition to such sums and any and all other rights
and remedies which Landlord may have at law or in equity, an additional use and
occupancy charge in the amount of fifty percent (50%) of either the Yearly Rent
and other charges calculated (on a daily basis) at the highest rate payable
under the terms of this Lease, but measured from the day on which Tenant's
hold-over commenced and terminating on the day on which Tenant vacates the
Premises or the fair market value of the Premises for such period, whichever is
greater. In addition, if Landlord is unable to deliver possession of the
Premises to a new tenant, or to perform improvements for a new tenant, as a
result of Tenant's holdover and Tenant fails to vacate the Premises within 15
days after Landlord notifies Tenant of Landlord's inability to deliver
possession or perform improvements, Tenant shall save Landlord, its agents and
employees, harmless and will exonerate, defend and indemnify Landlord, its
agents and employees, from and against any and all damages which Landlord may
suffer on account of Tenant's hold-over in the Premises after the expiration or
prior termination of the term of the Lease.

23.      SUBORDINATION

         (a)   Subject to any mortgagee's or ground lessor's election, as
hereinafter provided for, this Lease is subject and subordinate in all respects
to all matters of record (including, without limitation, deeds and land
disposition agreements) and all mortgages, any of which may now or hereafter be
placed on or affect such leases and/or the real property of which the Premises
are a part, or any part of such real property, and/or Landlord's interest or
estate therein, and to each advance made and/or hereafter to be made under any
such mortgages, and to all renewals, modifications, consolidations, replacements
and extensions thereof and all substitutions therefor. This Article 23 shall

                                     -49-
<PAGE>

be self-operative and no further instrument or subordination shall be required.
In confirmation of such subordination, Tenant shall execute, acknowledge and
deliver promptly any certificate or instrument that Landlord and/or any
mortgagee and/or their respective successors in interest may reasonably request.
Notwithstanding anything to the contrary in this Article 23 contained, as to any
future mortgages, ground leases, and/or underlying lease or deeds of trust, the
herein provided subordination and attornment shall be effective only if the
mortgagee, ground lessor or trustee therein, as the case may be, agrees, by a
written instrument in recordable form and in the customary form of such
mortgagee, ground lessor, or trustee ("Nondisturbance Agreement") that, as long
as Tenant shall not be in terminable default of the obligations on its part to
be kept and performed under the terms of this Lease, this Lease will not be
affected and Tenant's possession hereunder will not be disturbed by any default
in, termination, and/or foreclosure of, such mortgage, ground lease, and/or
underlying lease or deed of trust, as the case may be. Landlord hereby
represents to Tenant that, as of the date of this Lease, there is no mortgage
affecting the Building or the Premises.

         (b)   Any such mortgagee or ground lessor may from time to time
subordinate or revoke any such subordination of the mortgage or ground lease
held by it to this Lease. Such subordination or revocation, as the case may be,
shall be effected by written notice to Tenant and by recording an instrument of
subordination or of such revocation, as the case may be, with the appropriate
registry of deeds or land records and to be effective without any further act or
deed on the part of Tenant. In confirmation of such subordination or of such
revocation, as the case may be, Tenant shall execute, acknowledge and promptly
deliver any certificate or instrument that Landlord, any mortgagee or ground
lessor may reasonably request.

         (c)   Without limitation of any of the provisions of this Lease, if any
ground lessor or mortgagee shall succeed to the interest of Landlord by reason
of the exercise of its rights under such ground lease or mortgage (or the
acceptance of voluntary conveyance in lieu thereof) or any third party
(including, without limitation, any foreclosure purchaser or mortgage receiver)
shall succeed to such interest by reason of any such exercise or the expiration
or sooner termination of such ground lease, however caused, then such successor
may, upon notice and request to Tenant (which, in the case of a ground lease,
shall be within thirty (30) days after such expiration or sooner termination),
succeed to the interest of Landlord under this Lease, subject to such
limitations on such successor's liability as are set forth in the Nondisturbance
Agreement. In the event of such succession to the interest of the Landlord --
and notwithstanding that any such mortgage or ground lease may antedate this
Lease -- the Tenant shall attorn to such successor and shall ipso facto be and
become bound directly to such successor in interest to Landlord to perform and
observe all the Tenant's obligations under this Lease without the necessity of
the execution of any further instrument. Nevertheless, Tenant agrees at any time
and from time to time during the term hereof to execute a suitable instrument in
confirmation of Tenant's agreement to attorn, as aforesaid in a form reasonably
acceptable to Tenant.

                                     -50-
<PAGE>

         (d)   The term "mortgage(s)" as used in this Lease shall include any
mortgage or deed of trust. The term "mortgagee(s)" as used in this Lease shall
include any mortgagee or any trustee and beneficiary under a deed of trust or
receiver appointed under a mortgage or deed of trust. The term "mortgagor(s)" as
used in this Lease shall include any mortgagor or any grantor under a deed of
trust.

         (e)   Tenant agrees to send to any mortgagee (ground lessor and/or
trustee) of which Tenant shall have been previously advised in writing
("Mortgagee") a copy of any notice of default given to Landlord at the same time
as such notice is given to Landlord. Tenant further agrees that if Landlord
shall have failed to cure such default within the time provided for in this
Lease, then Mortgagee shall have the following additional periods of time to
cure such default before Tenant is entitled to exercise its rights under the
Lease:

         Abatement of Rent:   Mortgagee shall have no additional periods of time
                              to cure Landlord's defaults prior to the
                              commencement of Tenant's rent abatement rights
                              under Articles 8.8, 15.6, 18, and 20 of the Lease.

         Tenant's Termination Rights:

                              With respect to any right which Tenant has to
                              terminate the Lease based upon Landlord's default,
                              other than Tenant's right to terminate the Lease
                              based upon Landlord's failure timely to
                              Substantially Complete the Base Building Work as
                              set forth in Article 4.1 (with respect to which
                              Mortgagee shall have no additional cure period),
                              but including Tenant's termination rights under
                              Articles 8.8, 15.6, and 18 of the Lease, Mortgagee
                              shall have an additional thirty (30) days after
                              receipt of written notice that Landlord's cure
                              period has elapsed within which to cure such
                              default, provided however, that if such default
                              cannot be cured within that time, then Mortgagee
                              shall have such additional time, not to exceed
                              ninety (90) additional days, after Mortgagee's
                              receipt of written notice that Landlord's cure
                              period has elapsed, as may be reasonably necessary
                              to cure such default, if within such thirty (30)
                              day period, (i) Mortgagee gives written notice
                              ("Mortgagee's Intent Notice") to Tenant that it
                              will cure such default as soon as possible, and
                              (ii) Mortgagee has commenced and thereafter
                              diligently pursues the remedies necessary to cure
                              such default (including, but not limited to,
                              commencement of foreclosure proceedings if
                              necessary to effect such cure), in which event the
                              Lease shall not be terminated by Tenant within the
                              thirty or ninety-day period, as applicable, while
                              such remedies are being so diligently pursued.

                                     -51-
<PAGE>

24.      QUIET ENJOYMENT

         Landlord covenants that if, Tenant is not in default, beyond the
expiration of any applicable grace period, Tenant shall quietly enjoy the
Premises and its appurtenant rights from and against the claims of all persons
claiming by, through or under Landlord subject, nevertheless, to the covenants,
agreements, terms, provisions and conditions of this Lease and to the mortgages,
ground leases and/or underlying leases to which this Lease is subject and
subordinate, as hereinabove set forth.

         Without incurring any liability to Tenant, Landlord may permit access
to the Premises and open the same, whether or not Tenant shall be present, upon
any demand of any receiver, trustee, assignee for the benefit of creditors,
sheriff, marshal or court officer entitled to, or reasonable purporting to be
entitled to, such access for the purpose of taking possession of, or removing,
Tenant's property or for any other lawful purpose (but this provision and any
action by Landlord hereunder shall not be deemed a recognition by Landlord that
the person or official making such demand has any right or interest in or to
this Lease, or in or to the Premises), or upon demand of any representative of
the fire, police, building, sanitation or other department of the city, state or
federal governments.

25.      ENTIRE AGREEMENT -- WAIVER -- SURRENDER

         25.1  Entire Agreement. This Lease and the Exhibits made a part hereof
contain the entire and only agreement between the parties with respect to the
Premises, the Building and the Park, and any and all statements and
representations, written and oral, including previous correspondence and
agreements between the parties hereto, are merged herein. Tenant acknowledges
that all representations and statements upon which it relied in executing this
Lease are contained herein and that the Tenant in no way relied upon any other
statements or representations, written or oral. Any executory agreement
hereafter made shall be ineffective to change, modify, discharge or effect an
abandonment of this Lease in whole or in part unless such executory agreement is
in writing and signed by the party against whom enforcement of the change,
modification, discharge or abandonment is sought.

         25.2  Waiver. The failure of either party to seek redress for
violation, or to insist upon the strict performance, of any covenant or
condition of this Lease, or any of the Rules and Regulations promulgated
hereunder, shall not prevent a subsequent act, which would have originally
constituted a violation, from having all the force and effect of an original
violation. The receipt by Landlord of Rent with knowledge of the breach of any
covenant of this Lease shall not be deemed a waiver of such breach. The failure
of Landlord to enforce any of such Rules and Regulations against Tenant and/or
any other tenant in the Building shall not be deemed a waiver of any such Rules
and Regulations. No provisions of this Lease shall be deemed to have been waived
by either unless such waiver be in writing signed by Landlord. No payment by
Tenant or receipt by Landlord of a lesser amount than the monthly Rent herein
stipulated shall be deemed to be other than on account of the stipulated rent,
nor shall any endorsement or statement on any

                                      52
<PAGE>

check or any letter accompanying any check or payment as Rent be deemed an
accord and satisfaction, and Landlord may accept such check or payment without
prejudice to Landlord's right to recover the balance of such rent or pursue any
other remedy in this Lease provided.

         25.3  Surrender. No act or thing done by Landlord during the term
hereby demised shall be deemed an acceptance of a surrender of the Premises, and
no agreement to accept such surrender shall be valid, unless in writing signed
by Landlord. No employee of Landlord or of Landlord's agents shall have any
power to accept the keys of the Premises prior to the termination of this Lease.
The delivery of keys to any employee of Landlord or of Landlord's agents shall
not operate as a termination of the Lease or a surrender of the Premises. In the
event that Tenant at any time desires to have Landlord underlet the Premises for
Tenant's account, Landlord or Landlord's agents are authorized to receive the
keys for such purposes without releasing Tenant from any of the obligations
under this Lease, and Tenant hereby relieves Landlord of any liability for loss
of or damage to any of Tenant's effects in connection with such underletting.

26.      INABILITY TO PERFORM - EXCULPATORY CLAUSE

         Except as expressly provided in this Lease, this Lease and the
obligations of Tenant to pay Rent hereunder and perform all the other covenants,
agreements, terms, provisions and conditions hereunder on the part of Tenant to
be performed shall in no way be affected, impaired or excused because Landlord
is unable to fulfill any of its obligations under this Lease or is unable to
supply or is delayed in supplying any service expressly or impliedly to be
supplied or is unable to make or is delayed in making any repairs, replacements,
additions, alterations, improvements or decorations or is unable to supply or is
delayed in supplying any equipment or fixtures if Landlord is prevented or
delayed from so doing by reason of strikes or labor troubles or any other cause
whatsoever beyond Landlord's control, including but not limited to, governmental
preemption in connection with a national emergency or by reason of any rule,
order or regulation of any department or subdivision thereof of any governmental
agency or by reason of the conditions of supply and demand which have been or
are affected by war, hostilities or other emergency. Financial inability shall
not be considered a cause beyond Landlord's reasonable control excusing
Landlord's performance hereunder. In each such instance of inability of Landlord
to perform, Landlord shall exercise reasonable diligence to eliminate the cause
of such inability to perform.

         Tenant shall neither assert nor seek to enforce any claim against
Landlord, or Landlord's agents or employees, or the assets of Landlord or of
Landlord's agents or employees, for breach of this Lease or otherwise, other
than against Landlord's interest in the Park and in the uncollected rents,
issues and profits thereof, and Tenant agrees to look solely to such interest
for the satisfaction of any liability of Landlord under this Lease, it being
specifically agreed that in no event shall Landlord or Landlord's agents or
employees (or any of the officers, trustees, directors, partners, beneficiaries,
joint venturers, members, stockholders or other principals or representatives,
and the like, disclosed or undisclosed, thereof) ever be personally liable for
any such liability. This

                                      53
<PAGE>

paragraph shall not limit any right that Tenant might otherwise have to obtain
injunctive relief against Landlord or to take any other action which shall not
involve the personal liability of Landlord to respond in monetary damages from
Landlord's assets other than the Landlord's interest in said real estate, as
aforesaid. In no event shall Landlord or Landlord's agents or employees (or any
of the officers, trustees, directors, partners, beneficiaries, joint venturers,
members, stockholders or other principals or representatives and the like,
disclosed or undisclosed, thereof) ever be liable for consequential or
incidental damages. If by reason of Landlord's failure to complete Landlord's
Work, Landlord shall be held to be in breach of this Lease, Tenant's sole and
exclusive remedy shall be to terminate the Lease in accordance with Article 4.1.

27.      BILLS AND NOTICES

         Any notice, consent, request, bill, demand or statement hereunder by
either party to the other party shall be in writing and, if received at
Landlord's or Tenant's address, shall be deemed to have been duly given when
either served personally and by certified mail, return receipt requested,
deposited in the United States mail, or sent by recognized overnight courier
service addressed to Landlord at its address as stated in Exhibit 1 and to
Tenant at the Premises (or at Tenant's address as stated in Exhibit 1, if mailed
prior to Tenant's occupancy of the Premises) with a coy to Glen M. Mair, Esq.,
Mirick O'Connell, DeMallie & Lougee, LLP, 100 Front Street, Worcester, MA
01608-1477, or if any address for notices shall have been duly changed as
hereinafter provided, if mailed as aforesaid to the party at such changed
address. Either party may at any time change the address or specify an
additional address for such notices, consents, requests, bills, demands or
statements by delivering or mailing, as aforesaid, to the other party a notice
stating the change and setting forth the changed or additional address, provided
such changed or additional address is within the United States.

         If Tenant's interest in the Lease is assigned to a partnership, Tenant,
for itself, and on behalf of all of its partners, shall appoint a partner of
Tenant as Tenant's Service Partner, to accept service of any notice, consent,
request, bill, demand or statement hereunder by Landlord and any service of
process in any judicial proceeding with respect to this Lease on behalf of
Tenant and as agent and attorney-in-fact for each partner of Tenant.

         All bills and statements for reimbursement or other payments or charges
due from Tenant to Landlord hereunder shall be due and payable in full thirty
(30) days from receipt of the same by Tenant, unless herein otherwise provided.
Tenant's failure to make timely payment of any amounts indicated by such bills
and statements, whether for work done by Landlord at Tenant's request,
reimbursement provided for by this Lease or for any other sums properly owing by
Tenant to Landlord, shall be treated as a default in the payment of rent, in
which event Landlord shall have all rights and remedies provided in this Lease
for the nonpayment of rent.

                                      54
<PAGE>

28.      PARTIES BOUND -- SEIZING OF TITLE

         The covenants, agreements, terms, provisions and conditions of this
Lease shall bind and benefit the successors and assigns of the parties hereto
with the same effect as if mentioned in each instance where a party hereto is
named or referred to, except that no violation of the provisions of Article 16
hereof shall operate to vest any rights in any successor or assignee of Tenant
and that the provisions of this Article 28 shall not be construed as modifying
the conditions of limitation contained in Article 21 hereof.

         If, in connection with or as a consequence of the sale, transfer or
other disposition of the real estate (land and/or Building, either or both, as
the case may be) of which the Premises are a part, Landlord ceases to be the
owner of the reversionary interest in the Premises, Landlord shall be entirely
freed and relieved from the performance and observance from and after the date
of such sale, transfer or other disposition of all covenants and obligations
hereunder on the part of Landlord to be performed and observed, provided that in
such event (and it shall be deemed and construed as a covenant running with the
land) the person succeeding to Landlord's ownership of said reversionary
interest shall thereupon assume, and perform and observe, any and all of such
covenants and obligations of Landlord.

29.      MISCELLANEOUS

         29.1  Separability. If any provision of this Lease or portion of such
provision or the application thereof to any person or circumstance is for any
reason held invalid or unenforceable, the remainder of the Lease (or the
remainder of such provision) and the application thereof to other persons or
circumstances shall not be affected thereby.

         29.2  Captions, etc. The captions are inserted only as a matter of
convenience and for reference, and in no way define, limit or describe the scope
of this Lease nor the intent of any provisions thereof. References to "State"
shall mean, where appropriate, the District of Columbia and other Federal
territories, possessions, as well as a state of the United States.

         29.3     Broker.

         (a) Tenant represents and warrants that it has not directly or
indirectly dealt, with respect to the leasing of space in the Building or the
Park (called "Building, etc." in this Article 29.3) with any broker or had its
attention called to the Premises or other space to let in the Building, etc. by
anyone other than the broker, person or firm, if any, designated in Exhibit 1.
Tenant agrees to defend, exonerate and save harmless and indemnify Landlord and
anyone claiming by, through or under Landlord against any claims for a
commission arising in breach of the representation and warranty set forth in the
immediately preceding sentence, provided that Landlord shall be solely
responsible for the payment of brokerage commissions to the broker, person or
firm, if any, designated in Exhibit 1.

                                      55
<PAGE>

         (b)   Landlord represents and warrants that, in connection with the
execution and delivery of the Lease, it has not directly or indirectly dealt
with any broker other than the brokers designated on Exhibit 1. Landlord agrees
to defend, exonerate, save harmless, and indemnify Tenant and anyone claiming
by, through, or under Tenant against any claims arising in breach of the
representation and warranty set forth in the immediately preceding sentence.

         29.4  Governing Law. This Lease is made pursuant to, and shall be
governed by, and construed in accordance with, the laws of the State wherein the
Building is situated and any applicable local municipal rules, regulations,
by-laws, ordinances and the like.

         29.5  Assignment of Rents. With reference to any assignment by Landlord
of its interest in this Lease, or the rents payable hereunder, conditional in
nature or otherwise, which assignment is made to or held by a bank, trust
company, insurance company or other institutional lender holding a mortgage or
ground lease on the Building, Tenant agrees:

         (a)   that the execution thereof by Landlord and the acceptance thereof
by such mortgagee and/or ground lessor shall never be deemed an assumption by
such mortgagee and/or ground lessor of any of the obligations of the Landlord
thereunder, unless such mortgagee and/or ground lessor shall, by written notice
sent to the Tenant, specifically otherwise elect; and

         (b)   that, except as aforesaid, such mortgagee and/or ground lessor
shall be treated as having assumed the Landlord's obligations thereunder only
upon foreclosure of such mortgagee's mortgage or deed of trust or termination of
such ground lessor's ground lease and the taking of possession of the Premises
after having given notice of its exercise of the option stated in Article 23
hereof to succeed to the interest of the Landlord under this Lease.

         29.6  Representation of Authority. By his execution hereof each of the
signatories on behalf of the respective parties hereby warrants and represents
to the other that he is duly authorized to execute this Lease on behalf of such
party. Landlord hereby represents to Tenant that it is the owner of the fee
interest of the Building.

         29.7  Expenses Incurred by Landlord Upon Tenant Requests. Tenant shall,
upon demand, reimburse Landlord for all reasonable expenses, including, without
limitation, legal fees, incurred by Landlord in connection with all requests by
Tenant for consents, approvals or execution of collateral documentation related
to this Lease, including, without limitation, costs incurred by Landlord in the
review and approval of Tenant's plans and specifications in connection with
proposed alterations to be made by Tenant to the Premises, requests by Tenant to
sublet the Premises or assign its interest in the Lease, the execution by
Landlord of estoppel certificates requested by Tenant, and requests by Tenant
for Landlord to execute waivers of Landlord's interest in Tenant's

                                      56
<PAGE>

property in connection with third party financing by Tenant. Such costs shall be
deemed to be additional rent under the Lease.

         29.8  Survival. Without limiting any other obligation of Tenant or
Landlord which may survive the expiration or prior termination of the term of
the Lease, all obligations on the part of each party to indemnify, defend, or
hold the other party harmless, as set forth in this Lease shall survive the
expiration or prior termination of the term of the Lease.

         IN WITNESS WHEREOF the parties hereto have executed this Indenture of
Lease in multiple copies, each to be considered an original hereof, as a sealed
instrument on the day and year noted in Exhibit 1 as the Execution Date.

LANDLORD:                               TENANT:
EOP-CROSBY CORPORATE CENTER, L.L.C.     VIALOG CORPORATION


By:  EOP Operating Limited
     Partnership, a Delaware
     limited partnership, its
     sole member

     By:    Equity Office
            Properties Trust,
            a Maryland real
            estate investment
            trust, its managing
            general partner

     By:    /s/ Thomas Q. Bakke      By:  /s/ John J. Dion
            --------------------          ----------------
     Name:  Thomas Q. Bakke          (Name)
            ------------------       Vice President - Finance & Treasurer
     Title: Vice President           Hereunto Duly Authorized


          A SECRETARY'S OR CLERK'S CERTIFICATE OF THE AUTHORITY AND THE
INCUMBENCY OF THE PERSON SIGNING ON BEHALF OF TENANT AND LANDLORD SHOULD BE
ATTACHED.
<PAGE>

                               EXHIBIT 1, SHEET 1
                                 Building No. 7
                             CROSBY CORPORATE CENTER
                             Bedford, Massachusetts


--------------------- ----------------------------------------------------------
Execution             March 3, 2000
Date:
--------------------- ----------------------------------------------------------
Tenant:               Vialog Corporation, a Massachusetts corporation
--------------------- ----------------------------------------------------------
Tenant's              35 New England Business Center,
Mailing
Address:              Andover, MA  01810

--------------------- ----------------------------------------------------------
Landlord:             EOP-Crosby Corporate Center, L.L.C., a Delaware limited
                      liability company (the sole member of which is EOP
                      Operating Limited Partnership, a Delaware Limited
                      Partnership; the managing general partner of which is
                      Equity Office Properties Trust, a Maryland real estate
                      investment trust).
--------------------- ----------------------------------------------------------
Landlord's            1111 19th Street NW, Washington, D.C. 20036
Mailing
Address:              with a copy to:

                      EOP-Crosby Corporate Center, L.L.C., c/o Equity Office
                      Properties Trust, Two North Riverside Plaza, Suite 2200,
                      Chicago, IL  60606, Attn:  General Counsel of Property
                      Operations
--------------------- ----------------------------------------------------------
Park:                 The land, buildings and other improvements thereon, from
                      time to time, located off Crosby Drive in the Town of
                      Bedford, Middlesex County, Commonwealth of Massachusetts
                      known as Crosby Corporate Center. The Park is
                      substantially as shown on Exhibit 3, Sheet 1, and the
                      legal description of the Park is set forth on Exhibit 3,
                      Sheets 2, 3 and 4. The Park includes Phase II which is
                      substantially as shown on Exhibit 3, Sheet 1 and the legal
                      description of the Park is set forth on Exhibit 3, Sheet
                      4.
--------------------- ----------------------------------------------------------
Building:             32 Crosby Drive, Bedford, Massachusetts (Building Seven in
                      the Park). The Building is located in Phase II of the
                      Park.
--------------------- ----------------------------------------------------------
Premises:             An area on the first (1st) floor of the Building,
                      --------------------------------------------------
                      substantially as shown on Lease Plan, Exhibit 2.
                      ------------------------------------------------
--------------------- ----------------------------------------------------------
Art. 3.1              Specified Commencement Date: May 15, 2000
                                                   ------------
--------------------- ----------------------------------------------------------
Art. 3.2              Termination Date:            Five (5) years after the term
                                                   -----------------------------
                                                   Commencement Date
                                                   ------------------
--------------------- ----------------------------------------------------------
Art. 4                Final Plans Date:            March 15, 2000
                                                   --------------
--------------------- ----------------------------------------------------------

                                      -1-

<PAGE>

                               EXHIBIT 1, SHEET 2
                                 Building No. 7
                             CROSBY CORPORATE CENTER
                             Bedford, Massachusetts

                           Tenant: Vialog Corporation
                          Execution Date: March 3, 2000
--------------------------------------------------------------------------------
Art. 5                          Use of Premises:  General business offices,
                                                  -------------------------
                                                  assembly and manufacturing and
                                                  ------------------------------
                                                  research and development.
                                                  -------------------------

--------------------------------------------------------------------------------
Art. 6                          Yearly Rent:
--------------------------------------------------------------------------------
Lease Year1          Yearly Rent         Monthly Payment         Per Square Foot
--------------------------------------------------------------------------------
    1-3              $668,832.00           $55,736.00                   $24.00
--------------------------------------------------------------------------------
    4-5              $696,700.08           $55,058.34                   $25.00
--------------------------------------------------------------------------------
Art. 6.3                Total Rentable Area

                        Premises: 27,868 square feet
                                  ------
                        Building 7: 103,717 square feet
                                    -------
                        Phase II of the Park: 257,528 square feet
                                              -------
                        The Park: 594,129 square feet
                                  -------
--------------------------------------------------------------------------------
Art. 8                  Electricity: Electric current will be sub-metered
                        -------------------------------------------------
                        and paid for by Tenant in accordance with Article
                        -------------------------------------------------
                        8.1 of the Lease.
                        -----------------
--------------------------------------------------------------------------------
Art. 9                Operating and Tax Escalation:

                          Operating Expense Excess:

                          Tenant's Operating Cost Percentage:  26.8693%
                                                                --------

                          Operating Costs in the Base Year: The actual amount
                                                            -----------------
                                                            of Operating costs
                                                            ------------------
                                                            in calendar
                                                            -----------
                                                            Year 2000
                                                            ---------
                          Tax Excess:

                             Tenant's Tax Percentage: 10.8213%
                                                      -------

                             Tax Base: The actual amount of Taxes for
                                       ------------------------------
                                       fiscal/tax year 2001 (i.e. July 1, 2000 -
                                       -----------------------------------------
                                       June 30, 2001
                                       -------------
--------------------------------------------------------------------------------

-------------------

1     For purpose of this Lease, "Lease Year" shall be defined as any
      twelve-(12)-Month period during the term of the Lease Commencement Date or
      as of any anniversary of the Term Commencement Date.

                                      -2-
<PAGE>

                               EXHIBIT 1, SHEET 3
                                 Building No. 7
                             CROSBY CORPORATE CENTER
                             Bedford, Massachusetts

                           Tenant: Vialog Corporation
                          Execution Date: March 3, 2000

Art. 29.3       Broker:  Meredith & Grew, Inc.
                         ---------------------

LANDLORD;

EOP-CROSBY CORPORATE CENTER, L.L.C.

By:   EOP Operating Limited Partnership, a Delaware limited partnership, its
      sole member

      By:   Equity Office Properties Trust, a Maryland real estate investment
            trust, its managing general partner
            By: /s/ THOMAS Q. BAKKE
               ---------------------
               (Name)(Title) THOMAS Q. BAKKE
                             VICE PRESIDENT

Date Signed: 3/3
            -----

TENANT;
VIALOG CORPORATION

By: /s/ John J. Dion
   -----------------
   (Name) John J. Dion
   (Title) Vice President-Finance & Treasurer
   Hereunto Duly Authorized

Dated Signed: 2/18/00
             --------

                                      -3-
<PAGE>

                                   EXHIBIT 2
                                   ---------
                                  LEASE PLAN
                                  ----------

      This Exhibit is attached to and made a part of the Lease dated as of     ,
2000, by and between EOP- Crosby Corporate Center, L.L.C. ("Landlord") and
Vialog Corporation ("Tenant") for space in the Building located at Building 7,
Crosby Corporate Center, Bedford, Massachusetts.

                    [Exhibit contains graphic of floor plan.]

                                      -1-
<PAGE>

                                    EXHIBIT 3
                                    ---------
                       PLAN AND LEGAL DESCRIPTION OF PARK
                       -----------------------------------

[Exhibit contains maps of Crosby Corporate Center Complex and legal description]

                                      -2-
<PAGE>

                                    EXHIBIT 4
                                    ---------
                            ENVIRONMENTAL DISCLOSURE
                            ------------------------

                       EXISTING SITE CONDITIONS -- PHASE I
                       -----------------------------------

Landlord represents to Tenant that, as of the Execution Date of the Lease,
Landlord is aware of the site conditions disclosed in the following
documentation:

      Draft Tank Removal Observation Reports prepared for Digital Equipment
            Corporation ("Digital") by GZA GeoEnvironmental, Inc. ("GZA")
            undated and unsigned.

      Release Categorization Form submitted by GZA on behalf of Digital to the
            Massachusetts Department of Environmental Protection ("DEP") undated
            and unsigned;

      Report on Preliminary Oil and Hazardous Material Site Evaluation dated
            August 18, 1992 prepared by Haley & Aldrich, Inc. for Rubin and
            Rudman;

      Draft Report dated May 26, 1992 from GZA to Digital, Re: Additional
            Environmental Study, Former Crosby Drive Facility unsigned;

      Letter dated February 3, 1993 to Digital from DEP captioned "BEDFORD -- 12
            CROSBY DRIVE, Former Digital Corp. Site, DEP Case #3-4264, NOTICE OF
            RESPONSIBILITY PURSUANT TO M.G.L. C.21E and Phase I Request";

      Preliminary Site Assessment Update and Limited Subsurface Investigation
            dated April 23, 1993 prepared by Rizzo Associates, Inc., for C & K
            Components, Inc.;

      Waiver Application Form, Preliminary Assessment Report, Interim Site
            Classification Form, and Phase I Limited Site Investigation, 12
            Crosby Drive, Bedford, Massachusetts, DEP Site No. 3-4624, each
            prepared by GZA;

      Investigative Survey Report for Asbestos-Containing Materials, Bedford
            Research Park, 30 Crosby Drive, Bedford, MA 01730 dated October 7,
            1992 prepared for Bedford Research Park Associates by H +GCL, Inc.;

      Regulatory File Review, Bedford Research Park, 30 Crosby Drive, Bedford,
            Massachusetts, dated April 12, 1994 prepared by Haley & Aldrich,
            Inc.; and

      Report on Oil and Hazardous Material Site Evaluation, Bedford Research
            Park, 12 to 30 Crosby Drive, Bedford, Massachusetts prepared by
            Haley & Aldrich, Inc. dated April 24, 1994, Revised May 2, 1994.

                                      -3-
<PAGE>

                      EXISTING SITE CONDITIONS -- PHASE II
                      ------------------------------------

      "TANK REMOVAL OBSERVATION, DIGITAL EQUIPMENT CORPORATION, CROSBY DRIVE,
            BEDFORD, MA," MARCH 1992.

      "ADDITIONAL ENVIRONMENTAL STUDY, FORMER CROSBY DRIVE FACILITY, BEDFORD,
            MA," DECEMBER 1992.

      "PHASE I LIMITED SITE INVESTIGATION, 12 CROSBY DRIVE, BEDFORD, MA DEP SITE
            NO. 3-4264," JULY 1993.

      "PHRASE II COMPREHENSIVE SITE ASSESSMENT SCOPE OF WORK, GASOLINE UST AREA,
            FORMER DIGITAL FACILITY, BEDFORD, MA DEP SITE NO. 3-4264, WAIVER
            SUBMITTAL," SEPTEMBER 1995.

"PHASE II COMPREHENSIVE SITE ASSESSMENT FORMER DIGITAL BEDFORD FACILITY,
      BEDFORD, MA RELEASE TRACKING NUMBER 3-4264, WAIVER SUBMITTAL," APRIL 1996.

                                      -4-
<PAGE>

                                    EXHIBIT 5
                                    ---------
                                BUILDING SERVICES
                                -----------------

A.    General Cleaning (Monday through Friday)

      1.    All stone, ceramic, tile, marble, terrazzo and other unwaxed
            flooring to be swept nightly, using approved dust-down preparation.

      2.    All wood, linoleum, vinyl-asbestos, vinyl and other similar types of
            floors to be swept or dry mopped nightly, using dust-down
            preparation; all carpeting and rugs in the main traffic areas
            (corridors, reception areas, etc.) to be vacuumed nightly and all
            other carpeted areas to be vacuumed at least once each week.

      3.    Wax all public areas monthly.

      4.    Hand dust all furniture, files and fixtures nightly.

      5.    Empty all waste receptacles nightly and remove waste paper and waste
            materials, including folded paper boxes and cartons, to a designated
            area.

      6.    Empty and clean all ash trays and screen all sand urns nightly.

      7.    Wash and clean all water fountains and coolers nightly. Sinks and
            floors adjacent to sinks to be washed nightly.

      8.    Hand dust all door and other ventilating louvers within reach, as
            necessary, but not less often than monthly.

      9.    Dust all telephones as necessary.

      10.   Keep lockers and janitor sink rooms in a neat, orderly condition at
            all times.

      11.   Wipe clean all bright metal work as necessary.

      12.   Check all stairwells throughout entire building nightly and keep in
            clean condition.

      13.   Metal doors and trim of all public elevator cars to be properly
            maintained and kept clean.

B.    Common Area Lavatories

      1.    Sweep and wash all lavatory floors nightly, using proper non-scented
            disinfectants.

                                      -5-
<PAGE>

      2.    Clean all mirrors, powder shelves, bright work and enameled surfaces
            in all lavatories nightly. Scour, wash and disinfect all basins,
            bowls and urinals using non-scented disinfectants.

      3.    Police lavatories during the day with matron or porter to pick up
            waste and replenish materials.

      4.    Wash all toilet seats nightly.

      5.    Fill toilet tissue holders nightly.

      6.    Empty paper towel receptacles nightly.

      7.    Empty sanitary disposal receptacles nightly.

      8.    Thoroughly clean all wall tile and stall surfaces as necessary.

C.    High Dusting

      Do all high dusting (not reached in nightly cleaning) quarterly which
      includes the following:

      1.    Dust all pictures, frames, charts, graphs, and similar wall
            hangings.

      2.    Dust exposed pipes, ventilation and air conditioning louvers, ducts
            and high moldings.

D.    Window Cleaning

      1.    All exterior windows (except for any retail/commercial areas) from
            the second floor and above will be cleaned inside and outside except
            when cleaning is rendered impracticable by inclement weather.

      2.    Entrance doors and elevator lobby glass to be cleaned daily and kept
            in a clean condition at all times during the day.

      3.    Wipe down all metal window frames as necessary but not less often
            than monthly.

E.    Building Lobbies

      1.    Floors to be swept and washed or vacuumed nightly, and machine
            scrubbed according to Building Standard frequency.

                                      -6-
<PAGE>

      2.    Carpeting in passenger elevator cabs to be vacuum cleaned nightly.

      3.    Lobby walls to be dusted as often as necessary, but not less than
            weekly.

      4.    Screen and clean sand urns nightly.

      5.    Clean all unpainted metal work in a manner appropriate to original
            finish.

F.    Porters

      Necessary number of day porters under supervision will be assigned for the
      following services:

      1.    Service all public and building operating space throughout the
            Building.

      2.    Keep elevator cars clean and neat during the day.

      3.    Maintain lobbies clean and, during wet weather, mopped dry to the
            extent practicable.

      4.    Dust and rub down all elevator doors, frames, telephone booths and
            directories daily.

      5.    Sweep sidewalks, ramps, etc. daily.

      6.    Clean roofs and setbacks as often as necessary.

      7.    Maintain firehose and equipment clean.

      8.    Lay and remove lobby runners as necessary.

      9.    Replenish toilet tissue, towels and other supplies in lavatories.

      10.   Maintain fan rooms, motor rooms and air conditioning rooms in clean
            condition.

      11.   Check stairways and keep same neat and clean during the day.

      12.   Clean exterior columns, exterior signs and metal work, standpipe and
            sprinkler system, walkways and stairs as necessary.

      13.   If directed by superintendent, fill towel and soap dispensers and
            perform any emergency cleaning required.

                                      -7-
<PAGE>

                                    EXHIBIT 6
                             SAMPLE LETTER OF CREDIT
                            ------------------------
                         [Name of Financial Institution]

                                                  Irrevocable Standby
                                                  Letter of Credit
                                                  No. ______________________
                                                  Issuance Date:_____________
                                                  Expiration Date:____________
                                                  Applicant:  Vialog Corporation



Beneficiary
-----------

EOP-Crosby Corporate Center, L.L.C.
1111  19th Street, N.W.
Washington, D.C.  20036

Ladies/Gentlemen:

      We hereby establish our Irrevocable Standby Letter of Credit in your favor
for the account of the above referenced Applicant in the amount of
____________________ U.S. Dollars ($____________________) available for payment
at sight by your draft drawn on us when accompanied by the following documents:

1.    An original copy of this Irrevocable Standby Letter of Credit.

2.    Beneficiary's dated statement purportedly signed by one of its officers
      reading: "This draw in the amount of ______________________ U.S. Dollars
      ($____________) under your Irrevocable Standby Letter of Credit No.
      ____________________ represents funds due and owing to us as a result of
      the Applicant's failure to comply with one or more of the terms of that
      certain lease by and between EOP-Crosby Corporate Center, L.L.C., as
      landlord, and Vialog Corporation, as tenant."

      It is a condition of this Irrevocable Standby Letter of Credit that it
will be considered automatically renewed for a one year period upon the
expiration date set forth above and upon each anniversary of such date, unless
at least sixty (60) days prior to such expiration date or applicable anniversary
thereof, we notify you in writing by certified mail, return receipt requested,
that we elect not to so renew this Irrevocable Standby Letter of Credit. A copy
of any such notice shall also be sent to: Equity Office Properties Trust, 2
North Riverside Plaza, Suite 2200, Chicago, IL 60606, Attention: Vice
President-Corporate Operations. In addition to the foregoing, we understand and
agree that you shall be entitled to draw upon this Irrevocable Standby Letter of
Credit in accordance with 1 and 2 above in
<PAGE>

the event that we elect not to renew this Irrevocable Standby Letter of Credit
and, in addition, you provide us with a dated statement purportedly signed by
one of Beneficiary's officers stating that the Applicant has failed to provide
you with an acceptable substitute irrevocable standby letter of credit in
accordance with the terms of the above referenced lease. We further acknowledge
and agree that: (a) upon receipt of the documentation required herein, we will
honor your draws against this Irrevocable Standby Letter of Credit without
inquiry into the accuracy of Beneficiary's signed statement and regardless of
whether Applicant disputes the content of such statement; (b) this Irrevocable
Standby Letter of Credit shall permit partial draws and, in the event you elect
to draw upon less than the full stated amount hereof, the stated amount of this
Irrevocable Standby Letter of Credit shall be automatically reduced by the
amount of such partial draw; and (c) you shall be entitled to assign your
interest in this Irrevocable Standby Letter of Credit from time to time without
our approval and without charge. In the event of an assignment, we reserve the
right to require reasonable evidence of such assignment as a condition to any
draw hereunder.

      This Irrevocable Standby Letter of Credit is subject to the Uniform
Customs and Practice for Documentary Credits (1993 revision) ICC Publication No.
500.

      We hereby engage with you to honor drafts and documents drawn under and in
compliance with the terms of this Irrevocable Standby Letter of Credit.

      All communications to us with respect to this Irrevocable Standby Letter
of Credit must be addressed to our office located at
______________________________ to the attention of
__________________________________.

                                                   Very truly yours,

                                                   ----------------------

                                                          [name]
                                                   --------------------

                                                          [title}
<PAGE>

                                      RIDER
                                      -----

      This Rider is attached to and made a part of the Lease and is entered into
as of the day of   , 2000 by and between EOP-CROSBY CORPORATE CENTER, L.L.C., a
Delaware limited liability company ("Landlord") and VIALOG CORPORATION, a
Massachusetts corporation ("Tenant") for space in the Building located at 32
Crosby Drive, Bedford, Massachusetts (Building Seven in the Park).

1.    TENANT'S OPTION TO EXTEND THE TERM OF THE LEASE
      -----------------------------------------------

      A.    Tenant, provided it is not in default and has not sublet more than
25% of the Premises or assigned this Lease, shall have the right to extend the
term of the Lease for one additional period of five (5) years commencing on the
day following the expiration of the initial term of the Lease ("Termination
Date") and ending on the fifth (5th) anniversary of the Termination Date (the
"Renewal Term"). Such option to extend the term of the Lease shall be exercised
by providing written notice ("Exercise Notice") to Landlord on or before the
date nine (9) months prior to the Termination Date of the initial term of the
Lease.

      B.    The Yearly Rent during the Renewal Term shall equal the prevailing
market rate for such space as determined in Landlord's reasonable judgment.
Within 30 days after receipt of Tenant's Exercise Notice, Landlord shall advise
Tenant of Landlord's designation of the Yearly Rent during the Renewal Term.
Tenant shall have the right, by written notice ("Arbitration Notice") given to
Landlord within 15 days after the date on which Landlord advises Tenant of
Landlord's designation, to submit such designation to appraisal in accordance
with the procedures set forth in Subparagraph E of this Paragraph 1. If Tenant
fails timely to give Landlord an Arbitration Notice, then Landlord's designation
of the applicable Yearly Rent for the Renewal Term shall be final and binding on
Landlord and Tenant.

      C.    Tenant shall pay Operating Expense Excess and Tax Excess during the
Renewal Term in accordance with the terms of this Lease.

      D.    If Tenant is entitled to and properly exercises the renewal option,
Landlord shall prepare an amendment (the "Renewal Amendment") to reflect changes
in the Yearly Rent, term of Lease, Termination Date and other appropriate terms.
The Renewal Amendment shall be:

      1.    sent to Tenant within 60 days after receipt of the Renewal Notice;
            and

      2.    executed by Tenant and returned to Landlord within 15 days of
            receipt thereof.

      E.    If Tenant provides Landlord with an Arbitration Notice, each party
shall, at its own expense, select and retain an appraiser, with the
qualifications set forth below and notify the other party of its selection
within ten (10) days after Landlord's receipt of
<PAGE>

the Arbitration Notice. Each appraiser so selected shall be certified as an MAI
appraiser or as an ASA appraiser and shall have had at least three (3) years
experience within the previous ten (10) years as a real estate appraiser working
in the Bedford, Massachusetts area, with working knowledge of current rental
rates and practices. For purposes of this Lease, an "MAI" appraiser means an
individual who holds an MAI designation conferred by, and is an independent
member of, the American Institute of Real Estate Appraisers (or its successor
organization, or in the event there is no successor organization, the
organization and designation most similar), and an "ASA" appraiser means an
individual who holds the Senior Member designation conferred by, and is an
independent member of, the American Society of Appraisers (or its successor
organization, or, in the event there is no successor organization, the
organization and designation most similar). Within thirty (30) days after
Landlord's receipt of the Arbitration Notice, each appraiser shall determine the
prevailing market rate and shall notify the other appraiser and both parties of
such appraiser's determination. In the event only one party selects an appraiser
and notifies the other party of its selection during the ten (10) day period
specified above, and such party's appraiser gives such notice within the thirty
(30) day period, or in the event an appraiser duly selected by one party fails
to give such notice within the thirty (30) day period, then the determination of
the prevailing market rate made by the selected appraiser who gave such notice
shall be deemed to be the prevailing market rate. If the determination of the
appraisers are within five percent (5%) of each other, the prevailing market
rate shall be the average of the two (2) determinations. If both appraisers
notify each other and both of the parties of their respective determination of
the prevailing market rate within the thirty (30) day period, and their
determinations do not agree within five percent (5%) on the prevailing market
rate, then within fifteen (15) days after both appraisers notify both parties of
their respective determination of the prevailing market rate, each party will
cause the appraiser selected by it to confer with the other appraiser and the
two (2) appraisers shall select a third appraiser (the "Third Appraiser") having
the qualifications set forth above. In the event the appraisers selected by
Landlord and Tenant cannot agree upon the Third Appraiser within such fifteen
(15) day period, each party will, within ten (10) days thereafter, cause the
appraiser selected by it to supply the name of one (1) appraiser having the
qualifications as set forth above, and a representative of Landlord, with a
representative of Tenant present, shall make a blind draw of one (1) name of the
two (2) provided who shall serve as the Third Appraiser. In the event only one
of the appraisers supplies the name of a prospective third appraiser during such
ten (10) day period, the appraiser named by such appraiser shall be the Third
Appraiser. Within twenty (20) days from the date of his appointment, the Third
Appraiser shall make his determination of the prevailing market rate for the
Renewal Term and will submit a written determination thereof to both parties and
both appraisers. Within a fifteen (15) day period after delivery of the Third
Appraiser's determination of the prevailing market rate, the three (3)
appraisers shall confer and attempt to reach agreement as to the prevailing
market rate. In the event the three (3) appraisers cannot within the fifteen
(15) day conference period reach a determination of the prevailing market rate,
then the determination of any two (2) of the three (3) appraisers shall be
deemed to be the prevailing market rate for the Renewal Term. If the Third
Appraiser fails to make his determination within the twenty (20) day period, or
if two (2) appraisers cannot agree within the fifteen (15) day conference
period, the parties shall repeat the
<PAGE>

selection procedure hereinabove described and shall thereby choose a new Third
Appraiser. If the Third Appraiser believes that expert advice would materially
assist him, he may retain one or more qualified persons, to provide such expert
advice. The parties shall share equally in the costs of the Third Appraiser and
of any experts retained by the Third Appraiser. Any fees of any appraiser,
counsel or experts engaged directly by Landlord or Tenant, however, shall be
borne by the party retaining such appraiser, counsel or expert. In the event
that the prevailing market rate has not been determined by the commencement date
of the Renewal Term, Tenant shall pay Yearly Rent upon the terms and conditions
in effect for initial Premises until such time as the prevailing market rate has
been determined. Upon such determination, the Yearly Rent shall be retroactively
adjusted to the commencement of the Renewal Term. If such adjustment results in
an underpayment of Yearly Rent by Tenant, Tenant shall pay Landlord the amount
of such underpayment within thirty (30) days after the determination thereof. If
such adjustment results in an overpayment of Yearly Rent by Tenant, Landlord
shall credit such overpayment against the next installment of Yearly Rent due
under the Lease and, to the extent necessary, any subsequent installments until
the entire amount of such overpayment has been credited against Base Rent.

2.    SECURITY DEPOSIT
      ----------------

      A.   A Security Deposit in the amount of $350,000.00 shall be delivered to
Landlord upon execution of this Lease by Tenant and shall be held by Landlord
without liability for interest (except as required by law) and as security for
the performance of Tenant's obligations under this Lease. The Security Deposit
shall not be considered an advance payment of Rent or a measure of Tenant's
liability for damages. Landlord may, from time to time, without prejudice to any
other remedy, use all or a portion of the Security Deposit to make good any
arrearage of Rent, to repair damages to the Premises, to clean the Premises upon
termination of this Lease or otherwise to satisfy any other covenant or
obligation of Tenant hereunder. In addition, in the event of a termination based
upon the default of Tenant under the Lease, or a rejection of the Lease pursuant
to the provisions of the Federal Bankruptcy Code, Landlord shall have the right
to use all or a portion of the Security Deposit (from time to time, if
necessary) to cover the full amount of damages and other amounts due from Tenant
to Landlord under the Lease. Any amounts so used shall, at Landlord's election,
be applied first to any unpaid rent and other charges which were due prior to
the filing of the petition for protection under the Federal Bankruptcy Code.
Following any such application of the Security Deposit, Tenant shall pay to
Landlord on demand the amount so applied in order to restore the Security
Deposit to its original amount. If Tenant is not in default at the termination
of this Lease, after Tenant surrenders the Premises to Landlord in accordance
with this Lease and all amounts due Landlord from Tenant are finally determined
and paid by Tenant or through application of the Security Deposit, the balance
of the Security Deposit remaining after any such application shall be returned
to Tenant. If Landlord transfers its interest in the Premises during the Lease
Term, Landlord shall assign the Security Deposit to the transferee and
thereafter shall have no further liability for the return of such Security
Deposit. Tenant agrees to look solely to such transferee or assignee for the
return of the Security Deposit. Landlord and its successors and assigns shall
not be
<PAGE>

bound by any actual or attempted assignment or encumbrance of the Security
Deposit by Tenant, provided, however, if Tenant's interest in this Lease has
been assigned, Landlord shall, provided that Landlord has been furnished with a
fully executed copy of the agreement assigning such Security Deposit, return the
Security Deposit to such assignee in accordance with the terms and conditions
hereof. If Landlord returns the Security Deposit to Tenant's assignee as
aforesaid, Landlord will have no further obligation to any party with respect
thereto. Landlord shall not be required to keep the Security Deposit separate
from its other accounts.

      B.    All or part of the Security Deposit may be in the form of an
irrevocable letter of credit (the "Letter of Credit"), which Letter of Credit
shall: (a) be issued on the form attached hereto as Exhibit 6, attached hereto
and incorporated by reference herein; (b) name the Landlord as its beneficiary;
(c) be drawn on an FDIC insured financial institution satisfactory to the
Landlord; and (d) expire no earlier than sixty (60) days after the Termination
Date of this Lease.

      C.    Notwithstanding anything herein to the contrary, provided that (i)
Tenant is not in default under this Lease as of the effective date of the
reduction of the Security Deposit or as of the date Landlord is required to
return such portion of the Security Deposit and (ii) Tenant submits to Landlord,
at least 30 days prior to the Effective Reduction Date, as hereinafter defined,
audited financial statements indicating to Landlord's reasonable satisfaction
that the 12 month period immediately preceding the Effective Reduction Date were
profitable, as determined in accordance with generally accepted accounting
principles, Tenant shall have the right to reduce the amount of the Security
Deposit to $150,000.00 effective as of the third (3rd) anniversary of the Term
Commencement Date ("Effective Reduction Date"). If Tenant is entitled to a
reduction in the Security Deposit, Tenant shall have the right to provide
Landlord with written notice requesting that the Security Deposit be reduced as
provided above (the "Reduction Notice"). If Tenant provides Landlord with a
Reduction Notice, Landlord shall refund the applicable portion of the Security
Deposit to Tenant within forty-five (45) days after the later to occur of (i)
Landlord's receipt of the Reduction Notice, or (ii) the date upon which Tenant
is entitled to a reduction in the Security Deposit as provided above.

3.    ANTENNA AREA
      ------------

      Tenant shall have the right to use the Antenna Area, as hereinafter
defined, to install a satellite dish and/or antenna (collectively, the
"Antenna") for a period commencing as of the date that Tenant installs the
Antenna, as hereinafter defined, in the Antenna Area ("Commencement Date in
respect of the Antenna Area") and terminating as of the expiration or earlier
termination of the Term of the Lease. The "Antenna Area" shall be an area on the
roof of the Building in a location to be designated by Landlord. Tenant shall be
permitted to use the Antenna Area solely for one (1) Antenna installed in
accordance with specifications approved by Landlord in advance utilizing a
frequency or frequencies and transmission power identified in such approved
specifications and no other frequencies or transmission power shall be used by
Tenant without Landlord's prior written consent. Such installation shall be
designed in such manner as to be easily
<PAGE>

removable and so as not to damage the roof of the Building. The Antenna and any
replacement shall be subject to Landlord's approval. Tenant's use of the Antenna
Area shall be upon all of the conditions of the Lease, except as follows:

      A.   Tenant shall have no obligation to pay Yearly Rent, Operating Expense
Excess or Tax Excess in respect of the Antenna Area.

      B.   Landlord shall have no obligation to provide any services to the
Antenna Area.

      C.   Tenant shall have no right to make any changes, alterations, signs,
decoration or other improvements (which changes, alterations, signs, decoration
or other improvements, together with the Antenna, are hereby collectively
referred to as "Rooftop Installations") to the Antenna Area or to the Antenna
without Landlord's prior written consent.

      D.   Landlord shall provide Tenant with 24-hour access to the Antenna
Area, subject to Landlord's reasonable security procedures and restrictions
based on emergency conditions and to other causes beyond Landlord's reasonable
control. Tenant shall give Landlord reasonable advance written notice of the
need for access to the Antenna Area (except that such notice may be oral in an
emergency), and Landlord must be present during any entry by Tenant onto the
Antenna Area. Each notice for access shall be in the form of a work order
referencing the lease and describing, as applicable, the date access is needed,
the name of the contractor or other personnel requiring access, the name of the
supervisor authorizing the access/work, the areas to which access is required,
the Building common elements to be impacted (risers, electrical rooms, etc.) and
the description of new equipment or other Rooftop Installations to be installed
and evidence of Landlord's approval thereof. In the event of an emergency, such
notice shall follow within five (5) days after access to the Antenna Area.

      E.   At the expiration or prior termination of Tenant's right to use the
Antenna Area, Tenant shall remove all Rooftop Installations (including, without
limitation, the Antenna) from the Antenna Area.

      F.   Tenant shall be responsible for the cost of repairing any damage to
the roof of the Building caused by the installation or removal of any Rooftop
Installations.

      G.   Tenant shall have no right to sublet the Antenna Area, except in
connection with a sublease permitted hereunder or otherwise approved by Landlord
in accordance with the terms hereof.

      H.   No person, firm or entity (including, without limitation, other
tenants, licensees or occupants of the Building or the Park) shall have the
right to benefit from the services provided by the Antenna other than Tenant.
<PAGE>

      I.   In the event that Landlord performs repairs to or replacement of the
roof, Tenant shall, to the extent reasonably required, at Tenant's cost, remove
the Antenna until such time as Landlord has completed such repairs or
replacements. Tenant recognizes that there may be an interference with Tenant's
use of the Antenna in connection with such work. Landlord shall use reasonable
efforts to complete such work as promptly as possible and to perform such work
in a manner which will minimize or, if reasonably possible, eliminate any
interruption in Tenant's use of the Antenna.

      J.   Any services required by Tenant in connection with Tenant's use of
the Antenna Area or the Antenna shall be installed by Tenant, at Tenant's
expense, subject to Landlord's prior approval.

      K.   To the maximum extent permitted by law, all Rooftop Installations in
the Antenna Area shall be at the sole risk of Tenant, and Landlord shall have no
liability to Tenant in the event that any Rooftop Installations are damaged for
any reason, except to the extent caused by the gross negligence or willful
misconduct of Landlord, its agents or contractors.

      L.   Tenant shall take the Antenna Area "as-is", in the condition in which
the Antenna Area is in as of the Commencement Date in respect of the Antenna
Area.

      M.   Tenant shall comply with all applicable laws, ordinances and
regulations in Tenant's use of the Antenna Area and the Antenna.

      N.   Landlord shall have the right, upon sixty (60) days notice to Tenant,
to require Tenant to relocate the Antenna Area to another area ("Relocated
Rooftop Area") on the roof of the Building suitable for the use of the Rooftop
Installations. In such event, Tenant shall, at Landlord's cost and expense, on
or before the sixtieth (60th) day after Landlord gives such notice, relocate all
of its Rooftop Installations from the Antenna Area to the Relocation Rooftop
Area.

      O.   In addition to complying with the applicable construction provisions
of the Lease, Tenant shall not install or operate Rooftop Installations in any
portion of the Antenna Area until (x) Tenant shall have obtained Landlord's
prior written approval, which approval will not be unreasonably withheld or
delayed, of Tenant's plans and specifications for the placement and installation
of the Rooftop Installations in the Antenna Area, and (y) Tenant shall have
obtained and delivered to Landlord copies of all required governmental and
quasi-governmental permits, approvals, licenses and authorizations necessary for
the lawful installation, operation and maintenance of the Rooftop Installations.
The parties hereby acknowledge and agree, by way of illustration and not
limitation, that Landlord shall have the right to withhold its approval of
Tenant's plans and specifications hereunder, and shall not be deemed to be
unreasonable in doing so, if Tenant's intended placement or method of
installation or operation of the Rooftop Installations (i) may subject other
licensees, tenants or occupants of the Building or the Complex, or other
surrounding or neighboring landowners or their occupants, to signal
interference, Tenant hereby acknowledging that a shield may be required in order
to
<PAGE>

prevent such interference, (ii) does not minimize to the fullest extent
practicable the obstruction of the views from the windows of the Building that
are adjacent to the Rooftop Installations, if any, (iii) does not complement (in
Landlord's sole judgment, which shall not, however, require Tenant to incur
unreasonable expense) the design and finish of the Building, (iv) may damage the
structural integrity of the Building or the roof thereof, or (v) may constitute
a violation of any consent, approval, permit or authorization necessary for the
lawful installation of the Rooftop Installations.

      P.   In addition to the indemnification provisions set forth in the Lease
which shall be applicable to the Antenna Area, Tenant shall, to the maximum
extent permitted by law, indemnify, defend and hold Landlord and its agents,
contractors and employees harmless from and against any and all claims, losses,
demands, actions or causes of actions suffered by any person, firm, corporation
or other entity arising from Tenant's use of the Antenna and/or the Antenna
Area.

      Q.   Landlord shall have the right to designate or identify the Rooftop
Installations with or by a lease or license number (or other marking) and to
place such number (or marking) on or near such Rooftop Installations.

      R.   If Tenant installs any additional equipment in the Antenna Area other
than the one (1) Antenna ("Additional Installation"), Tenant shall pay to
Landlord, in the same manner as Base Rent is paid under the Lease, a monthly fee
of $200.00 per Additional Installation.

4.    GENERATOR AREA

      Landlord hereby demises and leases to Tenant, and Tenant hereby hires and
takes from Landlord, an area in an area outside of the Building adjacent to the
loading dock, as designated by Landlord ("Generator Area") for an emergency
generator ("Generator") for a term commencing as of the Term Commencement Date
in respect of the Premises demised to Tenant under the Lease and terminating as
of the Termination Date. Said demise of the Generator Area shall be upon all of
the same terms and conditions of the Lease, except as set forth in this
Paragraph 4. Tenant shall not install or operate the Generator until Tenant has
installed a concrete pad in the Generator Area, which work shall be subject to
Landlord's prior written consent, not to be unreasonably withheld or delayed,
and obtained and submitted to Landlord copies of all required governmental
permits, licenses, and authorizations necessary for the installation and
operation of the Generator. In addition, Tenant shall comply with all reasonable
construction rules and regulations promulgated by Landlord in the installation,
maintenance and operation of the Generator. Tenant shall be permitted to use the
Generator Area solely for the maintenance and operation of the Generator, and
the Generator and Generator Area are solely for the benefit of Tenant. All
electricity generated by the Generator may only be consumed by Tenant in the
Premises.

      A.   Tenant shall have no obligation to pay Yearly Rent, Tax Excess or
      Operating Expense Excess in respect of the Generator Area.
<PAGE>

      B.   Landlord shall have no obligation to provide any services including,
      without limitation, electric current, to the Generator Area.

      C.   Tenant shall have no right to make any changes, alterations,
      additions, decorations or other improvements (collectively
      "Installations") to the Generator Area without Landlord's prior written
      consent, which consent shall not be unreasonably withheld or delayed.

      D.   The Generator and any Installations may be removed by Tenant at any
      time and shall be removed by Tenant at the expiration or earlier
      termination of the term of the Lease, provided that Tenant has paid for
      the Generator and Installations and provided further that Tenant repairs
      any damage to the Building or the Property caused by the installation or
      removal of the Generator and/or Installations. In addition, if so directed
      by Landlord, Tenant shall, at the expiration or earlier termination of the
      term of the Lease, remove the concrete pad and restore the land to the
      condition in which it was in prior to the installation of the concrete
      pad.

      E.   Tenant shall be responsible for the cost of repairing any damage to
      the Building caused by the installation of the Generator and/or any
      Installations.

      F.   Tenant shall have no right to sublet the Generator Area or to assign
      its interest hereunder.

      G.   To the maximum extent permitted by law, the Generator and all
      Installations in the Generator Area shall be at the sole risk of Tenant,
      and Landlord shall have no liability to Tenant in the event that the
      Generator or any Installations are damaged for any reason.

      H.   Tenant shall take the Generator Area "as-is" in the condition in
      which the Generator Area is in as of the Term Commencement Date, without
      any obligation on the part of Landlord to prepare or construct the
      Generator Area for Tenant's use or occupancy. Without limiting the
      foregoing, Landlord makes no warranties or representations to Tenant as to
      the suitability of the Generator Area for the installation and operation
      of the Generator.

      I.   In addition to and without limiting Tenant's obligations under the
      Lease, Tenant shall comply with all applicable environmental and fire
      prevention laws, ordinances and regulations in Tenant's use of the
      Generator Area.

      J.   In addition to and without limiting Tenant's obligations under the
      Lease, Tenant covenants and agrees that the installation and use of the
      Generator and Installations shall not adversely affect the insurance
      coverage for the Building. If for any reason, the installation or use of
      the Generator and/or the Installations
<PAGE>

      shall result in an increase in the amount of the premiums for such
      coverage, then Tenant shall be liable for the full amount of any such
      increase.

      K.   Tenant shall, at Tenant's sole cost and expense, repair and maintain
      the Generator and Installations.

      L.   In addition to and without limiting the insurance provisions of the
      Lease, Tenant shall procure, keep in force and pay for Commercial General
      Liability Insurance in respect of the Generator Area of not less than Two
      Million ($2,000,000.00) Dollars in the event of personal injury to any
      number of persons or damage to property, arising out of any one occurrence
      and such insurance shall name Landlord as an additional insured party.
      Notwithstanding anything to the contrary herein contained, the provisions
      of Articles 15.1 and 15.2 of the Lease, except to the extent inconsistent
      with this Paragraph 4, shall apply to the Generator Area.

      M.   In addition to and without limiting the indemnification provisions
      set forth in the Lease, Tenant shall, to the maximum extent permitted by
      law, indemnify, defend, and hold Landlord harmless from any and all
      claims, losses, demands, actions, or causes of actions suffered by any
      person, firm, corporation, or other entity arising from Tenant's use of
      the Generator Area.

      N.   Notwithstanding anything to the contrary herein or in the Lease
      contained, in the event that at any time during the term of the Lease in
      respect of the Generator Area, Landlord determines, in its bona fide
      business judgment, that the Generator and/or any Installations interfere
      with the operation of the Building or the operations of any of the
      occupants of the Building, then Tenant shall, upon notice from Landlord,
      cease any further operation of the Generator. From and after such notice
      from Landlord, Tenant shall have no further right to operate the Generator
      unless and until Tenant shall have redesigned and modified the Generator
      and/or Installations in a manner approved by Landlord, which approval
      shall not be unreasonably withheld, provided however, that Landlord's
      approval of such redesign and modification shall constitute the mere
      permission of Tenant to operate the Generator, which permission shall in
      no event be construed to abrogate or diminish Landlord's rights or
      Tenant's obligations under this Paragraph 4. Notwithstanding the
      foregoing, Landlord shall not require Tenant to cease further operation of
      the Generator pursuant to this Subparagraph N during any period of time
      when Tenant is using the Generator as an emergency backup source at the
      Premises.