<PAGE>

                                                                   EXHIBIT 10.07

                                     LEASE
                                     -----


    THIS AGREEMENT, made as of the ___ day of _________, 1999, between LONG
WHARF DRIVE, LLC, a Connecticut limited liability company with an office at 4
Hamilton Street, New Haven, Connecticut, 06511 ("Landlord") and dsl.net,
incorporated, a Delaware corporation with an office at 50 Washington Street,
Norwalk, Connecticut 06854 ("Tenant").

                                  WITNESSETH:


1.  LEASED PREMISES:

A.  Premises and Building
    ---------------------

Landlord does hereby lease to Tenant and Tenant does hereby rent from Landlord
those certain premises which are deemed to contain approximately 12,078 rentable
square feet of space located on the fifth (5th) floor (hereinafter called the
"Premises"), as designated on the plan attached hereto as EXHIBIT A and made a
                                                          ---------
part hereof, said Premises being situated in the Building known as 545 Long
Wharf Drive, New Haven, Connecticut 06511 (hereinafter called the "Building").
The legal description of the land on which the Building is situated (the "Land")
is set forth on EXHIBIT A-1 attached hereto and made a part hereof The Land, the
                -----------
Building and any other improvements located on the Land are collectively
referred to herein as the "Property." Landlord hereby reserves and Tenant shall
have no right in and to (a) the use of the exterior faces of all perimeter
walls; (b) the use of the roof; and (c) the use of the land, improvements and
space below the bottom of the lower floor slabs and above the interior surface
of the ceiling of the Premises. Said letting and renting is upon and subject to
the terms, covenants, and conditions set forth herein, and Tenant covenants as a
material part of the consideration for this Lease to keep and perform each and
all of the said terms, covenants, and conditions by it to be kept and performed.
This Lease is made upon the condition of such performance.

EXHIBIT A-2 annexed hereto and made apart hereof sets forth the general layout
-----------
of the Property and shall not be deemed to be a warranty, representation or
agreement on the part of Landlord that the Building or other improvements on the
Land will remain as indicated on said plan.

If the Commencement Date has not occurred within two (2) years of the date of
this Lease, this Lease shall automatically terminate without further action by
either Landlord or Tenant.

B.  Parking
    -------

Throughout the Term, Landlord shall provide 2.67 unreserved parking spaces in
the parking lot located on the Property for every 1,000 rentable square feet of
the Premises.  Landlord may increase, reduce or change (in any manner
whatsoever) the dimensions or locations of the parking facility as Landlord
shall deem proper, including the increasing or decreasing the number of parking
spaces, provided however, that in the event Landlord reduces the number of
parking
<PAGE>

spaces, other than in accordance with Paragraph 18 hereof, Tenant shall continue
to receive the number of spaces provided , pursuant to the ratio set forth in
the immediately preceding sentence. Said parking spaces may not be assigned,
transferred or in any way encumbered except in conjunction with a Landlord
approved be assignment or subletting pursuant to Section 13 hereof. The parking
spaces are for the sole use and occupancy of Tenant, its employees, agents and
business invitees. Landlord shall have the right, from time to time, to change
the area, level and arrangement of the parking areas and to change parking
access routes. Tenant agrees that no such change, nor any temporary
unavailability of any of said parking spaces shall constitute an actual or
constructive eviction, in whole or in part, or entitle Tenant to any abatement
or diminution of "Rent," as defined herein, or relieve Tenant from any of its
obligations under this Lease.


2.  TERM, POSSESSION AND USE:

A.  Term
    ----

This lease is for a term of six (6) years ("Term") commencing on the
"Commencement Date", as hereinafter defined and expiring on the last day of the
seventy-second (72nd) full calendar month following the Commencement Date (the
"Expiration Date").  The Commencement Date notwithstanding, this Lease and all
of the terms and conditions hereof shall be binding upon and shall inure to the
benefit of the parties hereto as of the date Tenant takes occupancy of the
Premises and/or that certain temporary space, consisting of approximately 2,500
rentable square feet, located on the fifth (5th) floor of the Building, as more
particularly shown on EXHIBIT A-3 annexed hereto and made a part hereof (the
                      -----------
"Temporary Space") for Tenant's temporary use for general office purposes.  The
"Commencement Date" of this Lease shall be the later to occur of (A) the date
the Premises is "Substantially Completed", as defined below, and (B) March 1,
1999.  Landlord shall, in accordance with the foregoing, fix the Commencement
Date and shall notify Tenant of the date so fixed.  When the Commencement Date
has been so determined, at Landlord's request, the parties hereto shall, within
fifteen (15) days after such request, execute a written agreement in the form
annexed hereto as EXHIBIT C which will delineate the following: the Commencement
                  ---------
Date and the Expiration Date.  Tenant's failure to take occupancy of the
Premises by the Commencement Date shall constitute an event of default under the
Lease.

B.  The Premises shall be deemed "Substantially Completed" when Landlord has
completed the construction work which is shown on the plans (the "Construction
Plans") which are narratively described by title block in EXHIBIT B annexed
                                                          ---------
hereto and made a part hereof (the "Construction Work"), as determined by
Landlord's project architect or construction manager, despite the fact that
minor or insubstantial details of construction, decoration or mechanical
adjustment remain to be performed provided said minor items can be fully
performed within sixty (60) days without material interference with Tenant's use
of the Premises.

C.  Use of Premises
    ---------------

                                      -2-
<PAGE>

Tenant covenants and agrees to occupy the Temporary Space and the Premises
exclusively for general office purposes, consistent with the first class nature
of the Building.  Tenant shall use the Premises in a careful, safe, and proper
manner and agrees to pay for any damage to the Building or Premises caused by
misuse or abuse by Tenant, its agents or employees, or by any other person
entering upon the Building and/or the Premises under the express or implied
invitation of Tenant.  Such payment shall be made within thirty (30) days of
such damage.  Tenant shall not conduct any activity or perform any act
prohibited by the laws of the United States of America or the State of
Connecticut or the ordinances of the City of New Haven and shall not commit
waste nor suffer waste to be committed, nor permit any nuisance on or in the
Premises.  Tenant understands that all "Common Areas" as defined herein, of the
Building are to be shared in common with all other tenants and that they shall
be subject to the exclusive control and management of the Landlord.

Tenant shall have the right to the nonexclusive use, in common with others, of
those driveways, walks, and other facilities on the Property as may be provided,
from time to time, by Landlord for use of the tenants of the Building
(hereinafter called "Common Areas").  Landlord may at any time and from time to
time, in its sole discretion increase, decrease or change in any manner the
Common Areas.  Landlord may at any time close temporarily the Common Areas to
make repairs or changes or to effect construction, repairs or changes within the
Building.  No such action of Landlord shall be deemed to be an eviction of
Tenant, or breach of this Lease, nor give rise to any claim for damages or for a
reduction of any Base Rent, "Tenants Proportionate Share of Operating and Tax
Expenses," as defined herein, or "Additional Rent," as defined herein (sometimes
collectively referred to herein as "Rent"); provided, however, no action shall
be taken by Landlord which would eliminate or substantially reduce, access to
the Premises.  The Common Areas shall not be decreased, changed or closed in
such a manner or for such a time so as to adversely affect the first class
reputation and nature of the Building.

D.  Option to Extent Term
    ---------------------

So long as (i) Tenant shall not be in default hereunder, (ii) the Lease has not
been assigned or subleased in any manner, and (iii) the Lease shall be in full
force and effect, both at the time of giving notice as required in this Section
2.D and at the time of the commencement of any Extension Period, Tenant shall
have the right, at its election, to extend the Term for two (2) additional five
(5) year period(s) (respectively, the "Extension Period") commencing upon the
expiration of the Terms or the first Extension Period, as the case may be,
provided that Tenant shall give Landlord notice of the exercise of its election
at least nine (9) months prior to the expiration of the Term or the first
Extension Period, as the case may be.  Time is of the essence with respect to
the exercise by Tenant of the option(s) to extend.  Prior to the exercise by
Tenant of the election to extend the Term, the expression "Term" or any
equivalent expression shall mean the Term then in effect; after the exercise by
Tenant of any such election, the expression "Term" or any equivalent expression
shall mean the Term as it may have been then extended.  All terms, covenants,
agreements and conditions in this Lease contained shall apply to the Extension
Period to witch the Term shall be extended as aforesaid, including, without
limitation, the obligation to pay Additional Rent in accordance with Section 3.
below, excepting (i) such

                                      -3-
<PAGE>

provisions of this Lease which by their terms are only applicable to the initial
seventy-two (72) month Term or the then existing Extension Period, including any
further right extension and, (ii) Base Rent for each Extension Period shall be
the fair market rental value for the Premises at the time, as determined by
Landlord in its commercially reasonable discretion.

E.  Occupancy of Temporary Space
    ----------------------------

As of February 1, 1999, Tenant shall be permitted to use and occupy the
Temporary Space.  Tenant acknowledges that it has inspected the Temporary Space
and accepts the same in its existing "AS IS" condition and Landlord shall have
no obligation to improve, equip or decorate the Temporary Space in any manner
whatsoever.  Tenant shall make no improvements to the Temporary Space of any
nature without, in each instance, obtaining Landlord's prior written consent
which Landlord may withhold in its sole discretion.  Tenant may occupy the
Temporary Space until the Commencement Date.  Thereupon, Tenant shall vacate the
Temporary Space and leave the same in broom clean condition and in accordance
with Section 34(D) of this Lease.

Commencing February 1, 1999 and continuing on the first day of each calendar
month through and including the Commencement Date (the "Temporary Space Term"),
in addition to and not in lieu of Tenant's other obligations under this Lease,
Tenant shall pay to Landlord, in the manner provided in Section 3 below, for its
use and occupancy of the Temporary Space, Base Rent in the amount of Two
Thousand Nine Hundred Sixteen and 67/100 Dollars ($2,916.67). Tenant shall also
be responsible during the Temporary Space Term for payment of its Proportionate
Share of Operating and Tax Expenses as defined below, except that Tenant's
proportionate share of such costs for Tenant's use and occupancy of the
Temporary Space, shall be 0.94%. If Tenant fails to vacate the Temporary Space
by the Commencement Date, the same shall constitute an event of default under
this Lease and, in addition to the other rights afforded Landlord hereunder, the
provisions of Section 26 hereof shall apply to such holdover.


3.  RENT

Tenant shall pay to Landlord as Rent, at Landlord's office, or as directed from
time to time by Landlord's notice, during each year of the Term hereof, without
prior notice, demand, recoupment or setoff whatsoever, Base Rent, Tenant's
Proportionate Share of Operating and Tax Expenses and Additional Rent as
provided in this Article 3. As used in this Lease, the following terms shall
have the following respective meanings:

Base Rent: The Base Rent payable during the initial Term shall be One Hundred
Sixty-Nine Thousand Ninety-Two and 00/100 Dollars ($169,092.00) per annum (based
on a per rentable square foot per annum rate of $14.00), which shall be payable,
in advance, in equal monthly installments of Fourteen Thousand Ninety-One and
00/100 Dollars ($14,091.00).

Additional Rent: Any required payments to Landlord from Tenant, including but
not limited to Tenant's proportionate Share of Operating and Tax Expenses.

                                      -4-
<PAGE>

Electricity Charges:  Landlord's payments to the electrical utility provider for
electricity usage charges and electricity demand charges in the Building.

Lease Year:  "Lease Year" shall mean the period from the Commencement Date to
the expiration of the first full twelve (12) calendar month period of the Term
of this Lease and each succeeding twelve (12) month period for the Term of this
Lease and any Extended Term.  If the Commencement Date is not the first day of a
calendar month, the first Lease Year shall be twelve (12) months plus the
remaining portion of the partial month of the month containing the Commencement
Date.  Periods of less than a full Lease Year shall be equitably pro-rated.

Operating Year: Each calendar year in which any part of the Term of the Lease
shall fall.

Operating and Tax Expenses: The aggregate of the Operating Expenses and Taxes.

Operating Expenses: The aggregate costs or expenses reasonably incurred by
Landlord with respect to the operation, cleaning, repair, maintenance and
management of the Property and with respect to the Electricity Charges, as more
particularly enumerated hereinafter in this Section 3. For each Operating Year
during the Term, Operating Expenses shall be adjusted as necessary to reflect
the Operating Expenses which would have been incurred had the leaseable areas of
the Building been at least 95% occupied during the entire Operating Year.

Taxes:  The real estate taxes and other special assessments assessed with
respect to the Property and/or any other tax, if the same replaces the current
method of assessment of real estate taxes in whole or in part or is additionally
imposed on the Property or upon Landlord relating to the Property and is
generally applicable to owners of singular properties.  Notwithstanding the
foregoing, if the Tenant makes or causes improvements in the Premises, whether
installed and/or paid for by Landlord or Tenant and whether or not affixed to
the real property so as to become a part thereof, which improvements are
assessed for real property tax purposes at a valuation higher than the valuation
at which tenant improvements conforming to the Building Standard are assessed,
then the real property taxes and assessments levied against Landlord or the
Building by reason of such excess assessed valuation shall be deemed to be taxes
levied against personal property of Tenant and shall be solely the
responsibility of Tenant.  If the records of the tax assessor are available and
sufficiently detailed to serve as a basis for determining whether said tenant
improvements are assessed at a higher valuation than Building Standard, such
records shall be binding on both Landlord and Tenant; otherwise the actual cost
of the construction shall be the basis for such determination.

Tenant's Proportionate Share: The quotient derived by dividing the sum of the
rentable square feet in the Premises by the total number of rentable square feet
in the Building, which quotient as of execution date of this agreement is 4.52%.

                                      -5-
<PAGE>

Tenant's Proportionate Share of Operating and Tax Expenses: Tenant's
Proportionate Share of the Operating and Tax Expenses.

A.  Payment
    -------

Tenant shall pay the Base Rent to Landlord, or as otherwise directed by Landlord
with appropriate notice, commencing on the Commencement Date, without offset,
abatement, deduction or demand.  Such Base Rent shall be payable in equal
monthly installments, in advance, on the first day of each and every calendar
month during the Term of this Lease, at Landlord's Notice Address, or at such
other place as Landlord shall from time to time designate by notice.  Base Rent
shall be paid without benefit of monthly invoice.  The first sentence of this
Section A. notwithstanding, provided Tenant is not in default under any of the
terms and conditions of this Lease, the Base Rent shall be abated for the period
commencing on the Commencement Date and ending on that day which is ninety (90)
calendar days after the Commencement Date (the "Abatement Period").  During the
Abatement Period, all of the other obligations, liabilities, terms and
conditions contained herein shall apply and remain in full force and effect.

Base Rent for any partial month shall be pro-rated on a daily basis, and if Base
Rent commences on a day other than the first day of a calendar month, the first
payment which Tenant shall make to Landlord shall be payable on the date Base
Rent commences and shall be equal to a proportionate part of the monthly
installment of Base Rent for the partial month in which Base Rent commences.

Commencing on the Commencement Date and continuing thereafter, during the Term,
Tenant shall pay to Landlord (without offset, abatement, deduction or demand)
Tenant's Proportionate Share of all Operating and Tax Expenses, said payments to
be made monthly on the first day of each and every calendar month during the
Term and otherwise in the manner herein provided for the payment of Base Rent,
which amount shall be apportioned for any Operating Year in which the
Commencement Date falls or the Term of this Lease expires or otherwise
terminates.  Landlord shall be reasonably consistent, year to year, in its
accounting of expenses.

Except as provided above, commencing on the Commencement Date, Tenant shall pay
to Landlord (without offset, abatement deduction or demand) Tenant's
Proportionate Share of all Operating and Tax Expenses.  The first sentence of
this subparagraph notwithstanding, provided Tenant is not in default under any
of the terms and conditions of this Lease, Tenant's Proportionate Share of
Operating and Tax Expenses shall be abated for the Abatement Period.  Estimated
payments by Tenant on account of Tenant's Proportionate Share of Operating and
Tax Expenses shall be made monthly on the first day of each and every calendar
month during the Term of this Lease and otherwise in the manner herein provided
for the payment of Base Rent.  The monthly amount so to be paid to Landlord
shall be sufficient to provide Landlord by the end of each Operating Year a sum
equal to Tenant's required payments, as reasonably estimated by Landlord from
time to time during each Operating Year, on account of Tenant's Proportionate
Share of Operating and Tax Expenses for such Operating Year.  Within one hundred
twenty

                                      -6-
<PAGE>

(120) days after the end of each Operating Year, Landlord shall submit to
Tenant a reasonably detailed accounting of Tenant's Proportionate Share of
Operating and Tax Expenses for such Operating Year in accordance with generally
accepted accounting practices.  If estimated payments theretofore made for such
Operating Year by Tenant exceed Tenant's required payment on account thereof for
such Operating Year, according to such shall within thirty (30) days thereafter
pay to Tenant the amount of the overpayment; and, if the required payments on
account thereof for such Operating Year are greater than the estimated payments
(if any) theretofore made on account thereof for such Operating Year, Tenant
shall promptly make payment to Landlord within thirty (30) days after having
received such accounting detail and an invoice from Landlord.  Such invoices
shall be conclusive and binding upon Tenant unless within ninety (90) days after
the receipt of such statement Tenant shall notify Landlord that it disputes the
correctness thereof and specifying the particular respects in which the
statement is claimed to be incorrect.  Tenant shall continue to pay disputed
amounts until such time as the dispute has been settled.  The preceding sentence
notwithstanding, within three (3) years after receipt of Landlord's accounting
of Tenant's Proportionate Share of Operating and Tax Expenses, Tenant shall have
the right, by not less than ten (10) days prior notice to Landlord, to audit
the amount of any item in any of the previous accounting statement, but Tenant
shall continue paying Tenant's Proportionate Share of Operating and Tax
Expenses.  Any such audit shall be conducted by an internal auditor of Tenant,
or a nationally recognized public accounting firm, but in either event, no such
person or entity engaged by Tenant to conduct an audit shall be hired or paid on
any contingency fee basis.  Any audit conducted by Tenant shall be at Tenant's
sole cost and expense and shall be conducted during Landlord's regular business
hours and at Landlord's principal place of business.  Tenant shall deliver a
copy of any such audit to Landlord and if such audit discloses an overpayment of
Operating and Tax Expenses by Tenant, and Landlord verifies same, the Tenant
shall be entitled to a credit in the amount of said overpayment against the next
monthly payment of Base Rent.

B.  Operating Expenses
    ------------------

Operating Expenses shall mean all costs and expenses (whether or not presently
within the contemplation of the parties) paid or incurred, directly or
indirectly, by Landlord in operating, managing, equipping, repairing, replacing,
policing and/or maintaining the Building or Property, or any part thereof, witch
shall include the following costs by way of illustration, but shall not be
limited to: same, wages, hospitalization, medical, surgical, and general welfare
benefits (including group life insurance), and pension payments of agents or
employees of Landlord engaged in the operation or maintenance of the Building
(all of which shall be prorated to the extent any such agent or employee does
not work full time at the Building); payroll charges and/or taxes; workers
compensation insurance; lamps; fluorescent tubes; ballasts; steam; fuel; utility
taxes; . electricity, including the Electricity Charges; water (including sewer
charges and/or rental); casualty, business interruption or rent insurance and
liability insurance; repairs and maintenance, including, but not limited to,
repairs and maintenance to the roof, foundation, exterior and interior walls,
floors and covering of same in common areas and structural elements; building
and cleaning supplies; uniforms and dry cleaning; window cleaning; management
fees not to exceed five percent (5%) of the gross revenues of the Property;
service contracts with

                                      -7-
<PAGE>

independent contractors; electricity audit costs; telephone; telegraph,
stationery, advertising; equipment necessary for the maintenance and operation
of the Building; protection and security services; replacements of plate and
window glass; tenant area and common area cleaning and janitorial services;
plant and landscape services; ground maintenance; elevator maintenance and
repair; ice, snow and trash removal; and all other expenses paid in connection
with the operation of the Building. (Operating Expenses shall not include
depreciation on the Building of which the Premises are a part or equipment
therein, loan payments, or real estate broker's commissions Operating Expenses
shall also include, but not be limited to, the capital cost of repairs and/or
replacements, including, but not limited to repairs and replacements of the
roof, foundation, exterior and interior walls, floors and coverings of same in
the Common Areas, structural elements and elements or systems in the Building
which are considered capital items pursuant to generally accepted accounting
principles, or any capital improvements made to the building by Landlord that
reduce Operating Expenses or that are required under any governmental law or
regulation not previously applicable to the Building or not in effect at the
time it was constructed.) Such capital cost shall be amortized over such
reasonable periods as Landlord shall determine consistent with generally
accepted accounting principles. Landlord agrees that all capital costs included
as Operating Expenses shall be net of any insurance proceeds received. Operating
Expenses shall not include the capital costs associated with any expansion of
the Building or the parking area (unless expanded at Tenant's request) nor shall
they include the cost of advertising costs associated with the marketing or
rental of space in the Building.

C.  Tenant's Electrical Usage.  In addition to the payments required of Tenant
    -------------------------
hereunder, Tenant shall be responsible for all costs of electricity furnished
directly by Landlord or the public utility provider to the Premises or any
portion thereof, including, but not limited to, that portion of the Premises to
be used by Tenant as a computer network operations center (the "NOC Area") shown
as the cross-hatched area on EXHIBIT A-4 annexed hereto, and any enlargement or
                             -----------
relocation thereof, which electricity shall be separately submetered.  The costs
initially incurred by Landlord in the purchase and installation of all
submetering equipment for the NOC Area shall be included in "Tenant's Costs" as
defined in Paragraph 5(C)(a) below.  Following the completion of the
Construction Work, all costs subsequently incurred by either party in connection
with submetering the NOC Area in the event the NOC Area is enlarged or
relocated, or for submetering any other portion of the Premises, shall be the
sole obligation of Tenant.  For those areas of the Premises which are not
separately submetered, the cost to Landlord for furnishing electricity to said
areas shall be deemed Electricity Charges, and the same shall be included in
Operating Expenses.

D.   Late Payment
     ------------

If Rent or other payments due Landlord hereunder are received later than ten
(10) days after the same shall be due or if any payment due to Landlord
hereunder on demand is not received within ten (10) days after demand, a late
fee of five percent (5%) of the amount due or Twenty Five Dollars ($25.00),
whichever is the greater, shall be due and payable by Tenant as Additional Rent.
The parties agree that calculation of the exact costs which Landlord will incur
if Tenant makes late payments would be difficult to determine but would include,
without limitation,

                                      -8-
<PAGE>

processing and accounting charges and late charges which may be imposed upon
Landlord by the terms of any mortgage constituting a lien upon the Building. The
parties agree that the late fee provided herein is a fair and reasonable
estimate of the costs the Landlord will incur. If any payment of Base Rent,
Tenant's Proportionate Share of Operating and Tax Expenses, Additional Rent or
any other sums payable by Tenant to Landlord hereunder shall remain unpaid for
ten (10) days after the same shall be due, then in addition to the late fee as
aforesaid interest shall, at Landlord's option, accrue on the unpaid portion
thereof at the following rate and shall be payable by Tenant on demand: at the
lesser of (i) eighteen percent (18%) per annum or (ii) the maximum rate then
permissible under Connecticut law, until paid. This provision, or payment by
Tenant hereunder, or action taken by Landlord hereunder shall not diminish or
abrogate Tenant's duty to pay Rent when due, or Landlord's rights to declare
default for late payment as provided elsewhere in this Lease.

E.  Covenant to Pay Rent
    --------------------

All Rent payments provided for herein shall be due at the time stipulated and
shall be due and payable in full without abatement, off-set, recoupment or
deduction of any kind.  Tenant's covenant to pay Rent shall at all times exist
as an independent covenant.

4.  LETTER OF CREDIT:

Tenant has deposited, and shall maintain on deposit with Landlord at all times
during the initial Term of this Lease, one or more unconditional, irrevocable
letter(s) of credit (each a "Deposit L/C") in the "Required Amount" (as
hereinafter defined), as security for the full and prompt payment, performance
and observance by Tenant of all of the covenants and obligations to be paid,
performed and/or observed on the part of Tenant under this Lease and for the
payment of any and all damages for which Tenant, shall be final by reason of any
act or omission contrary to any of the provisions of this Lease.  Each Deposit
L/C shall be issued by a bank reasonably acceptable to Landlord and shall be
substantially in the form of the letter of credit attached hereto on Exhibit D
and made a part hereof.  If any Deposit L/C provides that the amount drawable
thereunder shall cease to be available on a date prior to the date which is
thirty (30) days after the expiration of the fourth (4th) Lease Year, or if the
issuing bank shall give written notice to Landlord that it will not extend such
Deposit L/C for an additional twelve (12) months beyond the then current expiry
date, Tenant shall, at least thirty (30) days prior to the date specified in
such Deposit L/C as being the date on which such drawable amount will cease to
be available, or the then current expiry date, as the case may be, either
furnish to Landlord a renewal or extension of such Deposit L/C or a new Deposit
L/C.  Failure to comply with the provisions of the preceding sentence prior to
the commencement of said thirty (30) day period shall be deemed to be a default
under this Lease and Landlord may, at any time during said thirty (30) day
period, draw upon such Deposit L/C and retain as a security deposit hereunder
the amount so drawn.  As used herein, the term "Required Amount" shall mean (a)
$216,377.37, for the period from the Commencement Date to and including the day
immediately preceding the seventh (7th) full calendar month following the
Commencement Date, (b) $144,936.00, for the period from the first day of the
seventh full calendar month of the term to and including the day immediately

                                      -9-
<PAGE>

preceding the first (1st) anniversary of the Commencement Date, (c) $120,780.00,
for the period from the first anniversary of the Commencement Date to and
including the day immediately preceding the second (2nd) anniversary of the
Commencement Date, (d) $96,624.00, for the period from the second anniversary of
the Commencement Date to and including the day immediately preceding the third
(3rd) anniversary of the Commencement Date, and (e) $72,468.00, for the period
from the third anniversary of the Commencement Date to and including the day
immediately preceding the fourth (4th) anniversary of the Commencement Date.

If Tenant defaults beyond any applicable notice and cure period in the full and
prompt payment, performance and observance of any of the covenants and
obligations to be paid, performed and/or observed on the part of Tenant under
this Lease, including the payment of Base Rent or Additional Rent, or any other
sums or damages payable under this Lease, Landlord, at Landlord's election, may
draw upon the Deposit L/C to the extent required for the payment to Landlord of
any such Base Rent or Additional Rent, or any other sums or damages in respect
of which Tenant is so in default or for any sums which Landlord may expend or
may be required to expend by reason of Tenant's default, including any damages
or deficiency in the reletting of the Premises, whether such damages or
deficiency accrue before or after summary proceedings or other re-entry by
Landlord.  If Landlord shall so draw upon the Deposit L/C, Tenant shall, upon
demand, immediately deposit with Landlord, a new Deposit L/C in an amount equal
to the amount so drawn.  If, at any time after the payment by Tenant to Landlord
of any amounts required to be paid by Tenant under this Lease, Landlord is
required to return or repay to Tenant, for any reason in connection with the
bankruptcy or insolvency of Tenant, any Base Rent or Additional Rent, or any
other sums paid by Tenant to Landlord under this Lease, then at Landlord's
election, the Deposit L/C may be drawn upon and the proceeds thereof applied by
Landlord to offset all or any portion of the amounts so returned or repaid.  If
Tenant shall fully and faithfully pay, perform and observe all of the covenants
and obligations to be paid, performed and/or observed on the part of Tenant
under this Lease, the Deposit L/C shall be returned to Tenant within ninety (90)
days after the fourth (4th) anniversary of the Commencement Date.

In the event of any sale of Landlord's interest in the Building, or a leasing of
the Building (whether or not in connection with a sale or leasing of the Land),
Landlord shall have the right to transfer the Deposit L/C to the vendee or
lessee and Landlord shall, thereupon, be released by Tenant from all liability
for the return of the Deposit L/C and, in such event, Tenant agrees to look
solely to the new Landlord for the return of the Deposit L/C.  It is agreed by
Tenant that the provisions of this Article 4 shall apply to every transfer or
assignment made of the Deposit L/C to a new Landlord.

Tenant further covenants that it will not assign or encumber, or attempt to
assign or encumber, its interest in the Deposit L/C and that neither Landlord
nor its successors or assigns shall be bound by any such assignment or
encumbrance, or attempted assignment or attempted encumbrance.

5.  IMPROVEMENTS AND SERVICES:

                                      -10-
<PAGE>

A.  Construction Work
    -----------------

Landlord will Substantially Complete the Construction Work.

B.  Change Orders
    -------------

Tenant may make minor changes to the Construction Plans subject to Landlord's
prior written approval, which approval shall not be unreasonably withheld.

C.  Tenant's Costs and Improvement Allowance.
    ----------------------------------------

     (a)  Tenant's Costs.  Tenant's costs ("Tenant's Costs") for the
          Construction Work shall be the contract price paid by Landlord, as the
          same may have been revised by any change orders, plus the following:
          (i) permit fees; (ii) space planning and other design costs; (iii)
          fees of a third party construction manager; (iv) fees of architects
          and engineers in connection with the design of the Construction Work;
          (v) general contractor profit and overhead; (vi) administrative fees
          of Landlord in connection with overseeing the design and construction
          of the Construction Work; (vii) the cost of installing submeter(s) in
          the Premises for measuring Tenant's electrical consumption; and (viii)
          all other costs and expenses in connection with the design and
          construction of the Construction Work.

     (b)  Improvement Allowance.  Landlord shall provide Tenant an allowance of
          ---------------------
          up to Twelve and 00/100 Dollars ($12.00) per rentable square foot of
          the Premises (the "Improvement Allowance"), to be applied against
          Tenant's Costs.  Within sixty (60) days of Substantial Completion of
          the Construction Work, Landlord shall furnish to Tenant a final
          accounting of Tenant's Costs.

     (c)  If Tenant's Costs exceed the Improvement Allowance, then Tenant shall
          pay Landlord such excess within ten (10) days after receipt of such
          final accounting, as Additional Rent.

     (d)  If Tenant's Costs exceed Ten and 00/100 ($10.00) per rentable square
          foot of the Premises but are less than or equal to $12.00 per rentable
          square foot of the Premises (the "Excess Tenant's Costs"), annual Base
          Rent shall be increased as follows: The Excess Tenant's Costs shall be
          fully amortized on a straight-line basis over the remaining initial
          Term, using an annual interest factor of 10%, so as to arrive at a
          monthly amortization amount (the "Monthly Amortized Allowance
          Amount").  The Monthly Amortized Allowance Amount shall be added to
          the monthly installment of Base Rent and shall be treated as Base Rent
          for all purposes of this Lease.  Upon determination of the Monthly
          Amortized Allowance Amount, the parties shall enter into an amendment
          to this Lease to establish the increased Base Rent.

                                      -11-
<PAGE>

     (e)  If Tenant's Costs are less than the Improvement Allowance, then the
          unused portion of the improvement Allowance shall be retained by
          Landlord.

D.   Subsequent Improvements
     -----------------------

Tenant covenants and agrees that Tenant shall not make or erect any
improvements, alterations, replacements, additions or accessions or any other
tenant improvements (individually and collectively referred to herein as "Tenant
Improvements") in any manner whatsoever to the Building or to the Premises
without the prior written consent of Landlord, which consent shall not be
unreasonably withheld or delayed.  For the purposes of this Lease, "Tenant's
Improvements" shall include and be defined to mean all work required to be done
in preparing the Premises so that it may be operated for business (other than
the Construction Work), as well as all alterations, decorations, installations,
additions or improvements to the Premises occurring thereafter.  Tenant
covenants and agrees that all Tenant's Improvements shall be done at Tenant's
full cost and expense, shall comply with all applicable governmental
regulations, shall be done only by contractors, subcontractors and mechanics
with respect to whom Landlord has consented, which consent shall not be
unreasonably withheld, shall be done in a manner which will assure labor harmony
at the site and shall be done in a manner which will not unreasonably interfere
with the construction work or other tenants of Landlord's Building.  Tenant
agrees to provide Landlord copies of all plans and specifications for such
improvements, alterations, replacements or accessions and with the name of the
general contractor and, if known, names of any subcontractors and mechanics who
are to perform such work at least fifteen (15) days in advance of the
commencement of any such work.  Landlord shall, within three (3) business days.
of receipt of such copies from Tenant, notify Tenant as to whether Landlord
consents to such plans, specifications, contractors, subcontractors, etc., which
consent shall not be unreasonably withheld, or whether such consent is withheld,
in which case Tenant's contemplated construction shall not commence.  All
electrical and/or mechanical contractors must be specifically approved by
Landlord which approval may be withheld in Landlord's sole discretion.
Notwithstanding the aforesaid, Landlord's consent to Tenant's plans,
specifications, contractors, subcontractors, etc. shall not be construed as
Landlord's consent to Tenant causing work to be done in the Premises in a manner
or under conditions which entitle the person doing the work or furnishing the
materials to a mechanic's or materialmen's lien.  As a condition precedent to
Landlord's consent to the making by Tenant of such Tenant's Improvements to the
Premises, Tenant agrees to obtain and deliver to Landlord written and
unconditional waivers of mechanic's liens upon the real property in which the
Premises are located, for all work, labor and services to be performed and
materials to be furnished in connection with such work, signed by all
contractors, subcontractors, materialmen and laborers who contract for or intend
to perform such work.  Notwithstanding the foregoing, if any mechanic's lien or
other lien is filed against the Premises or the Landlord's Building for work
claimed to have been done for, or materials claimed to have been furnished to
Tenant, it shall be discharged by Tenant within thirty (30) days thereafter, at
Tenant's expense, by filing the bond required by law, or by payment or
otherwise.  If any such mechanics' or other liens be filed against the Land, the
Building or the Premises and Tenant fails to discharge same within thirty (30)
days after such filing, then in addition to any other right or remedy of

                                      -12-
<PAGE>

Landlord, Landlord may, but without obligation to do so, discharge the same by
bonding or by paying the amount claimed to be due.  Any amount paid by Landlord
for the satisfaction of any such lien and all reasonable legal and other costs
incurred by Landlord in procuring such discharge shall be payable by Tenant to
Landlord as Additional Rent on demand.  Tenant covenants and agrees to indemnify
Landlord and hold Landlord harmless of and from any and all claims, costs,
suits, damages and liability whatsoever arising out of or as a result of any
such work done by Tenant or Tenant's contractors, subcontractors, agents or
employees, including reasonable attorney's fees for the defense thereof.
Landlord shall not be liable for any failure of any building facilities or
services caused by alterations, installations and/or additions by Tenant, and
Tenant shall promptly correct any such failure.  In the event Tenant shall not
promptly correct same, Landlord may make such correction and charge Tenant for
the cost thereof.  Such sum due Landlord shall be deemed Additional Rent and
shall be paid by Tenant promptly upon being billed therefor.

Prior to commencing any work pursuant to the provisions of this Lease, Tenant
shall additionally furnish to Landlord: (i) copies of all governmental permits
and authorizations which may be required in connection with such work; (ii) a
certificate evidencing that Tenant (or Tenant's agents or contractors) has
procured worker's compensation insurance covering all persons employed in
connection with the work who might assert claims for death or bodily injury
against Landlord, Tenant or Landlord's Building; and (iii) such additional
personal injury and property damage insurance as Landlord may reasonably require
because of the nature of the work to be done by Tenant.

All Improvements upon the Premises and any replacements therefor, including all
paneling, decorations, partitions, railings, affixed to the realty, except
furniture, movable trade fixtures and movable equipment installed at the expense
of Tenant shall become the property of Landlord and shall remain upon, and be
surrendered with the Premises as a part thereof at the termination of this
Lease, without compensation to Tenant; unless, however, Landlord by notice given
to Tenant no later than thirty (30) days prior to the end of the Term shall
elect to have Tenant remove any or all such Tenant Improvements.  Thereupon
Tenant shall accomplish such removal at its sole cost and repair any damage
caused by such removal.

E.  Customary Services
    ------------------

Landlord shall provide the following services, all of which shall be considered
Operating Expenses:

     (a)  Heating and cooling to the Premises to provide reasonably comfortable
          levels of temperature and ventilation consistent with applicable
          building codes and regulations for the occupants of the Premises under
          normal business operation.  Business hours for the Premises shall be
          between the hours of 7:00 a.m. and 7:00 p.m. Monday through Friday and
          8:00 a.m. to 12:00 p.m. on Saturdays but there shall be excluded from
          business days Connecticut and federal holidays that are normally
          observed by general business offices.

                                      -13-
<PAGE>

     (b)  Water service for lavatory purposes and for drinking, lavatory and
          toilet purposes at a central service area on each floor.

     (c), Cleaning and janitorial services including rubbish removal, to the
          Premises in accordance with Cleaning Specifications, annexed hereto as
          EXHIBIT E, provided the same are kept in reasonable order by Tenant.
          ---------

     (d)  Free and unobstructed access to the Premises on business days and
          access at all other times subject to reasonable security restrictions
          from time to time in effect, and subject always to restrictions based
          on emergency conditions.  Landlord shall provide keys or other
          security devices which will permit such access outside of the hours
          and days above specified.

     (e)  Cleaning and janitorial services to the Common Areas, the other public
          areas of the Building and Property and the exterior walls of the
          Buildings (including the exterior glass), and removal of snow and ice
          from the parking areas, sidewalks and walkways included in the
          Property, also as to maintain such areas in a clean and neat condition
          commensurate with similar office buildings in the New Haven,
          Connecticut area.

     (f)  Electricity for Tenant's general office uses (i.e. lighting, office
          equipment and personal computers) and replacement of light fixtures,
          tubes, lamps, ballasts, bulbs, lenses, globes and switches.

     (g)  One lobby directory sign, the size and location of which shall be
          designated by Landlord in its sole and absolute discretion.

Tenant shall pay Landlord a charge of Twenty-Five and 00/100 Dollars ($25.00)
per hour for any utilities and services, including without limitation, air
conditioning, electric current and water, provided by Landlord by reason of any
use of the Premises at any time other than the times described above or any use
beyond that which Landlord agrees to furnish as described above, or special
electrical, cooling and ventilating needs created in certain areas by telephone
equipment, computers and other similar equipment or uses.

F.   Additional Services
     -------------------

Should Tenant require any additional work or service, including but not limited
to service of the nature described above, including service furnished outside
the stipulated hours, Landlord may on terms to be agreed, upon reasonable
advance notice by Tenant, furnish such service at charges as may be agreed on,
but in no event at a charge less than Landlord's actual cost plus overhead for
the additional services provided.  It is understood that Landlord does not
warrant that any of the services referred to above, or any other services which
Landlord may supply, will be free from reasonable interruption.  Tenant
acknowledges that any one or more such services may be

                                      -14-
<PAGE>

suspended by reason of accident or of repairs, alterations or improvements
necessary to be made (in which event Landlord will use its reasonable efforts to
cure or correct any deficiency in same), or by strikes or lockouts or reason of
operation of law, or causes beyond the reasonable control of Landlord. Any such
interruption or discontinuance of service shall never be deemed an eviction or
disturbance of Tenant's use, and possession of the Premises, or any part
thereof, or render Landlord liable to Tenant for damages by abatement of Rent or
otherwise, or relieve Tenant from performance of Tenant's obligations under this
Lease. Notwithstanding the foregoing, in the event the cessation of any service
renders the Premises untenantable, Rent shall abate but only for the period of
time and in the amount for which Rent reimbursement insurance proceeds are
actually received by Landlord.

6.  QUIET ENJOYMENT:

So long as Tenant shall observe and perform the covenants and agreements binding
on it hereunder, Tenant shall at all times during the Term herein granted,
peacefully and quietly have and enjoy possession of the Premises without any
encumbrance or hindrance by, from, or through Landlord.

7.  LEASE SUBJECT TO SUPERIOR RIGHTS:

This Lease, including the covenant of quiet enjoyment, and all of Tenant's
rights and options hereunder, is subject and subordinate to all present
mortgages affecting the Property or the Building, and to any mortgage which may
hereafter be executed affecting the Property or the Building, and to all
renewals, modifications, consolidations, replacements and extensions thereof.
Tenant hereby agrees to execute, if the same is required or requested, any and
all instruments in writing to subordinate Tenant's rights acquired by this Lease
to the lien of any such mortgage.  Tenant agrees that foreclosure of any
mortgage encumbering the Property or the Building shall not be a constructive
eviction of Tenant and Tenant shall not have the right to appear in any such
foreclosure action.  Tenant hereby agrees to execute, acknowledge, and deliver
any such instrument or instruments as Landlord may determine necessary to carry
out the intent of this Article within ten (10) days of notice from Landlord.
Notwithstanding the foregoing, Tenant agrees to attorn to any purchaser at
foreclosure sale, to any grantee or transferee designated in any deed given in
lieu of foreclosure, or any mortgagee in possession and this Lease shall
thereafter continue in full force and effect, or at the request of such
purchaser, grantee or transferee or mortgagee in possession to enter into a new
lease on the same terms and conditions as this Lease.  Landlord shall use
reasonable efforts to provide Tenant with such subordination, non-disturbance
and/or attornment agreements, provided such agreements do not materially alter
any terms hereof or expand Tenant's financial liability hereunder.

Landlord shall have the right to mortgage, transfer, assign or convey the
Building, Property or any of its rights under this Lease, in whole or in part,
and nothing in this Lease shall be construed as a restriction of Landlord's
ability to do so.

8.  ESTOPPEL CERTIFICATE BY TENANT:

                                      -15-
<PAGE>

Tenant shall at any time and from time to time, within ten (10) days after
written notice from Landlord, execute, acknowledge, and deliver to Landlord a
statement in writing certifying that this Lease is unmodified and in full force
and effect (or, if modified, stating the nature of such modification and
certifying that this Lease, as so modified, is in full force and effect) and the
dates to which the rental, the security deposit, if any, and other charges are
paid in advance, if any, and acknowledging that, to the best of Tenant's
knowledge, there are no offsets, defenses or counterclaims with respect to the
payment of Rent and that there are no uncured defaults on the part of Landlord
hereunder and no events or conditions then in existence which, with the passage
of time or notice or both, would constitute a default on the part of Landlord
hereunder or specifying such defaults, events, or conditions if any are claimed.
Tenant shall also execute and acknowledge such certificates and agreements as
may be required by Landlord's mortgagee, provided such certificates or
agreements do not materially alter any of the Terms hereof or expand Tenant's
financial liability hereunder.  Without limiting the generality of the
foregoing, Tenant shall agree that if Landlord's mortgagee succeeds to
Landlord's interest in the Building or assumes possession or control of the
Building, such mortgagee shall not be liable for any act or omission of any
prior Landlord but Tenant shall not be prohibited from seeking any recovery for
such acts from the prior Landlord.  It is expressly understood and agreed that
any such statement may be relied upon by Landlord or any prospective purchaser
or encumbrancer of all or any portion of the Building or the Property.  Tenant's
failure to deliver such statement within such time shall constitute a breach and
default under this Lease, and shall be conclusive upon Tenant that this Lease is
in full force and effect without modification except as maybe represented by
Landlord, and that there are no uncured defaults in the Landlord's performance.

Tenant, upon request of Landlord, will, from time to time, execute and deliver
to Landlord an instrument in form reasonably satisfactory to Landlord stating
whether or not Tenant has exercised any option to extend the Term of this Lease.


9.  RIGHTS RESERVED TO LANDLORD:

In addition to any other rights of Landlord under this Lease and/or at law or in
equity, Landlord reserves the following rights:

     (a)  After thirty (30) days notice to Tenant, to change the name, number,
          or designation of the Building during the Term of this Lease or any
          extensions hereof without liability to Tenant.

     (b)  To install and maintain a sign or signs on the exterior or interior of
          the Building.

     (c)  To designate all sources furnishing sign painting and lettering, ice,
          drinking water, towels, toilet supplies, shoe shining, vending
          machines, mobile vending service, catering, and like services used on
          the Premises or in the Building.

                                      -16-
<PAGE>

     (d)  Constantly to have pass keys to the Premises.  Said keys shall only be
          for use in the event of emergency or for cleaning and maintenance.

     (e)  On reasonable prior notice to Tenant, to exhibit the Premises to
          prospective tenants during the last twelve (12) months of the Term,
          and to exhibit the Premises at any time during the Term to any
          prospective purchaser, mortgagee, or assignee of any mortgage on the
          Property and to others having a legitimate interest.

     (f)  At any time upon reasonable notice and in a manner which does not
          unreasonably interfere with Tenant's business, to enter the Premises
          to examine and inspect the same or make such repairs, additions, or
          alterations as Landlord may deem necessary or proper for the safety,
          improvement, or preservation thereof.  Landlord shall at all times
          have the right at its reasonable election to make such alterations or
          changes in other portions of the Building as it may from time to time
          deem necessary or desirable.  All such work performed within the
          Premises shall, except in the case of emergency, be performed so as
          not to unreasonably interfere with Tenants use of the Premises.
          Landlord shall not be liable to Tenant for any damage or inconvenience
          thereby suffered by Tenant.

10.   TENANT'S ADDITIONAL COVENANTS:

Tenant covenants at all times during the Term and such further times as Tenant
occupies the Premises or any part thereof

     (a)  To perform promptly all of the obligations of the Tenant set forth in
          this Lease; and to pay when due items of Base Rent, Tenant's
          Proportionate Share of Operating and Tax Expenses, Additional Rent and
          all charges, rates and other sums which by the terms of this Lease are
          to be paid by the Tenant.

     (b)  To conduct its business at all times in a high grade and reputable
          manner so as to help establish and maintain a high reputation for the
          Building.

     (c)  To store all trash and refuse within the Premises and to attend to the
          daily disposal thereof in the manner designated by Landlord; to keep
          all drains inside the Premises clean; to receive and deliver goods and
          merchandise only in the manner and areas designated by Landlord.

     (d)  To comply with "Building Rules and Regulations" ("Rules") which are
          attached hereto as EXHIBIT F and incorporated herein by reference.
                             ---------
          Landlord may from time to time hereafter make Rules or reasonable
          modifications to the Rules and establish reasonable additional Rules
          for the safety, comfort and welfare of the occupants of the Building
          as Landlord deems necessary.  Such Rules, modifications or additions
          shall be binding upon Tenant when a copy is delivered

                                      -17-
<PAGE>

          to Tenant or Tenant's agents or employees in the Premises. Landlord
          shall have no duty or obligation to enforce any Rules, or any term,
          covenant or condition of any other lease, against any other tenant or
          occupant of the Building, and Landlord's failure or refusal to enforce
          any Rule or any term, covenant or condition of any other lease against
          any other tenant or occupant of the Building shall not constitute an
          actual or constructive eviction, in whole or in part, or entitle
          Tenant to any abatement or diminution of Rent, or relieve Tenant from
          any of its obligations under this Lease, or impose any liability upon
          Landlord or its agents by reason of inconvenience or annoyance to
          Tenant, or injury to or interruption of Tenant's business, or
          otherwise.

     (e)  To make all repairs, alterations, additions or replacements to the
          Premises required by any law or ordinance or any order or regulation
          of any public authority because of Tenant's use of the Premises; to
          keep the Premises equipped with all safety appliances so required
          because of such use; to procure any licenses and permits required for
          any such use; and to comply with the orders and regulations of all
          governmental authorities, except that Tenant may defer compliance so
          long as the validity of any such law, ordinance, order or regulation
          shall be contested by Tenant in good faith and by appropriate legal
          proceedings, if Tenant first gives Landlord appropriate assurance
          against any loss, cost or expense on account thereof and if such
          deferral shall not adversely affect the operation of any other areas
          within the Building.

     (f)  Not to place signs of any nature or kind whatsoever in or upon the
          windows of the Premises.  Tenant signage, at Tenant's sole expense,
          will be installed by means of a Building Standard nameplate located at
          the entrance to Tenant's Premises.  Any other signs shall be subject
          to Landlord's approval which may be unreasonably withheld.  Tenant
          shall not use any picture or drawing of the Building in any
          advertisement or promotional material without Landlord's prior written
          consent.  Landlord reserves the right to promulgate standards for all
          window coverings for the Premises and the Building.

     (g)  Not to make any use of the Premises other than the permitted use set
          forth in Section 2.B.

     (h)  Not to injure, overload, deface or otherwise harm the Premises; nor
          commit any nuisance; nor permit the emission of any objectionable
          noise or odor; nor burn any trash or refuse within the Building; nor
          make any use of the Premises which is improper, offensive or contrary
          to any law or ordinance; nor use any advertising medium that may
          constitute a nuisance, such as loudspeakers, sound amplifiers,
          phonographs or radio or television broadcasts in a manner to be heard
          outside the Premises; nor do any act tending to injure the reputation
          of the Building; nor park trucks or delivery vehicles outside the
          Premises so as to interfere unreasonably with the use, of any
          driveways, walks, or parking areas.

                                      -18-
<PAGE>

     (i)  Not permit or suffer to be done any act, matter, thing or failure to
          act in respect of the Premises or use or occupy the Premises or
          conduct or operate Tenant's business in any manner objectionable to
          any insurance company or companies whereby the fire insurance or any
          other insurance then in effect in respect of the Premises or the
          Building or any part thereof shall become void or suspended or whereby
          any premiums in respect of insurance maintained by Landlord shall be
          higher than those which would normally have been in effect for the
          occupancy contemplated within the Building.  In case of a breach of
          this covenant, in addition to all other rights and remedies of
          Landlord hereunder, Tenant shall (a) indemnify Landlord and the
          lessor(s) of any ground or underlying lease(s) and hold Landlord and
          such lessor(s) of any ground or underlying lease(s) harmless from and
          against any loss which would have been covered by insurance which
          shall have become void or suspended because of such breach by Tenant
          and (b) pay to Landlord, as Additional Rent, any and all increases or
          premiums on any insurance, including, without limitation, fire
          insurance and rent insurance, resulting from any such breach.

11.   WAIVER OF PROPERTY AND LIABILITY CLAIMS:

A.  Damage from Water and Similar Sources
    -------------------------------------

Landlord shall not be liable for any damage to any property, or person, at any
time in the Premises, or the Building of which they are a part, from steam,
gases, electricity, or from water, rain, or snow, whether they may leak into,
issue, or flow from any part of said Building, or from the pipes or heating or
air conditioning apparatus of the same, or from any other place.  Tenant shall
give Landlord prompt notice of any accident to or defect in the pipes, heating,
or air conditioning apparatus or electric wires or system.

B.  Damage from Other Causes
    ------------------------

Tenant waives all claims it may have against Landlord, and against Landlord's
agents and employees for injury or damage to person or property sustained by
Tenant or by any occupant of the Premises, or by any other person, resulting
from any part of the Building or any equipment or appurtenances becoming out of
air, or resulting from any accident in or about the Building or resulting
directly or indirectly from any act or neglect of any tenant or occupant of any
part of the Building or of any other person.  If any damage results from any act
of neglect or negligence of Tenant, Landlord may, at Landlord's option repair
such damage and Tenant shall thereupon pay to Landlord upon demand the total
cost of such repair as Additional Rent.  All personal property belonging to
Tenant or any occupant of the Premises that is in or on any part of the Building
shall be there at the risk of Tenant or of such other person only, and Landlord,
its agents and employees shall not be liable for any damage thereto or for the
theft or misappropriation thereof.

C.  Loss of Business, Etc.
    ----------------------

                                      -19-
<PAGE>

Landlord shall not in any event be liable for loss of business of Tenant nor
salaries paid to Tenant's employees, agents, or contractors, nor for any latent
defect in the Premises or in the Building.  Tenant shall give prompt written
notice to Landlord in case of theft, fire, or accidents in the Premises or in
the Building or of defects therein or in the fixtures or equipment.

D.   Indemnification
     ---------------

Tenant covenants and agrees that Tenant will have sole liability for any claims,
demands, penalties, or liabilities that may arise out of or be connected with
Tenant's occupation, use or enjoyment of the Premises, or the Building and will
release, discharge, indemnify Landlord, and hold Landlord and Landlord's
mortgagee harmless from and against all claims, demands, penalties and
liabilities for any damage or injury to persons, firms, corporations or property
suffered, sustained, or incurred as a result of or in connection with or arising
out of any act or omission of Tenant or its agents, employees, contractors,
licensees and business invitees, in connection with the occupation, use, or
enjoyment of the Premises or the Building by Tenant, including the cost of
defending against such claims or demands.  Tenant shall indemnify and save
harmless Landlord and Landlord's mortgagee from and against any and all
liability and damages, and from and against any and all suits, claims, and
demands of every kind and nature, including reasonable counsel fees, by or on
behalf of any person, firm, association or corporation arising out of or based
upon any accident, injury or damage, however occurring, which shall or may
happen during the Term hereof, on or about the Premises, and from and against
any matter or thing growing out of the condition, maintenance, repair,
alteration, use, occupation or operation of the Premises.  In case of any action
or proceeding on any such claim or demand being brought against Landlord or
Landlord's mortgagee, Tenant, upon notice from Landlord, covenants to resist and
defend such action or proceeding.  Landlord may also resist and defend such
action in the event Tenant fails or refuses to do so, and in such event, Tenant
shall reimburse Landlord on demand for all reasonable costs which Landlord may
incur in so doing, as Additional Rent.  Subject to the provisions of Sections
11.A., 11.B., 11.C. and 12.F. hereof, Landlord shall indemnify and hold Tenant
harmless for any and all damage or injury to person or property arising out of
the gross negligence of Landlord, its agents, servants and employees.


12. INSURANCE BY TENANT:

During the Term of this Lease, Tenant, at its sole cost and expense, shall carry
and maintain the following types of insurance, in insurance companies which are
authorized to do business in the State of Connecticut, which have a Best's
Rating of A-X or better and are satisfactory to Landlord in its sole discretion.

A.  Property Insurance
    ------------------

                                      -20-
<PAGE>

All-risk property insurance, on a Special Causes of Loss, Replacement Cost
basis, on all of Tenant's, personal property located within the Premises and on
all Tenant Improvements which may have been made by Tenant or by Landlord on
behalf of the Tenant to the Premises.

B.  Liability Insurance
    -------------------

Comprehensive general liability insurance and personal injury liability
insurance, insuring Tenant and Landlord, against liability for injury to persons
(including death) or damage to property occurring in or about the Premises or
arising out of the ownership, maintenance, use, or occupancy thereof, insuring
against any claim up to $2,000,000.00, in the case of death or bodily injury to
one person and up to $2,000,000.00 in the case of any one accident involving
death or bodily injury to more than one person, and shall insure against any
claim for property damage up to $1,000,000.00 with a contractual obligation
endorsement.

At the reasonable request of Landlord, Tenant shall adjust annually the amount
of the coverage established in this Section 12.B to such amount as, in
Landlord's reasonable opinion, adequately protects Landlord's interest.

C.  Worker's Compensation
    ---------------------

Worker's compensation insurance insuring Tenant from all claims for personal
injury, disease, and/or death under the worker's compensation law of the State
of Connecticut, plus at least $500,000.00 of employers' liability coverage.

D.  Other Insurance
    ---------------

Such other insurance as Landlord may reasonably require.

E.  Tenant To Furnish Copies
    ------------------------

Tenant shall furnish Landlord certificates of insurance evidencing said policies
within ten (10) days after the execution of this Lease and thereafter at least
fifteen (15) days prior to each policy renewal date.  Such policies shall name
Landlord and any mortgagee or property manager of Landlord as additional
insureds and shall provide that coverage may not be canceled or reduced without
at least thirty (30) days' written notice first given to Landlord.  Tenant shall
have the privilege of procuring and obtaining all such insurance through its own
sources; provided, however, that if Tenant fails to produce and maintain said
insurance, Landlord may, but shall not be obligated to, purchase the same at
Tenant's cost, and the cost thereof shall be Additional Rent which shall be due
and payable to Landlord on the date of the next monthly rental installment.
Landlord, however, may elect not to purchase such insurance for Tenant's behalf
and, in lieu thereof, declare Tenant's default hereunder.

F.  Waiver of Subrogation
    ---------------------

                                      -21-
<PAGE>

Notwithstanding anything in this Lease to the contrary, Landlord and Tenant each
hereby waives any and all rights of recovery, claim, action, or cause of action
against the other, its agents, employees, licensees, or invitees for any loss or
damage to or at the Premises or the Property or any personal property of such
party therein or thereon by reason of fire, the elements, or any other cause
which would be insured against under the terms of the insurance policies
referred to hereinabove, regardless of cause or origin, including omission of
the other party hereto, its agents, employees, licensees, or invitees.  Landlord
and Tenant covenant that no insurer shall hold any right of subrogation against
either of such parties and Landlord and Tenant shall obtain waivers of such
subrogation rights from its insurers.  The parties hereto agree that any and all
such insurance policies required to be carried by either shall be endorsed with
a subrogation clause, substantially as follows: "This insurance shall not be
invalidated should the insured waive, in writing prior to a loss, any and all
right of recovery against any party for loss occurring to the property described
therein," and shall provide that such party's insurer waives any right of
recovery against the other party in connection with any such loss or damage.


13.   ASSIGNMENT AND SUBLETTING:

A.  Consent.
    -------

Tenant will not sublet the Premises or any part thereof or transfer possession
or occupancy thereof to any person, firm or corporation, or transfer or assign
this Lease, except pursuant to the provisions of this Article 13.  No subletting
or assignment hereof shall be effected by operation of law or in any other
manner unless with prior written consent of Landlord.  Tenant shall not assign
this Lease or sublet the Premises without Landlord's prior consent which shall
not be unreasonably withheld.  The parties explicitly agree that Landlord shall
be deemed to be acting in good faith in withholding its consent if, among other
reasons, (i) evidence of satisfactory financial capacity of such sublessee or
assignee is not submitted to Landlord or if Landlord determines such financial
capacity of any proposed assignee or sublessee is insufficient to cover Tenant's
obligations under this Lease, (ii) Landlord believes such sublessee's or
assignee's business would be disruptive or objectionable to other Tenants of the
Building, (iii) the nature of such sublessee's or assignee's business would
cause a material increase in Operating Expenses or require a use of the Premises
from that set forth in Article 2.C. or (iv) Tenant's mortgagee(s) does (do) not
grant its (their) consent.

B.  Excess Rent
    -----------

From and after the effective date of an assignment or subletting, Tenant shall
pay to Landlord monthly as Additional Rent fifty percent (50%) of any "Net
Rent," as defined herein which is in excess of (i) the pro-rata share of Rent
then being paid by Tenant for the portion of the Premises being sublet or
assigned, and (ii) in the case of a subletting, all reasonable subleasing
expenses, including, but not limited to attorney's fees, brokerage commissions,
improvements to the Premises and free rent.  For the purposes of this paragraph
"Net Rent" shall mean the Rent accruing to Tenant as the result of such sublease
or assignment.

                                      -22-
<PAGE>

If Tenant or any subtenant or other person claiming through or under Tenant,
shall assign or have assigned its interest as Tenant under this Lease or its
interest as subtenant under any sublease, as the case may be, Tenant shall pay
to Landlord a sum equal to fifty percent (50%) of any consideration paid to
Tenant or any subtenant or other person claiming through or under Tenant for
such assignment.  All sums payable hereunder by Tenant shall be paid to Landlord
as Additional Rent immediately upon receipt thereof by Tenant or by any
subtenant or other person claiming through or under Tenant.

C.  Tenant Not Released
    -------------------

In the event of any subletting of all or any portion of the Premises or
assignment of this Lease by Tenant, Tenant shall remain jointly and severally
liable to Landlord for payment of all Rent stipulated herein and for payment and
performance of all other covenants and conditions contained herein.  Rent due
from Tenant shall not be diminished or abated during any remodeling or
redecoration period.  Landlord may collect Rent from any sublessee or assignee
and apply the net amounts collected to the Base Rent, Tenant's Proportionate
Share of Operating and Tax Expenses, and Additional Rent but no such collection
shall be deemed to be a waiver of the provisions of this Section.  Further,
notwithstanding anything contained herein to the contrary, any and all
unexercised options to extend or renew the Term of this Lease or to expand the
Premises and any and all rights of first offer and similar rights are intended
by both Landlord and Tenant to be personal to dsl.net, incorporated and are not
intended to, and shall not benefit any assignee or sublessee hereunder.  Upon
any assignment or subletting of the Premises or any portion thereof any such
options or rights shall automatically and without any further action by Landlord
terminate and be of no further force and effect.

D.  Transfer to Affiliate
    ---------------------

Notwithstanding anything to the contrary contained in this provision of this
Article 13, Tenant shall have the right to assign this Lease, or sublet all or a
portion of the Premises, without Landlord's consent, to Tenant's parent or to
any entity of which Tenant has a majority ownership and voting control interest,
provided that Tenant shall remain liable under this Lease, notwithstanding such
assignment or sublease, and further provided that any Tenant Improvements in
connection with such subletting are performed in accordance with the terms and
conditions of this Lease and the use of the Premises is consistent with the use
set forth in Article 2.C. hereof.


14.  CONDITION OF PREMISES:

Tenant's taking possession of the Premises shall be conclusive evidence that the
Premises were in good order and satisfactory condition, when Tenant took
possession.  No promise to alter, remodel, repair, or improve the Premises or
the Building has been made by Landlord to Tenant, other than as may be contained
herein.  At the termination of this Lease, Tenant shall return the

                                      -23-
<PAGE>

Premises with all of Tenant's personal property removed therefrom, broom clean
and in as good condition as when Tenant took possession, ordinary wear and tear
excepted, failing which Landlord may restore the premises to such condition and
Tenant shall pay the cost thereof immediately on demand.


15.  OBLIGATION TO REPAIR:

A.  Tenant's Obligation
    -------------------

Tenant agrees and covenants to keep the Premises in as good order, condition,
and repair as when the same were entered upon, ordinary wear and tear excepted.
All damage or injury to the Building or to the Premises, fixtures,
appurtenances, and/or equipment caused by Tenant, its agents, servants,
employees or invitees, shall be repaired, restored, or replaced promptly by
Tenant at its sole cost and expense.  All repairs, restorations, and
replacements shall be in quality and class equal to the original work or
installations and shall be done to Landlord's satisfaction.  If Tenant fails to
keep the Premises in such good order, condition, and repair as required
hereunder, Landlord may restore the Premises to such good order and condition
and make such repairs without liability to Tenant for loss or damage that may
accrue to Tenant's property or business by reason thereof, and upon completion
thereof Tenant shall pay to Landlord upon demand the cost of restoring the
Premises to such good order and condition, as Additional Rent.

B.  Landlord's Obligation
    ---------------------

Landlord shall maintain the structural portions of the Building, including the
roof, the basic plumbing, air conditioning, heating, and electrical systems
installed by Landlord, unless the condition requiring such maintenance is caused
in part or in whole by the act, neglect, fault, or omission of any duty by
Tenant, its agents, servants, employees, or invitees, in which case Tenant shall
pay Landlord the reasonable cost of such maintenance or repairs.  There shall be
no abatement of Rent and no liability of Landlord by reason of any injury or
interference with Tenant's business arising from the making of any repairs,
alterations, or improvements in or to any portion of the Building or the
Premises or in or to fixtures, appurtenances, and equipment therein.  Tenant
waives the right to make repairs at Landlord's expense under any law, statute,
or ordinance now or hereafter in effect.


16.  LIABILITY:

Landlord assumes no liability or responsibility whatever with respect to the
conduct and operation of the business to be conducted in the Premises by Tenant
nor for any loss or damage of whatsoever kind or by whomsoever caused, to
personal property, documents, records, monies, or goods of Tenant or to anyone
in or about the Building.  Tenant agrees to hold Landlord harmless against all
such claims.

                                      -24-
<PAGE>

17.  DAMAGE TO LEASED PREMISES:

A.   Untenantable - Permanent
     ------------------------

If the Premises, the Building, or any portion thereof shall be damaged by fire
or other cause so as to render the Premises wholly untenantable, and if such
damage shall be so great that a licensed architect as selected by Landlord shall
certify within thirty (30) days after date of such occurrence in writing to
Landlord and Tenant that the Premises, with the exercise of reasonable
diligence, cannot be made fit for occupancy within one hundred and eighty (180)
days from the happening thereof, then this Lease shall cease and terminate from
the date of the occurrence of such damage, and Tenant thereupon shall surrender
to Landlord said Premises and all interest therein as granted hereunder, and
Landlord may reenter and take possession of the Premises and remove Tenant
therefrom.  There shall be no liability on the part of Landlord for such
termination.  In the event of such termination, Tenant shall pay Rent duly
apportioned up to the time of the event causing such damage and all Rent
accruing subsequent to such event shall be abated, Landlord being entitled to
receive the proceeds of any insurance maintained by Landlord covering the
Premises.

B.   Untenantable - Temporary
     ------------------------

     (1)  If the Premises are partially damaged by fire or other causes during
          the Term hereof, the Premises, exclusive of Tenant's Improvements,
          shall be repaired by Landlord with reasonable dispatch, and no
          abatement shall be made to Tenant from the Rent corresponding with the
          time during which the Premises cannot be used by Tenant after damage
          occurring as aforesaid.  Landlord shall be entitled to receive the
          proceeds of all insurance maintained by Landlord covering the
          Premises.  For the purposes of this subdivision, "partially damaged"
          shall mean damage which renders forty percent (40%) or less of the
          Premises untenantable.  Notwithstanding the foregoing, in the event
          the Premises are rendered partially untenantable, Rent shall abate
          during the period of untenantability but only for the period of time
          and in the amount for which Rent reimbursement insurance proceeds are
          actually received by Landlord.

     (2)  If the Premises are damaged by fire or other causes and more than
          forty percent (40%) thereof is rendered untenantable, or the means of
          ingress or egress are rendered unusable, Tenant shall notify Landlord
          of such damage within two (2) days after such damage and Landlord
          shall have the option whether such damage shall be repaired or
          rebuilt.  In the event that Landlord shall decide not to repair or
          rebuild, this Lease shall then and thereupon cease and come to an end,
          Landlord shall be entitled to the proceeds of all insurance maintained
          by Landlord covering the Premises and to the proceeds of the Tenant's
          insurance covering the Tenant Improvements to the extent of the
          Landlord's undepreciated value of said Tenant Improvements.  Tenant
          shall be liable for Rent only up to the time of such damage, and
          thereafter there shall be no further liability on the part of the
          parties

                                      -25-
<PAGE>

          hereto by reason of such termination. Tenant shall promptly surrender
          possession of the Premises.

          If Landlord shall decide that the Premises shall be repaired and
          rebuilt following a fire or other cause, Landlord shall give Tenant
          notice thereof within thirty (30) days after receiving notice of such
          damage, and the Premises, exclusive of Tenant's Improvements, shall be
          repaired by Landlord with due diligence taking into account the nature
          of such damage.  Landlord shall use commercially reasonable efforts to
          complete such repair within one hundred and eighty (180) days from the
          date Landlord gave notice to Tenant of such intent to repair,
          excepting delays outside the reasonable control of Landlord, or Tenant
          may cancel this Lease and be under no further obligation to Landlord.
          Tenant shall subrogate, to the extent of the value of the loss
          resulting from such damage, to Landlord's right of recovery from any
          insurance carrier with respect to such loss.  If loss to the Premises
          or any portion thereof which is to be repaired or rebuilt by Landlord
          hereunder is covered by Tenant's insurance policy or policies,
          Landlord shall receive, by assignment or otherwise, all proceeds of
          such insurance other than proceeds for loss or damage to Tenant's
          personal property or trade fixtures.  Tenant shall receive an
          abatement in the Rent payments otherwise due, which abatement shall
          correspond with the period during which and the extent to which the
          Premises cannot be used by Tenant for the ones and purposes
          contemplated by this Lease.  Tenant recognizes that there may be from
          time to time a mortgage or mortgages covering the Property and that
          the foregoing options with respect to repairing and rebuilding are all
          subject to any mortgagee on any current or future mortgage agreeing to
          allow the Premises to be repaired and/or rebuilt under the terms of
          any such mortgage.

     (3)  The Rent hereunder shall in no case be withheld or diminished on
          account of any defect in the Premises or in the Building, any change
          in the condition thereof, any damage occurring thereto, or the
          existence with respect thereto of any violations of the laws or
          regulations of any governmental authority except as otherwise
          specifically provided herein.

C.   Negligence of Tenant
     --------------------

If the fire or other casualty causing damage to the Premises or other parts of
the Building shall have been caused by the negligence or misconduct of Tenant,
its agents, servants, or employees, or of any other person entering the Premises
under express or implied invitation of Tenant, such damage shall be repaired by
Landlord at the expense of Tenant and, in such event, there shall be no
abatement of Rent.  Tenant's liability shall only be to the extent of any
uninsured losses.

D.   Thirty Percent (30%) Damage
     ---------------------------

                                      -26-
<PAGE>

In the event the Building is damaged to the extent of thirty percent (30%) or
more of the replacement cost thereof Landlord may elect to terminate this Lease,
whether the Premises were damaged or not, by giving Tenant notice at any time
within thirty (30) days after such damage occurred that this Lease will
terminate as of the date specified in the notice, but the termination date shall
be no less than thirty (30) and no more than (60) days after the giving of such
notice.  In the event of the giving of such notice, this Lease shall expire and
all interest of Tenant in the Premises shall terminate on the date specified in
such notice and Rent shall be paid to the date of termination.  Thereafter, both
Landlord and Tenant shall be free and discharged of all further obligations
hereunder.

E.  Other Terminations
    ------------------

If the Building shall be damaged by fire or other casualty and any of the
following applies: (a) any mortgagee under a mortgage now or hereafter
encumbering the Property requires that the insurance proceeds payable as a
result of said fire or other casualty be used to reduce or retire the mortgage
debt, (b) the Building is damaged as a result of a risk that is not covered by
Landlord's insurance or the amount of insurance recovered by Landlord is
insufficient to cover the cost of repairing the Building, or (c) the Premises
are materially damaged during the last twelve (12) months of the Term, then, in
any such event, Landlord may, at its option, terminate this Lease by notifying
Tenant in writing of such termination within thirty (30) days after the date of
such damage or casualty, in which event the Rent hereunder shall be abated as of
the date of such notice, and Tenant shall vacate the Premises in accordance with
the requirements of this Lease, including without limitation, Section 32.D.


18.  CONDEMNATION:

Tenant agrees that if the Building, or the Property, or any part thereof, shall
be taken or condemned for public or quasi-public use or purpose by any competent
authority during the Term of this Lease, (or transferred under threat of such
action,) then and in such event all sums that may be awarded for compensation
for such taking shall be the sole property of Landlord.  Tenant shall have no
claim against Landlord and shall not have any claim or rights to any portion of
the amount that may be awarded as damages or paid as a result of any such
condemnation; and all rights of Tenant to damages therefor, if any, are hereby
assigned by Tenant to Landlord.  Upon such condemnation or taking of a material
portion of the parking lot located on the property and/or the Building, the Term
of this Lease, at Landlord's sole option, shall cease and terminate from date of
such taking or condemnation, and Tenant shall have no claim against Landlord for
the value of any unexpired term of this Lease.


19.  NOTICES:

All notices, which may or are required to be given by either party to the other
shall be in writing and mailed by express mail carrier or by United States
Postal Service Certified or Registered

                                      -27-
<PAGE>

mail and shall be deemed effective upon receipt or the failure to accept
receipt. Notice shall be sent to the following addresses (or such other
addresses as the parties shall so advise by notice):

    If to Landlord:

         Long Wharf Drive, LLC
         4 Hamilton Street
         New Haven, CT 06511
         Attention:
                   --------------------------

    With a copy to:

         Joseph K. Fortier, Esq.
         Reid and Riege, P.C.
         One State Street
         Hartford, CT 06103

    If to Tenant:

         dsl.net, incorporated
         50 Washington Street
         Norwalk, CT 06854


20.  DEFAULT AND REMEDIEES:

A.     Default
       -------

The occurrence of any one or more of the following events shall constitute a
default and breach of this Lease by Tenant:

     (1)  The vacating or abandonment of the Premises by Tenant.

     (2)  The failure by Tenant to make any payment of Rent, Tenant's
          Proportionate Share of Operating and Tax Expenses, or Additional Rent
          or other monetary payment required to be made by Tenant hereunder, as
          and when due, where such failure shall continue for a period of ten
          (10) days after such payment becomes due.

     (3)  The failure by Tenant to observe or perform any of the covenants,
          conditions, or provisions of this Lease to be observed or performed by
          Tenant, other than to make payments as required by this Lease, where
          such failure shall continue for a period of thirty (30) days after
          written notice thereof by Landlord to Tenant; provided, however, that
          if the nature of Tenant's default is such that more than thirty (30)
          days are reasonably required for its cure, then Tenant shall not be in

                                      -28-
<PAGE>

          default if Tenant commences such cure within said thirty (30) day
          period and thereafter diligently prosecutes such cure to completion.

     (4)  The making by Tenant of any general assignment or general arrangement
          for the benefit of creditors; or the filing by or against Tenant of a
          petition to have Tenant adjudged a bankrupt, or a petition of
          reorganization or arrangement under any law relating to bankruptcy
          unless, in the case of a petition filed against Tenant, the same is
          dismissed within sixty (60) days; or the appointment of a trustee or a
          receiver to take possession of substantially all of Tenant's assets
          located at the Premises or of Tenant's interest in this Lease where
          possession is not restored to Tenant within thirty (30) days; or the
          attachment, execution, or other judicial seizure of substantially all
          of Tenant's assets located at the Premises or of Tenant's interest in
          this Lease, where such seizure is not discharged within thirty (30)
          days after the levy thereof.

B.   Remedies
     --------

In the event of any default or breach of Tenant, Landlord may at any time
thereafter, with or without notice or demand and without limiting Landlord in
the exercise of any right which Landlord may have by reason of such default or
breach terminate this Lease pursuant to this express stipulation in which event
this Lease shall expire and terminate and Landlord shall be entitled to recover
possession of the Premises in the manner prescribed by the statute relating to
summary process; and Landlord shall have the right to proceed as follows:

(1) Re-enter and take possession of the Premises or any part thereof and
repossess the same as of Landlord's former estate and expel Tenant and those
claiming through or under Tenant, and remove the effects of both or either with
force, if necessary, without being deemed guilty in trespass or of a forcible
entry or detainer and without prejudice to any remedies for arrears of Rent or
preceding breach of covenants. In such event Landlord shall be entitled to
recover from Tenant all damages incurred by Landlord by reason of Tenant's
default, including but not limited to the cost of recovering possession of the
Premises, expenses of reletting, including necessary renovation and alteration
of the Premises, reasonable attorneys fees and any real estate commission
actually paid. Such damages shall bear interest from the date due at the lesser
of (i) eighteen percent (18%) per annum or (ii) the maximum rate then
permissible under Connecticut law, until paid.

(2)  Should Landlord elect to reenter as above provided, or should Landlord take
possession pursuant to legal proceedings or pursuant to any notice provided by
law or otherwise, Landlord may from time to time, without terminating Tenant's
obligations to pay Rent hereunder, relet the Premises or any part thereof for
such terms, at such rentals, and upon such other terms and conditions as
Landlord in its sole discretion may deem advisable. Landlord shall use
reasonable efforts, but shall not be obligated, to relet the Premises, and
nothing herein contained shall under

                                      -29-
<PAGE>

any circumstances be construed so as to require Landlord to lease the Premises
below the then-current market rental rates being obtained for similar office
buildings in the relevant market area or to lease the same to any tenant not
creditworthy or otherwise unacceptable, to Landlord and shall in no way be
responsible or liable for any failure to relet the Premises, or any part
thereof, or for any failure to collect any rent due upon such reletting. In the
event Landlord shall elect to so relet, then any rent received by Landlord from
such reletting shall be applied first, to the payment of any indebtedness other
than Rent due hereunder from Tenant to Landlord; second, to payment of any
reasonable cost of such reletting, including, without limitation, all
repossession costs, legal expenses, attorneys' fees, concessions, moving and/or
storage costs, alteration, remodeling and repair costs, leasing commissions, and
other expenses of preparation for such reletting (collectively, "Reletting
Costs"); third, to the unamortized portion of the Improvement Allowance
amortized on a straight-line basis over the initial term of this Lease, using an
annual interest rate equal to the prime rate announced as such in the Wall
Street Journal, plus two percent (2%), and fourth, to the payment of Rent due
and unpaid hereunder. Tenant shall satisfy and pay any deficiency between the
rents so collected from the total of the amounts for the items listed above as
"first," "second," "third," and "fourth" above. In no event shall Tenant be
entitled to any excess of any rent obtained by reletting over and above the
items listed above as "first," "second," "third," and "fourth" above.

(3)  Tenant, until the end of the Term or what would have been such Term in the
absence of any such event, shall be liable to Landlord as damages for Tenant's
default, for the equivalent of the amount of the Rent, Tenant's Proportionate
Share of Operating and Tax Expenses, the Additional Rent and other charges which
would be payable under this Lease by Tenant if this Lease were still in effect,
plus all Reletting Costs, less the net proceeds of any reletting. Tenant shall
pay such current damages (herein called "deficiency") to Landlord monthly on the
days on which the Rent would have been payable under this Lease if this Lease
were still in effect, and Landlord shall be entitled to recover from Tenant each
monthly deficiency as the same shall arise.

The foregoing remedies may be pursued severally or jointly.  No exercise by
Landlord of the foregoing remedies, and no expiration or termination of this
Lease or summary proceedings, abandonment or vacancy effected pursuant to this
Article  20, shall relieve Tenant of its liability and obligation under this
Lease, whether or not the Premises shall be relet.  In any such event Tenant
shall pay Landlord the Base Rent, Tenant's Proportionate Share of Operating and
Tax Expenses, Additional Rent and other charges required Tenant's to be paid by
Tenant up to the time of such event.

(4)  At Landlord's election, Landlord shall be entitled to recover as damages
caused by such breach of the provisions of this Lease in lieu of sums becoming
due under Section 20(B)(3): either (a) an amount equal to the difference, if
any, between (i) the Rent reserved hereunder for the unexpired portion of the
Term, together with all Reletting Costs and (ii) the fair rental value of the
Premises for the balance of the Term which Tenant proves can be realized from
reletting, both discounted at the rate of six percent (6%) per annum to their
then present worth. Said damages shall be due and payable to Landlord
immediately upon breach of this Lease as

                                      -30-
<PAGE>

provided in this Article. Such sum shall be payable in addition to and not in
lieu of amounts due under Section 20(B)(1) above and any amounts owed pursuant
to the terms of this Lease for any period prior to termination. In determining
the fair rental value of the Premises, the rental realized by any reletting
shall be deemed prima facie evidence thereof, or (b) an amount equal to twelve
(12) months of Base Rent.


21.  BANKRUPTCY:

If at any time during the Term of this Lease, a petition shall be filed, either
by or against Tenant, in any court or pursuant to any Federal, State or
municipal statute whether in bankruptcy, insolvency, for the appointment of a
receiver, involving Tenant's business or property or because of any general
assignment made by Tenant of Tenant's property for the benefit of Tenant's
creditors, then immediately upon the happening of any such event, in addition to
any other remedy available to Landlord hereunder and without any entry or other
act by Landlord, this Lease, subject to the time limitations set forth in
Section 20.(A)(4) at Landlord's option, shall cease and come to an end with the
same force add effect as if the date of the happening of any such event were the
date herein fixed for the expiration of the Term.  It is further stipulated and
agreed that in the event of termination of the Term by the happening of any such
event, Landlord shall forthwith, upon such termination, any other provisions of
this Lease to the contrary notwithstanding, become entitled to recover as and
for liquidated damages caused by such breach of the provisions of this Lease, an
amount equal to the difference between (a) the then present cash value of the
future Rent reserved hereunder for the unexpired portion of the Term, and (b)
the then cash rental value of the Premises for the balance of the Term, unless
the statute which governs shall limit the amount of such claim capable of being
so proved, in which case Landlord shall be entitled to prove as and for
liquidated damages an amount equal to that allowed by or under any such statute.
Said damages shall be due and payable to Landlord immediately upon breach of
this Lease as provided in this Article.  In making any such computation, the
then cash rental value of Premises shall be deemed prima facie to be the rental
realized upon any reletting, if such reletting can be accomplished by Landlord
within a reasonable time after such termination of this Lease, and the then
present cash value of the future rents reserved hereunder to Landlord for the
unexpired portion of the Term shall be deemed to be such sum, if invested at six
percent (6%) simple interest, as will produce the future rent over the period of
time in question.  The provisions of this Article of this Lease shall be without
prejudice to Landlord's right to prove in full damages for Rent accrued prior to
termination of this Lease, but not paid.  This provision of this Lease shall be
without prejudice to any rights given Landlord by any pertinent statute to prove
further any amounts allowed thereby.


22. LANDLORD DEFINED:

A.   Definition
     ----------

                                      -31-
<PAGE>

The term "Landlord" as used in this Lease insofar as covenants or obligations on
the part of Landlord are concerned, shall be limited to mean and include only
the owner or owners at the time in question of the fee of the Premises.
Landlord may assign, transfer, or sell this Lease in its sole and absolute
discretion.  In the event of any transfer of title to such fee, Landlord herein
named (and in the case of any subsequent transfers or conveyances, the then
grantor) shall automatically be freed and relieved from and after the date of
such transfer or conveyance of all liability as respects the performance of any
covenants or obligations on the part of Landlord contained in this Lease
thereafter to be performed, provided that any funds in the hands of such
Landlord, or the then grantor, at the time of such transfer in which Tenant has
an interest, shall be turned over to the grantee, and any amount then due and
payable to Tenant by Landlord, or the then grantor under any provisions of this
Lease, shall be paid to Tenant.

B.   Limitations of Assets Liable for Collection of Judgment
     -------------------------------------------------------

If Landlord or any successor in interest be an individual, corporation, limited
liability company, limited liability partnership, joint venture, tenancy in
common, limited or general partnership, or other unincorporated aggregate of
individuals or a mortgagee (all of which are herein referred to individually and
collectively as "Landlord"), then anything elsewhere in this Lease to the
contrary notwithstanding, Tenant shall look solely to the estate and property of
such Landlord in the Building of which the Premises are a part for the
satisfaction of Tenant's remedies for the collection of a judgment (or other
judicial process) requiring the payment of money by Landlord in the event of any
default or breach by Landlord with respect to any of the terms, covenants, and
conditions of the Lease to be observed and/or performed by Landlord, and no
other property or assets of such Landlord, or of any shareholder, officer,
director, managing agent, member or partner of Landlord, shall be subject to
levy, execution, or other enforcement procedure for the satisfaction of Tenant's
remedies.


23.  RECORDING PROHIBITED:

Tenant shall not record this Lease, or a memorandum or notice hereof, in any
form.


24.  PREVAILING PARTY IN LEGAL PROCEEDINGS:

In the event any action is commenced for any breach of any covenant, condition,
or agreement herein contained, the prevailing party in such action shall be
entitled to receive all costs incurred in such action, including without
limitation, all reasonable attorneys' fees.


25.  SEVERABILITY:

If  any clause or provision of this Lease is or becomes illegal, invalid, or
unenforceable because of present or future laws or any rule or regulation or any
governmental body or entity, effective

                                      -32-
<PAGE>

during its Term, the intention of the parties hereto is that the remaining parts
of this Lease shall not be affected thereby unless such invalidity is, in the
sole determination of Landlord, essential to the rights of both parties in which
event Landlord has the right to terminate this Lease on written notice to
Tenant.


26.  HOLDING OVER:

If after the expiration of this Lease, Tenant shall remain in possession of the
Premises and continue to pay rent, without any written agreement as to such
holding, then such holding shall be deemed and taken to be a holding upon a
tenancy from month to month, subject to all the terms and conditions hereof on
the part of Tenant to be observed and performed and at a monthly rental
equivalent to one hundred fifty percent (150%) of the monthly installments of
Base Rent, and Tenant's Proportionate Share of Operating and Tax Expenses
hereinabove provided for during the year immediately preceding, all of which
shall be payable in advance on the first day of each calendar month.  In the
event Tenant holds over for any reason, and Landlord or Tenant's successor in
occupancy suffers any cost, expense, or damage by reason of such holding over,
Tenant agrees to indemnify Landlord and the said successor in occupancy for all
such costs, expenses, or damages including reasonable attorney's fees.  Such
indemnification payment shall be in addition to the Rent obligation assumed by
Tenant hereunder.


27.  RE-ENTRY BY LANDLORD:

Tenant hereby expressly waives, so far as permitted by law, the service of any
notice of intention to re-enter provided for in any statute, and except as is
herein otherwise provided, Tenant, for and on behalf of itself and all persons
claiming through or under Tenant (including any leasehold mortgagee or other
creditor), also waives any and all right of redemption of re-entry or
repossession in case Tenant shall be dispossessed by a judgment or by warrant of
any court or judge or in case of re-entry or repossession by Landlord or in case
of any expiration or termination of this Lease.  The terms "enter", "re-enter,"
"entry" or "re-entry" as used in this Lease are not restricted to their
technical legal meanings.


28.  NO WAIVER:

No failure by Landlord to insist upon the strict performance of any agreement,
term, covenant or condition hereof or to exercise any right or remedy consequent
upon a breach thereof, and no acceptance of full or partial Rent during the
continuance, of any such breach, shall constitute a waiver of any such breach or
of such agreement, term, covenant or condition.  No agreement, term, covenant or
condition hereof to be performed or complied with by Tenant, and no breach
thereof, shall be waived, altered or modified except by a written instrument
executed by Landlord.  No waiver of any breach shall affect or alter this Lease,
but each and every agreement,

                                      -33-
<PAGE>

term, covenant and condition shall continue in full force and effect with
respect to any other then existing or subsequent breach thereof.


29.  OTHER REMEDIIES:

In the event of any breach or threatened breach by Tenant of any of the
agreements, terms, covenants or conditions contained in this Lease, Landlord
shall be entitled to enjoin such breach or threatened breach and shall have the
right to invoke any right and remedy allowed at law or in equity or by statute
or otherwise as though re-entry, summary proceedings, and other remedies were
not provided for in this Lease.

Landlord may, but shall not be obligated to, cure, at any time upon ten (10)
days' notice or without notice in case of emergencies, any default(s) by Tenant
under this Lease, and Tenant shall pay to Landlord on demand all costs and
expenses incurred by Landlord in curing such default(s), including, without
limitation, court costs and attorneys' fees and disbursements in connection
therewith, together with interest on the amount of costs and expenses so
incurred at the lesser of (i) eighteen percent (18%) per annum or (ii) the
maximum rate then permissible under Connecticut law, until paid.

Each right and remedy provided for in this Lease shall be cumulative and shall
be in addition to every other right or remedy provided for in this Lease or now
or hereafter existing at law or in equity or by statute or otherwise, and the
exercise or beginning of the exercise by Landlord or Tenant of any one or more
of the rights or remedies provided for in this Lease or now or hereafter
existing at law or in equity or by statute or otherwise shall not preclude the
simultaneous or later exercise by the party in question of any or all other
rights or remedies provided for in this Lease or now or hereafter existing at
law or in equity or by statute or otherwise.


30.  NOTICE TO MORTGAGEES:

Tenant  agrees that in the event Tenant shall claim any event of default or non-
performance hereunder on the part of Landlord or shall claim that there exist
any circumstances whatsoever which give rise (or with the passage of time would
give rise) to a right of termination on the part of Tenant hereunder, Tenant
shall give immediate written notice of such event or such circumstances to all
mortgagees of Landlord of which Tenant has been notified, in addition to and
separate from any notice required to be given to Landlord hereunder.  Tenant
further agrees that if Landlord shall have failed to cure such default within
the time provided for in this Lease, then the holders of mortgages shall have an
additional thirty (30) days within which to cure such default or if such default
cannot be cured within that time, then such additional time as may be necessary
if within such thirty (30) days, any holder of a mortgage or deed of trust has
commenced and is diligently pursuing the remedies necessary to cure such default
(which may include the commencement of foreclosure proceedings, if necessary, to
effect such cure), in

                                      -34-
<PAGE>

which event this Lease shall not be terminated while such remedies are being so
diligently pursued.


31.  ENVIRONMENTAL LAWS:

A.   Compliance:
     ----------

With respect to Tenant's use of the Premises, the Building and the Property,
Tenant shall at all times, at its own cost and expense, comply with all federal,
state, and local laws, ordinances, regulations, and standards relating to the
use, analysis, production, storage, sale, disposal, or transportation of any
"hazardous materials," "hazardous waste", or "hazardous substances,"
(collectively referred to herein as "Hazardous Substances") as such terms are
defined in any of the following: the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended, 42 U.S.C. Section 9601, et
                                                                            --
seq. ("CERCLA"); The Clear Air Act, as amended, 42 U.S.C. (S)7401, et seq.; The
---                                                                -- ---
Federal Water Pollution Control Act (Clean Water Act), 33 U.S.C. (S)1251, et
                                                                          --
seq.; The Occupational Safety and Health Act, 29 U.S.C. (S)51, et seq.; The
---                                                            -- ---
Resource Conservation and Recovery Act, 42 U.S.C. (S)6901, et seq.; The
                                                           -- ---
Hazardous Materials Transportation Act, 49 U.S.C. Section 1802; The Toxic
Substances Control Act, 15 U.S.C. Section 2601, et seq.; and/or any other
                                                -- ---
federal, state or local environmental law, ordinance, rule or regulation and the
regulations adopted and publications promulgated pursuant to any of said Acts
(collectively the "Hazardous Substance Laws"), including oil or petroleum
products or their derivatives, solvents, PCB's, explosive substances, asbestos,
radioactive materials or waste, and any other toxic, ignitable, reactive,
corrosive, contaminating, or pollution materials which are now or in the future
subject to any governmental regulations.

Tenant shall not generate, store, or dispose of any Hazardous Substances in or
on the Premises, the Building or the Property.  Tenant shall not take any
remedial action in response to the presence or release of any Hazardous
Substances on or about the Premises, the Building or the Property without first
giving written notice of the same to Landlord.  Tenant shall not enter into any
settlement agreement, consent decree, or other compromise with respect to any
claims relating to any Hazardous Substances in any way connected with the
Property without Landlord's prior written consent, which consent may be withheld
or conditioned in Landlord's sole and absolute discretion, and without affording
Landlord the opportunity to participate in any such proceedings.

All costs and expenses incurred by Landlord in connection with any environmental
audit shall be paid by Landlord (and may be included in Operating Expenses),
except that if any such environmental audit shows that Tenant has failed to
comply with the provisions of this Article, or that the Property (including
surrounding soil and any underlying or adjacent groundwater) have become
contaminated due to the operations or activities in any way attributable to
Tenant, then all of the costs and expenses of such audit shall be paid by Tenant
on demand, as Additional Rent.

                                      -35-
<PAGE>

Tenant shall immediately notify Landlord upon the receipt by Tenant of any
"Notice," as hereinafter defined, of any violation of the Hazardous Substance
Laws.  "Notice" shall mean any summons, citation, directive, order, claim,
litigation, investigation, proceeding, judgment, letter or other communication,
written or oral, actual or threatened, from the United States Environmental
Protection Agency ("US EPA") or other federal, state or local agency or
authority or any other entity or any individual, concerning any intentional or
unintentional act or omission which has resulted or which may result in the
releasing of Hazardous Substances into the waters or onto the land of the State
or commonwealth in which the Property is located or into the "environment" as
such term is defined in CERCLA or into waters outside of the jurisdiction of the
State or commonwealth in which the Property is located, from or on the Premises,
the Building, or the Property or any portion thereof, and shall include the
imposition of any lien on the Premises, the Building, or the Property or any
portion thereof, pursuant to Hazardous Substance Laws or any violation of
federal, state or local environmental laws, ordinances, rules, regulations,
government actions, orders or permits, or any knowledge, after due inquiry and
investigation, or of any facts which could give rise to any of the above.

In the event Tenant fails to comply with the requirements of any of the
Hazardous Substance Laws, it shall be deemed an event of default of this Lease
and Landlord may, at its election, but without the obligation so to do, give
such notices or cause such work to be performed at the Premises, the Building,
or the Property, or take any and all other actions as Landlord deems necessary,
as shall cure said failure of compliance, and any amounts paid as a result
thereof, together with interest thereon at lesser of (i) eighteen percent (18%)
per annum or (ii) the maximum rate permissible under Connecticut Law for any
period during which there is such an event of default, from the date of payment
by Landlord, shall be immediately due and payable by Tenant to Landlord, as
Additional Rent, or Landlord, by the payment of any assessment, claim, or
charge, may, if it sees fit, be thereby subrogated to the rights of the
governmental agencies having jurisdiction over such matters.

B.   Indemnity:
     ---------

In the event of any breach of this Article 31, Tenant agrees to defend,
indemnify, and hold harmless Landlord, its successors and assigns from and
against any and all liabilities, losses, damages, costs, expenses (including,
without limitation reasonable attorneys' fees and expenses), civil and/or
criminal penalties, causes of action, suits, claims, demand, or judgments of any
nature arising out of or in connection with (i) the presence of any Hazardous
Substances on or in the Premises, or the release of any Hazardous Substances
therefrom or from any property of Tenant located on or in the Building or the
Property; (ii) any failure by Tenant to comply with the terms of any order
issued by the US EPA, or any other federal, state, or municipal department or
agency having regulatory authority over environmental matters, with regard to
the Premises; and (iii) any lien or claim imposed under any Hazardous Substance
Laws.  The provisions of this Section 3l.B. shall survive the expiration or
earlier termination of this Lease.


32. COMPLIANCE WITH LAW:

                                      -36-

<PAGE>

A.   Tenant, at Tenant's expense, shall comply promptly with the laws,
ordinances, rules, regulations and orders of all governmental authorities in
effect from time to time during the Term that shall impose any duty on Tenant
with respect to Tenant's use of the Premises, including, without limitation, the
Americans with Disabilities Act ("ADA") and the Federal Occupational Safety and
Health Act of 1970, and will obtain any and all licenses and permits necessary
for any such use.  Following completion of the Construction Work, Tenant shall
not be required to make any alterations in or to the Premises in order to comply
with the foregoing, unless such alterations shall be necessitated or occasioned,
in whole or in part (i) by Tenant's obligations under the ADA as set forth in
subsection (B), (ii) by the use or manner of use of the Premises by Tenant, (i)
by reason of a breach of any of Tenant's covenants, warranties or agreements
hereunder, or (iv) by the willful misconduct or negligence of Tenant, or any
person claiming through or under Tenant, or any of their servants, employees,
contractors, agents, visitors or licensees.

B.   Tenant represents, warrants and agrees that: (i) the placement of Tenant's
furniture, fixtures and equipment within the Premises, and (ii) all of Tenant's
Leasehold Improvements or alterations to the Premises undertaken by Tenant will
comply, to the extent necessary, with the ADA.  Tenant agrees to indemnify and
hold Landlord harmless from any claims, losses, costs, damages or other expenses
(including, without limitation, reasonable attorneys' fees) arising from any
breach of the foregoing warranty and covenants.


33.  RIGHT OF FIRST OFFER:

If at any time during the first two (2) Lease Years of this Lease, Landlord
decides to seek offers to lease (i) all or any part of the space remaining on
the fifth (5th) floor of the Building following the leasing of space remaining
on said fifth floor to any other tenant after the execution of this Lease, or in
the alternative at Landlord's discretion, (ii) a block of space equal to or
greater than 5,000 rentable square feet elsewhere in the Building, Landlord
shall provide Tenant with written notice of the terms under which Landlord will
seek such offers ("Landlord's Offer").  Within fourteen (14) days following its
receipt of Landlord's Offer, Tenant shall have the right to accept the same by
written notice to Landlord.  Within thirty (30) days following Tenant's written
notice of acceptance, Landlord and Tenant shall enter into an amendment of this
Lease incorporating the terms of Landlord's Offer.  In the event Tenant either
rejects Landlord's Offer or fails to notify Landlord of its acceptance of the
same within said fourteen (14) day period, the right of first offer shall
terminate.


34.  MISCELLANEOUS:

A.   Taxes
     -----

                                      -37-
<PAGE>

Tenant, at all times, shall be responsible for and shall pay, before
delinquency, all municipal, county, state, or federal taxes which may be levied,
imposed or assessed against Tenant's personal property, its leasehold interest,
its right to occupy the Premises, or the Rent.  If any governmental authority
requires that a tax, other than the ad valorem taxes above mentioned, be paid by
Tenant, but collected by Landlord, for and on behalf of said governmental
authority, and from time to time forwarded by the Landlord to said governmental
authority, the same shall be paid by Tenant to Landlord and be collectable by
Landlord and for the purpose of enforcing payment thereof shall be deemed
Additional Rent hereunder, payable monthly.


B.   Accord and Satisfaction:
     -----------------------

No payment by Tenant or receipt by Landlord of any lesser amount than the amount
stipulated to be paid hereunder shall be deemed other than on account of the
earliest stipulated Rent; nor shall any endorsement or statement on any check or
letter be deemed an accord and satisfaction, and Landlord may accept any check
or payment without prejudice to Landlord's right to recover the balance due or
to pursue any other remedy available to Landlord.

C.   No Representations by Landlord:
     -------------------------------

Neither Landlord nor any agent or employee of Landlord has made any warranties,
representations or promises with respect to the Building or the Premises except
as herein expressly set forth herein.

D.   End of Term:
     -----------

At the expiration or sooner termination of the Term, Tenant shall quit and
surrender to Landlord the Premises, broom clean and in good order and condition,
ordinary wear and tear and damage by fire and any other casualty excepted.  At
such expiration or sooner termination Tenant shall remove all personal property
of Tenant except as provided in Section 5 hereof, and Tenant shall repair all
damage to the Premises or Building caused by such removal and restore the
Premises to the condition in which they were prior to the installation of the
items so removed.  Any personal property of the Tenant which shall remain in or
upon the Premises after the expiration of the Term or sooner termination thereof
and the removal of Tenant from the Premises may, at the option of Landlord, be
deemed to have been abandoned, and either may be retained by Landlord as its
property or may be disposed of in such manner as Landlord may see fit.  If the
Premises are not surrendered as and when aforesaid, Tenant shall indemnify
Landlord against loss or liability resulting from the delay by Tenant in so
surrendering the Premises including, without limitation, any claims made by any
succeeding occupant founded on such delay.  Tenant's obligations under this
Section 32.D. shall survive the expiration or sooner termination of the Term.

E.   Waiver of Jury Trial and Right to Counterclaim/Prejudgment Remedy Waiver
     ------------------------------------------------------------------------

                                      -38-
<PAGE>

     (a)  Landlord and Tenant shall and they hereby do waive trial by jury in
          any action, proceeding or counterclaim brought by either of the
          parties hereto against the other on any matters arising out of or in
          any way connected with this Lease, the relationship of Landlord and
          Tenant, Tenant's use or occupancy of the Premises, and any emergency
          or other statutory remedy.  Tenant further agrees that it shall not
          interpose any counterclaim(s) in a summary proceeding or in any action
          based on holdover or non-payment of Rent.

     (b)  TENANT, FOR ITSELF AND FOR ALL PERSONS CLAMING THROUGH OR UNDER IT,
          HEREBY ACKNOWLEDGES THAT THIS LEASE CONSTITUTES A COMMERCIAL
          TRANSACTION AS SUCH TERM IS USED AND DEFINED IN SECTION 52-278(A) OF
          THE CONNECTICUT GENERAL STATUTES, OR ITS SUCCESSOR PROVISIONS IF
          AMENDED, AND HEREBY EXPRESSLY WAIVES ANY AND ALL RIGHTS WHICH ARE OR
          MAY BE CONFERRED UPON TENANT BY SAID ACT TO ANY NOTICE OR HEARING
          PRIOR TO A PREJUDGMENT REMEDY UNDER SECTIONS 52-278(A) TO 52-278(G),
          OR THEIR SUCCESSOR PROVISIONS IF AMENDED, INCLUSIVE OF SAID STATUTES.
          SUCH WAIVER IS INTENDED AS A WAIVER IN ACCORDANCE WITH SECTION 52-
          278(F) OR ITS SUCCESSOR PROVISIONS IF AMENDED, OF SAID STATUTES.

F.  Intentionally Omitted.
    ---------------------

G.  Unavoidable Delays:
    -------------------

It is understood and agreed that with respect to any service to be furnished or
obligations to be performed by Landlord for Tenant that in no event shall
Landlord be liable for failure to furnish or perform the same when prevented
from doing so by strike, lockout, breakdown, accident, supply, or inability by
the exercise of reasonable diligence to obtain supplies, parts, or employees
necessary to furnish such service or meet such obligation; or because of war or
other emergency; or for any cause beyond Landlord's reasonable control; or for
any cause due to any act or omission of Tenant or its agents, employees,
licensees, invitees, or any persons claiming by, through, or under Tenant
(individually and collectively referred to herein as "force majeure").

H.  Brokerage:
    ----------

Each party represents to the other that (i) it has not dealt with any broker,
agent or other intermediary who is or may be entitled to be paid a broker
commission or finder's fee in connection with this Lease, except for
Insignia/ESG ("Landlord's Broker") and Sentry Commercial Real Estate Services,
Inc. ("Tenant's Broker"); and (ii) there are no claims for brokerage commissions
or finder's fees in connection with this Lease, except as to Landlord's Broker
and Tenant's Broker.  Landlord and Tenant acknowledge that Landlord shall pay a
commission or finder's fee only to Landlord's Broker pursuant to a separate
agreement between

                                      -39-
<PAGE>

Landlord and Landlord's Broker. Landlord shall have no obligation or liability
of any nature whatsoever to pay any commission, broker's fee or otherwise to
Tenant's Broker. Tenant's Broker shall be paid by Landlord's Broker. Each party
agrees to indemnify the other and hold it harmless from all liabilities arising
from breach of the representations stated above. The representations and
obligations contained in this subparagraph 34(H) shall survive the termination
of this Lease.

I.  Successors and Assigns:
    ----------------------

The provisions of this Lease, except as herein otherwise specifically provided
shall extend to, bind and inure to the benefit of the parties hereto and their
respective personal representatives, heirs, successors and permitted assigns.

J.  Consents and Approvals:
    ----------------------

In the event that Tenant shall seek the approval by or consent of Landlord and
Landlord shall fail or refuse to give such consent or approval, Tenant shall not
be entitled to any damages for any withholding or delay of such approval or
consent by Landlord, it being intended that Tenant's sole remedy shall be an
action for injunction or specific performance and that said remedy of any action
for injunction or specific performance shall be available only in those cases
where Landlord shall have expressly agreed in writing not to unreasonably
withhold or delay its consent.

K.  Interpretation:
    ---------------

Irrespective of the place of execution or performance, this Lease shall be
governed by and construed in accordance with the laws of the State of
Connecticut.  If any provision of this Lease or the application thereof to any
person or circumstances shall, for any reason and to any extent, be invalid or
unenforceable, the remainder of this Lease and the application of that provision
to other persons or circumstances shall not be affected but rather shall be
enforced to the extent permitted by law.  The table of contents, captions,
headings and titles in this Lease are solely for convenience of reference and
shall not affect its interpretation.  This Lease shall be construed without
regard to any presumption or other rule requiring construction against the party
causing this Lease to be drafted.  If any words or phrases in this Lease shall
have been stricken out or otherwise eliminated, whether or not any other words
or phrases have been added, this Lease shall be construed as if the words or
phrases so stricken out or otherwise eliminated were never included in this
Lease and no implication or inference shall be drawn from the fact that said
words or phrases were so stricken out or otherwise eliminated.  Each covenant,
agreement, obligation or other provision of this Lease shall be deemed and
construed as a separate and independent covenant of the party bound by,
undertaking or making same, not dependent on any other provision of this Lease
unless otherwise expressly provided.  All terms and words used in this Lease,
regardless of the number or gender in which they are used, shall be deemed to
include any other number and any other gender as the context may require.

                                      -40-
<PAGE>

L.  Authority:
    ---------

Each person executing this Lease warrants to the other party that it has full
right and authority to enter into this Lease and that each person signing on
behalf of such party is authorized to do so.

M.  Complete Agreement:
    ------------------

There are no representations, agreements, arrangements or understandings, oral
or written, between the parties relating to the subject matter of this Lease
which are not fully expressed in this Lease.  This Lease cannot be changed or
terminated orally or in any manner other than by a written agreement executed by
both parties.

                                    LANDLORD:

Witnessed by:                       LONG WHARF DRIVE, LLC


                                     By:
----------------------------            ----------------------------
                                        Its:
                                            ------------------------
----------------------------


STATE OF CONNECTICUT  )
                      ) ss.:
COUNTY OF             )
          ----------

          On this the    day of             , 1999 before me           , the
                      --        ------------                 ---------
undersigned officer, personally appeared Barbara E. Hampton, who acknowledged
herself to be the            of Long Wharf Drive, LLC and that she, as such
                  ----------
          and being authorized to do so, executed the foregoing instrument for
---------
the purposes therein contained.

     IN WITNESS WHEREOF, I hereunto set my hand and official seal.



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

                                      -41-
<PAGE>

Witnessed by:                           TENANT:

                                        dsl.net, incorporated

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



STATE OF CONNECTICUT  )
                      ) ss.:
COUNTY OF             )
          ----------

          On this the    day of             , 1999 before me           , the
                      --        ------------                 ---------
undersigned officer, personally appeared          , who acknowledged
                                         ---------
himself/herself to be the            of             and that he/she, as such
                          ----------    -----------
        , being authorized to do so, executed the foregoing instrument for the
--------
purposes therein contained.

     IN WITNESS WHEREOF, I hereunto set my hand and official seal.


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

                                      -42-
<PAGE>

                           AMENDMENT NO. 1 TO LEASE

     THIS AMENDMENT NO. 1 TO LEASE is made and entered into as of the 9th day
of June, 1999 between Landlord and Tenant named below.

LANDLORD:      LONG WHARF DRIVE, LLC
               310 Orange Street
               New Haven, CT 06511

TENANT:        dsl.net, incorporated
               545 Long Wharf Drive
               New Haven, CT 06511


BUILDING:      545 Long Wharf Drive
               New Haven, CT 06511


     WHEREAS, Landlord and Tenant executed a lease dated as of February 5, 1999
(the "Lease"), by which Tenant leased 12,078 rentable square feet on the fifth
(5th) floor of the Building (the "Premises"); and

     WHEREAS, Tenant also leases and occupies certain "Temporary Space," as that
term is defined in the Lease; and

     WHEREAS, Tenant wishes to lease an additional 19,422 rentable square feet
of space located on the fifth (5th) floor in the Building (the "Additional
Space"), thereby increasing the size of the Premises to 31,500 rentable square
feet; and

     WHEREAS, Tenant wishes to continue its occupancy of the Temporary Space
until the "Additional Space Commencement Date," as that term is defined below;
and

     WHEREAS, Landlord and Tenant wish to execute an amendment of the Lease
stating, among other things, the new area of the Premises, the annual Base Rent,
the monthly rent installment, and Tenant's Proportionate Share,

     NOW, THEREFORE, the parties to this Amendment No. 1 to Lease, in
consideration of the covenants hereinafter contained and the sum of One Dollar
($1.00) to each party paid by the other, the receipt of which is hereby
acknowledged, I do covenant and agree as follows:

     1.   Unless otherwise stated herein, this Amendment is effective on the day
and year written above.

<PAGE>

                                      -2-

     2.
          (a)  Tenant shall acquire and lease from Landlord the Additional
Space, said Additional Space being shown and designated on the plan attached
hereto as Exhibit A , on the later to occur of (i) June 15, 1999, and (ii) the
date the Additional Space is "Substantially Completed," the later to occur of
said dates being referred to as the "Additional Space Commencement Date." The
Additional Space shall be deemed "Substantially Completed" when Landlord has
completed certain improvements (the "Improvements") as shown on the plans which,
when approved by Landlord, shall be narratively described by title block in
Exhibit B attached hereto and made a part hereof (the "Additional Space
---------
Construction Plans"), as shall be determined by Landlord's project architect or
construction manager, despite the fact that minor or insubstantial details of
construction, decoration or mechanical adjustments remain to be performed,
provided said minor terms can be fully performed within sixty (60) days without
(material) interference with Tenants use of the Additional Space. The
Improvements shall be performed by Landlord, at Tenant's sole cost and expense
as more particularly described in Subparagraph 2(c) below. Tenant's occupancy of
the Additional Space shall be for a term as shall be co-terminous with the
expiration date of the Lease.

          (b)   Landlord will use commercially reasonable efforts to
Substantially Complete the Improvements by June 15, 1999, provided Tenant has
submitted the Additional Space Construction Plans on a timely basis as required
by Landlord and Tenant does not otherwise interfere with Landlord's construction
of the Improvements. Landlord shall have no liability for Landlord's failure to
Substantially Complete the Improvements by June 15, 1999.

          (c)   Tenant's costs ("Tenant's Additional Space Costs") for the
Improvements shall be the contract price paid by Landlord for the construction
of the Improvements and all materials associated therewith, as the same may have
been revised by any change orders, plus the following: (i) permit fees; (ii)
space planning and other design costs; (iii) fees of a third party construction
manager; (iv) fees of architects and engineers in connection with the design of
the Improvements; (v) general contractor profit and overhead; (vi)
administrative fees of Landlord in connection with overseeing the design and
construction of the Improvements; (vii) the cost of installing submeter(s) in
the Additional Space for measuring Tenant's electrical consumption; and (viii)
all other costs and expenses in connection with the design and construction of
the Improvements.

          (d)   Landlord shall provide Tenant an allowance of up to Twelve and
00/100 Dollars ($12.00) per rentable square foot of the Additional Space (the
"Additional Space Improvement Allowance"), to be applied against Tenant's
Additional Space Costs. Within sixty (60) days of Substantial Completion of the
Additional Space, Landlord shall furnish to Tenant a final accounting of
Tenant's Additional Space Costs. To the extent that Tenant's Additional Costs
exceed Ten and 00/100 Dollars ($10.00) per rentable square foot of the
Additional Space but are less than or equal to Twelve and 00/100 Dollars
($12.00) per rentable square foot of the Additional Space (the "Additional Space
Excess Tenant's Costs"), annual Base Rent shall be increased as follows: the
Additional Space Excess Tenant's Costs shall be fully amortized on a straight-
line basis over the remaining initial Term, using an annual interest factor of
ten percent (10%), so as to arrive at a monthly amortization amount (the
"Additional Space Monthly Amortized Allowance Amount"). The preceding sentence
notwithstanding, Tenant shall also remain fully liable and obligated to pay for
all Tenant's Additional Space Costs in excess of Twelve and 00/100 Dollars
($12.00) per rentable square foot of the Additional Space as provided in
subparagraph 2(e) below. The Additional Space Monthly Amortized Allowance Amount
shall be added to the monthly installment of Base Rent and shall be treated as
Base Rent for all purposes of the Lease. Upon determination of the Additional
Space Monthly Amortized Allowance Amount, the parties shall enter into an
amendment to this Lease to establish the increased Base Rent. Any Additional
Space Excess Tenant's Costs arising hereunder and the corresponding increase to
Base Rent shall be in addition to, and not in lieu of, any increase in Base Rent
arising as a result of any "Excess Tenant's Costs" as set forth in subparagraph
5(C)(d) of the Lease.
<PAGE>

                                      -3-

Space Monthly Amortized Allowance Amount, the parties shall enter into an
amendment to this lease to establish the increased Base Rent. Any Additional
Space Excess Tenant's Cost arising hereunder and the corresponding increase to
Base Rent shall be in addition to, and not in lieu of, any insrease in base Rent
arising as a result of any "Excess Tenant's Cost" as set forth in subparagraph
5 (c) (d) of the Lease.

          (e)   If Tenant's Additional Space Costs exceed the Additional Space
Improvement Allowance, then Tenant shall pay Landlord such excess within ten
(10) days after receipt of such final accounting, as Additional Rent.

          (f)   If Tenant's Additional Space Costs are less than the Additional
Space Improvement Allowance and "Tenant's Costs," as that term is defined in
subparagraph 5(C)(a) of the Lease (for the construction of the original Premises
as contemplated in paragraph 5 of the Lease) are greater than the "Improvement
Allowance," as that term is defined in subparagraph 5(C)(b) of the Lease, then
any unused portion of the Additional Space Improvement Allowance shall be
applied by Landlord toward the difference between Tenant's Costs and the
Improvement Allowance.  For example, if Tenant's Costs equal $14.00 per rentable
square foot of the original Premises (with the Improvement Allowance being
capped at $12.00 per rentable square foot of the original Premises) and Tenant's
Additional Space Costs equal $10.00 per rentable square foot of the Additional
Space (with the Additional Space Improvement Allowance being capped at $12.00
per rentable square foot of the Additional Space), then Landlord shall apply the
balance of the Additional Space Improvement Allowance (said balance being $2.00
per rentable square foot of the Additional Space) toward Tenant's Costs. Tenant
shall remain solely liable for any deficiency remaining for Tenant's Costs. If
any surplus exists from the Improvement Allowance and/or the Additional Space
Improvement Allowance after each has been applied toward Tenant's Costs and
Tenant's Additional Space Costs, as the case may be, the same shall be retained
by Landlord. If the cross-funding contemplated by this subparagraph 2(f) is
utilized, then the corresponding increase to Base Rent set forth in subparagraph
5(C)(d) of the Lease and in subparagraph 2(d) shall be calculated pursuant to
subparagraph 2(g) below.

          (g)   Pursuant to subparagraph 2(f) above, if the quotient obtained by
dividing the sum of Tenant's Costs and Tenant's Additional Space Costs by the
size of the entire Premises (i.e. the entire Premises consisting of 31,500
rentable square feet) is less than Ten and 00/100 Dollars ($10.00) per rentable
square foot of the entire Premises, then the increase(s) to Base Rent set forth
in subparagraph 5(C)(d) of the Lease and subparagraph 2(d) of this Amendment
shall be inapplicable.  For example, although the Improvement Allowance actually
disbursed toward Tenant's Costs may be in excess of $10.00 per rentable square
foot of the original Premises (which would otherwise trigger the increase to
Base Rent), if Tenant's Additional Space Costs, and therefore the Additional
Space Improvement Allowance, is a number which, when calculated on a per
rentable square foot of the Additional Space basis, is such that the total
amount of the sum of Tenant's Costs and Tenant's Additional Space Costs result
in an average cost of $10.00 per rentable square foot of the entire Premises or
less, then there shall be no such increase to Base Rent.  Similarly, if,
following any cross-funding contemplated by the provisions of subparagraph 2(f)
above, the average of Tenant's Costs and Tenant's Additional Space Costs are
<PAGE>

                                      -4-

in excess of $10.00 per rentable square foot of the entire Premises, then Base
Rent shall increase per the provisions of subparagraph 5(C)(d) of the Lease and
2(d) herein.

          (h)   Tenant acknowledges and agrees that the Improvement Allowance
contemplated in paragraph 5(C)(b) of the Lease shall apply only to the rentable
square footage of the original Premises, which consist of 12,078 rentable square
feet.  The purpose of this subparagraph 2(h) is to prevent the duplication of
the payment of any improvement allowance for the same area of space.

          (i)   Tenant agrees that it shall continue making all payments of
Base Rent and Additional Rent on the original Premises as provided in the Lease
until the increased rental provisions contained in Section 4 below become
effective.

     3.   Effective on the Additional Space Commencement Date:

          (a)   Subparagraph 1(A) of the Lease is hereby modified by deleting
the term "12,078 rentable square feet" in the second line of said subparagraph,
and inserting the term "31,500 rentable square feet" in lieu thereof.

          (b)   Tenant shall be required to pay Tenant's share of all
Electricity Charges serving the Building. For purposes of this subparagraph
3(b), Tenant agrees that its share shall be 11.80% with respect to its
obligation for the payment of said Electricity Charges. The intent of the
preceding sentence is to provide that although "Tenant's Proportionate Share"
shall not be increased for a period of ninety (90) days after the Additional
Space Commencement Date as provided in Section 4 below, with respect to Tenant's
payments of "Tenant's Proportionate Share of Operating and Tax Expenses," as
that term is defined in the Lease, Tenant's Proportionate Share shall
nevertheless be increased immediately on the Additional Space Commencement Date
with respect to all Electricity Charges for the Building, regardless of whether
the same are ordinarily included in Operating Expenses.

          (c)   The number of parking spaces allocated to Tenant shall be
proportionately increased in accordance with the parking ratio requirements set
forth in Paragraph l(B).

     4.   Effective as of that date which is ninety (90) days following the
Additional Space Commencement Date:

          (a)   The paragraph entitled "Base Rent" in Paragraph 3 of the Lease
is hereby deleted in its entirety and replaced with the following:

                "Base Rent: The Base Rent payable during the initial Term shall
     be Four Hundred Forty-One Thousand and 00/100 Dollars ($441,000.00) per
     annum (based on a per rentable square foot per annum rate of $14.00), which
     shall be payable in advance, in equal monthly installments of Thirty-Six
     Thousand Seven Hundred Fifty and 00/100 Dollars ($36,750.00)."

<PAGE>

                                      -5-

          (b)   The paragraph entitled "Tenant's Proportionate Share" in
Paragraph 3 is hereby modified by deleting the term "4.52%" and inserting the
term "11.80%" in lieu thereof.

     5.   Commencing as of March 1, 1999, the "Temporary Space" as defined in
Paragraph 2(A) of the Lease, is hereby modified to include an additional 1,500
rentable square feet, such that the Temporary Space shall consist of a total of
4,000 rentable square feet, as shown on "Exhibit" A-3 annexed hereto and made a
                                                  ---
part hereof. Further, as of March 1, 1999, the second paragraph of Paragraph
2(E) of the Lease is hereby deleted in its entirety and replaced with the
following:

          "Commencing March 1, 1999 and continuing on the first day of each
     calendar month through and including the Additional Space Commencement Date
     (the "Temporary Space Term"), in addition to and not in lieu of Tenant's
     other obligations under this Lease, Tenant shall pay to Landlord, in the
     manner provided in Section 3 below, for its use and occupancy of the
     Temporary Space, Base Rent in the amount of Four Thousand Six Hundred
     Sixty-Six and 67/100 Dollars ($4,666.67). Tenant shall also be responsible
     during the Temporary Space Term for payment of its Proportionate Share of
     Operating and Tax Expenses as defined below, except that Tenant's
     proportionate share of such costs for Tenant's use and occupancy of the
     Temporary Space, shall be 1.50%.  If Tenant fails to vacate the Temporary
     Space by the Additional Space Commencement Date, the same shall constitute
     an event of default under this Lease and, in addition to the other rights
     afforded Landlord hereunder, the provisions of Section 26 hereof shall
     apply to such holdover."

     6.   Effective as of the date of this Amendment, Paragraph 4 of the Lease
entitled "Letter of Credit" is hereby modified by deleting the fifth (5th)
sentence in its entirety, which sentence defines the term "Required Amount," and
inserting the following sentence in lieu thereof:

          "As used herein, the term "Required Amount" shall mean (a)
     $517,418.37, for the period from the Commencement Date to and including the
     day immediately preceding the first (lst) anniversary of the Commencement
     Date, (b) $413,934.70, for the period from the first anniversary of the
     Commencement Date to and including the day immediately preceding the second
      2nd  anniversary of the Commencement Date, (c) $310,451.03, for the period
     from the second anniversary of the Commencement Date to and including the
     day immediately preceding the third (3rd) Anniversary of the Commencement
     Date, (d) $206,967.36, for the period from the third anniversary of the
     Commencement ]Date to and including the day immediately preceding the
     fourth (4th) Anniversary of the Commencement Date, and (c) $103,483.60,
     for the period from the fourth (4th) anniversary of the Commencement Date
     to and including the day immediately preceding the fifth (5th) anniversary
     of the Commencement Date.

     7.   Effective as of February 5, 1999, Paragraph 5(C)(d) of the Lease is
hereby modified by deleting the word "If" from the first line of said section
and inserting in lieu thereof the phrase "To the extent that".  Further, the
following is hereby added after the first sentence of said section: "The
preceding sentence notwithstanding, Tenant shall also remain fully liable and
<PAGE>

                                      -6-

obligated to pay for all Tenant's Costs in excess of Twelve and 00/100 Dollars
($12.00) per rentable square foot of the Premises as provided in subparagraph
5(C)(c) above."

     8.   Subitem "(i)" of Paragraph 33 of the Lease is hereby deleted in its
entirety.

     9.   Each party represents to the other that (i) it has not dealt with any
broker, agent or other intermediary who is or may be entitled to be paid a
broker commission or finder's fee in connection with this Amendment No. 1 to
Lease, except for Insignia/ESG ("Landlord's Broker") and Sentry Commercial Real
Estate Services, Inc. ("Tenant's Broker"); and (ii) there are no claims for
brokerage commissions or finder's fees in connection with this Amendment, except
as to Landlord's Broker and Tenant's Broker.  Landlord acknowledges that any
commission or finder's fee due to the Broker(s) in connection with this Lease
shall be the sole obligation of Landlord.  Each party agrees to indemnify the
other and hold it harmless from all liabilities arising from breach of the
representations stated above.  The representations and obligations contained in
this Section 9 shall survive the termination of this Amendment.

     10.  Except as set forth above, the Additional Space shall be added to the
Premises for the remainder of the Term on the Additional Space Commencement Date
and shall be subject to all of the terms and conditions of the Lease.

     11.  Tenant hereby represents and warrants to Landlord that "dsl.net,
incorporated," "DSL.net, Inc." and "DSL.NET, INC." are one and the same entity.

     12.  As of March 1, 1999, Exhibit A-3 attached hereto and made a part
                               -----------
hereof is hereby substituted for and shall replace, for all purposes, Exhibit A-
                                                                      ---------
3 originally attached to and made a part of the Lease.
-

     13.  Except as modified by this Amendment No. I to Lease, the terms and
provisions of the Lease are hereby confirmed and ratified, and that instrument
shall remain in full force and effect as modified herein.
<PAGE>

                                      -7-

     IN WITNESS WHEREOF, Landlord and Tenant have signed this Amendment No. 1 to
Lease as of the day and year first above written.



SIGNED, SEALED, AND DELIVERED
IN THE PRESENCE OF:                    LANDLORD

                                       LONG WHARF DRIVE, LLC


______________________________         By:_______________________________

______________________________         Its


                                       TENANT

                                       dsl.net, incorporated


______________________________         By:_______________________________

______________________________         Its Authorized Signatory