<PAGE>

                                 AMENDMENT TO
               SUBLEASE AND ENVIRONMENTAL CONDITIONING AGREEMENT


     THIS AMENDMENT TO SUBLEASE AND ENVIRONMENTAL CONDITIONING AGREEMENT
("Amendment") is entered into this 27 day of March, 2000 by and between ICG
Telecom Group, Inc., a Colorado corporation ("ICG") f/k/a ICG Access Services,
Inc. and USWATS ("Customer"), a Pennsylvania corporation, with its principal
place of business at 3331 Street Rd, Suite 275 Bensalem, PA 19020.

     WHEREAS, Customer has installed certain telecommunications equipment
("Equipment") which interconnects to ICG's network in the premises located at
180 Grand Ave., Oakland, CA 94612 ("Premises"),

     WHEREAS, ICG and Customer have entered into that certain Sublease and
Environmental Conditioning Agreement dated September, 18, 1995 (the
"Agreement"),

     WHEREAS, ICG and Customer desire to amend certain terms and conditions of
the Agreement.

     NOW, THEREFORE, the following amended terms and conditions shall apply to
the Agreement:

1.   The term of the Agreement is hereby extended from its current expiration of
September 18, 2000 until September 18, 2002.

2.   Effect of Amendment. Except to the extent set forth herein, all of the
     -------------------
other terms and conditions of the Agreement shall remain in full force and
effect.

     IN WITNESS WHEREOF, the parties have caused this Amendment to be executed
by their duly authorized representatives on the day and year first above
written.

ICG TELECOM GROUP, INC.                      USWATS


By: /s/ David. M. Hurtado                    By: /s/ [ILLEGIBLE]^^
   ---------------------------                  ------------------------

Name:   DAVID M. HURTADO                     Name:   [ILLEGIBLE]^^
     -------------------------                    ----------------------

Title:  SENIOR VICE PRESIDENT                Title:  CFO
      ------------------------                     ---------------------

Date:   04 APRIL 00                          Date:   3/27/00
     -------------------------                    ----------------------



            Approved
              ICG
          Real Estate
          [ILLEGIBLE]^^
          -------------


                                                                     Page 1 of 1
<PAGE>

                                     LEASE
                                     -----

     THIS LEASE ("Lease") entered into as of the 14 day of June, 1998, between
BRANDYWINE OPERATING PARTNERSHIP, L.P., a Delaware limited partnership
("Landlord"), and U S Wats, Inc. a New York Company with its principal place of
business at 111 Presidential Blvd., Suite 114, Bala Cynwyd, Pennsylvania 19004
("Tenant").

                                  WITNESSETH
                                  ----------

     In consideration of the mutual covenants herein set forth, and intending to
be legally bound, the parties hereto covenant and agree as follows:

     1.   SUMMARY OF DEFINED TERMS.
          ------------------------

          The parties agree that the following defined terms, as used in this
Lease, shall have the meanings and shall be construed as set forth below:

          (a)  "Building": The Building located at 3331 Street Road, Bensalem
                --------
Pennsylvania 19020.

          (b)  "Project": The Building, the land and all other improvements
                -------
located at Two Greenwood Square.

          (c)  "Premises": Suite No. 275, being a 10,873 rentable square foot
                --------
portion of the 2nd floor of the Building shown on the space plan attached hereto
as Exhibit "A" and made a part hereof.
   ----------

          (d)  "Term": From the Commencement Date for a period of 36 months.
                ----

          (e)  "Fixed Rent":
                ----------

                                                   MONTHLY           ANNUAL
     Months             PER R.S.F.               INSTALLMENTS       FIXED RENT
     ------             ---------                -----------       -----------

     01-12        $  19.20, Full-Service          $ 17,396.80       $ 208,761.60

     13-24        $  19.70, Full Service          $ 17,949.84       $ 214,198.08

     25-36        $  20.20, Full Service          $ 18,302.88       $ 219,634.56


          (f)  "Security Deposit": $ 34,793.60.
                ----------------

          (g)  "Estimated Occupancy Date": September 1, 1998.
                ------------------------

          (h)  "Tenant's Allocated Share": 9.50%;
                ------------------------
                Base Year Expense # 1999.
<PAGE>

          (i)  "Rentable Area":  Premises 10,874 ft.
                -------------
                                 Building 80,521 ft.

          (j)  "Permitted Uses": Tenant's use of the Premises shall be limited
                --------------
to general office use and storage incidental thereto. Tenant's rights to use the
Premises shall be subject to all applicable laws and governmental rules and
regulations and to all reasonable requirements of the insurers of the Building.

          (k)  "Broker" Colliars, Lanard and Axilbund
                ------

          (l)  "Notice Address/Contact"
                ----------------------

          Tenant:           Two Greenwood Square
                            Suite 275
                            Bensalem, Pennsylvania 19020
                            Attn: Aaron R. Brown
                            Phone: (610) 660-0100
                            FAX:   (610) 660-0334

          with a copy to:
                            Kaufman, Coren, Ress & Weidman, P.C.
                            1525 Locust Street, 17/th/ floor
                            Philadelphia, Pennsylvania 19103
                            Attn:  Steve Coren
                            Phone: (215) 735-8700

          Landlord:         BRANDYWINE OPERATING PARTNERSHIP, L.P.
                            Two Greenwood Square
                            3331 Street Road, Suite 300
                            Bensalem, PA 19020
                            Attn:  H. Jeffrey DeVuono
                                   Vice President -- Operations
                            Phone: (215) 245-0229
                            Fax:   (215) 245-4592

          with a copy to:
                            Brandywine Realty Trust
                            16 Campus Blvd.
                            Suite 150
                            Newtown Square, Pennsylvania 19073
                            Attn: Brad A. Molotsky
                                  General Counsel

                                      -2-
<PAGE>

          (m)  "Tenant's Standard Industrial Classification
                -------------------------------------------
               Number": __________
               ------

          (n)  "Additional Rent": All sums of money or charges required to be
                ---------------
               paid by Tenant under this Lease other than Fixed Rent, whether
               or not such sums or charges are designated as "Additional Rent".

          (o)  "Rent": All Annual Fixed Rent, monthly installments of Annual
                ----
               Fixed Rent, Fixed Rent and Additional Rent payable by Tenant to
               Landlord under this Lease.

     2.   PREMISES. Landlord does hereby lease, demise and let unto Tenant and
          --------
Tenant does hereby hire and lease from Landlord the Premises for the Term, upon
the provisions, conditions and limitations set forth herein.

     3.   TERM.
          ----

          (a)  The Term of this Lease shall commence (the "Commencement Date")
the date which is the earlier of (I) when Tenant, with Landlord's prior consent,
assumes possession of the Premises and commence business operations therein or
any part thereof, or (II) upon substantial completion of the Improvements
required to be made by Landlord, if any. The Premises shall be deemed
substantially completed when the improvements called for by Article 4 have been
completed to the extent that the Premises may be occupied by Tenant for its
Permitted Uses, subject only to completion of minor finishing, adjustment of
equipment, and other minor construction aspects, and Landlord has procured a
temporary certificate of occupancy permitting the occupancy the Premises.
Landlord shall endeavor to have the Premises substantially completed on or
before September 1, 1998.

          (b)  Upon notification by Landlord, Landlord and Tenant shall schedule
a pre-occupancy inspection of the Premises at which time a punch-list of
outstanding items, if any, shall be completed within a reasonable time
thereafter by Landlord for substantial conformance to the construction plans and
a letter of acceptance of the Premises shall be executed by both parties. The
Term shall expire on August 31, 2001. The Commencement Date shall be confirmed
by Landlord and Tenant by the execution of a Confirmation of Lease Term in the
form attached hereto as Exhibit "B". If Tenant fails to execute or object to the
                        -----------
Confirmation of Lease Term within ten (10) business days of its delivery,
Landlord's determination of such dates shall be deemed accepted.

          (c)  In the event that the Premises are not ready for Tenant's
occupancy at the time herein fixed for the beginning of the Term of this Lease,
because of any alterations or construction now or hereafter being carried on
either to the Premises or the Building (unless such alterations are being done
by Tenant or Tenant's contractor, in which case there shall be no suspension or
proration of rental or other sums), or because of any restrictions, limitations
or delays caused by government regulations or governmental agencies, this Lease
and the Term hereof shall not be affected thereby, nor shall Tenant be entitled
to make any claim for or receive any damages whatsoever from Landlord, and the
term hereof

                                      -3-
<PAGE>

shall nevertheless end on the date herein originally fixed, but no rent or other
sums herein provided to be paid by Tenant shall become due until the Premises
are substantially completed and deemed by Landlord to be ready for Tenant's
occupancy, and until that time, the rent and other sums due hereunder shall be
suspended.

          (d)  In the event Landlord is not able to deliver occupancy of the
Premises to Tenant by the Estimated Occupancy Date, Landlord shall make
available to Tenant storage space in the Building for storage of Tenant's
personal property until the Premises are available for Tenant's occupancy.
Tenant shall obtain such insurance on Tenant's personal property as Tenant may
desire and Landlord shall have no responsibility with respect to the condition
of, or any damage to, Tenant's personal property, including as a result of the
placement into, storage in or movement from the storage space provided by
Landlord under this Article 3(d). - think about whether space is available; if
this option is used, Tenant must be required to obtain insurance per Section 15.

     4.   CONSTRUCTION BY LANDLORD.
          ------------------------

          (a)  Landlord shall construct and do such other work (collectively,
the "Landlord's Work") in substantial conformity with the plans and outline
specifications of the plan which have been initialed by the parties, and which
are herein incorporated by reference Exhibit "A". If any material revision or
supplement to Landlord's Work is deemed necessary by Landlord, those revisions
and supplements shall be submitted to Tenant for approval, which approval shall
not be unreasonably withheld or delayed. If any change, revision or supplement
to the scope of the Landlord's Work is requested by Tenant or if Tenant fails to
provide information or cooperation required by Landlord in connection with
Landlord's Work within the time periods required (each, a "Tenant's Delay") then
such occurrence shall not change the Commencement Date of the Term and shall not
alter Tenant's obligations under this Lease so long as Landlord advises Tenant
in writing of such Tenant's Delay on or before five (5) business days from the
date of the occurrence of the event giving rise to the Tenant's Delay. The Term
shall commence on the date the Premises would have been delivered to Tenant but
for Tenant's Delay. Tenant shall be solely responsible for all reasonably
documented and invoiced expenses which increase the costs incurred in connection
with a Tenant requested change in the scope of the Landlord Work (including the
finishes set forth therein).

          (b)  Landlord shall endeavor to have the Landlord's Work be
substantially completed by the Estimated Occupancy Date; provided, however, that
the Estimated Occupancy Date shall be extended for that additional time equal to
the aggregate time lost by Landlord due to strikes or other labor disputes not
caused by Landlord, Tenant's Delay, intervening additional governmental
restrictions, scarcity of labor or materials, war or other emergency, accidents,
floods, fire or other casualties, atypical adverse weather conditions, or any
cause which is beyond the reasonable control of Landlord.

                                      -4-
<PAGE>

     5.   FIXED RENT: SECURITY DEPOSIT.
          ----------------------------

          (a)  Tenant shall pay to Landlord without notice or demand, and
without set-off, the annual Fixed Rent payable in the monthly installments of
Fixed Rent as set forth in Article 1(e), in advance on the first day of each
calendar month during the Term by wire transfer of immediately available funds
to the following account: First Union National Bank; ABA #031000503; account
#2030000359075; such transfer to be confirmed to Brandywine Realty Services
Corporation's accounting department (610-325-5622 -- fax) by written facsimile
with the applicable ABA routing number. Notwithstanding the immediately
preceding sentence, the first month's installment and the security deposit shall
be paid upon the execution of this Lease by Tenant. Otherwise, Fixed Rent shall
not commence nor be due and owing until the Commencement Date.

          (b)  In the event any Fixed Rent or Additional Rent, charge, fee or
other amount due from Tenant under the terms of this Lease are not paid to
Landlord within five (5) days of the date due and occurres more then two (2)
times in any given twelve month period, tenant shall also pay as Additional Rent
a service and handling charge equal to five (5%) percent of the total payment
then due. This provision shall not prevent Landlord from exercising any other
remedy herein provided or otherwise available at law or in equity in the event
of any default by Tenant.

          (c)  Tenant shall be required to pay a security deposit of $34,793.60
under this Lease (the "Collateral"), as security for the prompt, full and
faithful performance by Tenant of each and every provision of this Lease and of
all obligations of Tenant hereunder. No interest shall be paid to Tenant on the
Collateral, and Landlord shall have the right to commingle the Collateral with
Landlord's other funds. If Tenant fails to perform any of its obligations
hereunder, Landlord may use, apply or retain the whole or any part of the
Collateral for the payment of (i) any rent or other sums of money which Tenant
may not have paid when due, (ii) any sum expended by Landlord on Tenant's behalf
in accordance with the provisions of this Lease, and/or (iii) any sum which
Landlord may expend or be required to expend by reason of Tenant's default,
including, without limitation, any damage or deficiency in or from the reletting
of the Premises as provided in this Lease. The use, application or retention of
the Collateral, or any portion thereof, by Landlord shall not prevent Landlord
from exercising any other right or remedy provided by this Lease or by law (it
being intended that Landlord shall not first be required to proceed against the
Collateral) and shall not operate as a limitation on any recovery to which
Landlord may otherwise be entitled. If any portion of the Collateral is used,
applied or retained by Landlord for the purposes set forth above, Tenant agrees,
within ten days after the written demand therefor is made by Landlord, to
deposit cash with the Landlord in an amount sufficient to restore the Collateral
to its original amount.

          If Tenant shall fully and faithfully comply with all of the provisions
of this Lease, the Collateral, or any balance thereof, shall be returned to
Tenant without interest after the expiration of the Term or upon any later date
after which Tenant has vacated the Premises. In the absence of evidence
satisfactory to Landlord of any permitted assignment of the right to receive the
Collateral, or of the remaining balance thereof, Landlord may return the same to
the original Tenant, regardless of one or

                                      -5-
<PAGE>

more assignments of Tenant's interest in this Lease or the Collateral. In such
event, upon the return of the Collateral, or the remaining balance thereof to
the original Tenant, Landlord shall be completely relieved of liability under
this Paragraph or otherwise with respect to the Collateral.

          The Collateral shall not be mortgaged, assigned or encumbered in any
manner whatsoever by Tenant without the prior written consent of Landlord.

     6.   ADDITIONAL RENT.
          ---------------

          (a)  Commencing January 1, 2000, and in each calendar year thereafter
during the Term (as same may be extended), Tenant shall pay to Landlord, as
additional rent, within thirty (30) days after Landlord certifies to Tenant the
amount thereof, the following charges ("Recognized Expenses"), without deduction
or set off, such charges to be based upon Tenant's Allocated Share of such
charges in excess of the 1999 Base Year, as stated in Article 1(h) herein

               (1)  Insurance Premiums. All premiums paid or payable by Landlord
                    ------------------
for insurance with respect to the Project as follows:

                    (a)  Fire and extended coverage insurance (including
demolition and debris removal);

                    (b)  Insurance against Landlord's rental loss or abatement
(but not including business interruption coverage on behalf of Tenant), from
damage or destruction from fire or other casualty;

                    (c)  Landlord's comprehensive liability insurance (including
bodily injury and property damage) and boiler insurance; and

                    (d)  Such other insurance as Landlord or any reputable
mortgage lending institution holding a mortgage on the Premises may require.

If the coverage period of any of such insurance obtained by Landlord commences
before or extends beyond the Term, the premium therefore shall be prorated to
the Term. If any such insurance is provided by blanket coverage, the part of the
premium allocated to the Project shall be equitably determined by Landlord but
shall not exceed the amount of premium due if insurance was provided by a policy
only insuring the Project. Should Tenant's occupancy or use of the Premises at
any time change and thereby cause an increase in such insurance premiums on the
Premises, Building and/or Project, Tenant shall pay to Landlord the entire
amount of such reasonably documented increase.

                                      -6-
<PAGE>

          (2)  Operating Expenses. All costs and expenses related to the Project
               ------------------
incurred and paid (not to exceed 100% of all such costs) by Landlord during the
Term, including, but not limited to:

               (a)  All costs and expenses related to the operation of the
Building and Project, including, but not limited to, lighting, cleaning the
building exterior and common areas of the building interior, trash removal and
recycling repairs and maintenance of fire suppression and alarm systems,
removing snow, ice and debris and maintaining all landscape areas, (including
replacing and replanting flowers, shrubbery and trees), maintaining and
repairing all other exterior improvements on the Project, all repairs and
compliance costs necessitated by laws enacted or which become effective after
the date hereof (including, without limitation, any additional regulations or
requirements enacted after the date hereof regarding the American With
Disabilities Act (as such applies to the Project or common areas but not to any
individual tenant's space), storm water runoff and roof, if applicable) required
of Landlord under applicable laws, rules and regulations and policing and
regulating traffic to and from the Project. Landlord's obligation to provide
snow removal services shall be limited to the parking areas and the sidewalk
entrances.

               (b)  All costs and expenses incurred by Landlord for ordinary
compliance type environmental testing, sampling or monitoring required by
statute, regulation or order of governmental authority, necessary except any
costs or expenses incurred in conjunction with the spilling or depositing of any
hazardous substance for which any person or other tenant is legally liable.

               (c)  Any other non-capital expense or charge which would be
considered an expense of maintaining, operating or repairing the Project under
generally accepted accounting principles, including the cost of all utilities in
the common areas of the Property.

               (d)  Management fee not to exceed five (5%) percent of Fixed Rent
which is applicable to the overall operation of the Project. It is expressly
understood that legal fees incurred in an action against an individual tenant
shall not be deemed includable as an operating expense pursuant to this
      ---
provision.

               (e)  Capital expenditures shall be included as operating expenses
solely to the extent of the amortized costs of same over the useful life of the
------
improvement in accordance with generally accepted accounting principles.

               (f)  All charges for electricity, such charges to be based at
rates from the service provider, without markup. Landlord shall not be liable
for any interruption or delay in electric or any other utility service for any
reason unless caused by the gross negligence or willful misconduct of landlord
or its agents.

                                      -7-
<PAGE>

     Notwithstanding the foregoing, the term "Recognized Expenses" shall not
                                                                         ---
include any of the following:

          (a)  Repairs or other work occasioned by fire, windstorm or other
insured casualty plus and "deductibles" or by the exercise of the right of
eminent domain;

          (b)  Leasing commissions, accountants', consultants', auditors or
attorneys' fees, costs and disbursements and other expenses incurred in
connection with negotiations or disputes with other tenants or prospective
tenants or other occupants, or associated with the enforcement of any other
leases or the defense of Landlord's title to or interest in the real property or
any part thereof;

          (c)  Costs incurred by Landlord in connection with construction of the
Building and related facilities, the correction of defects in construction of
the Building or the discharge of Landlord's Work;

          (d)  Costs (including permit, licenses and inspection fees) incurred
in renovating or otherwise improving or decorating, painting, or redecorating
the Building or space for other tenants or other occupants or vacant space;

          (e)  Costs of any items or services sold or provided to tenants
(including Tenant) for which Landlord is reimbursed by such tenants, or which
are not generally provided to all tenants of the Building;

          (f)  Depreciation and amortization;

          (g)  Costs incurred due to a breach by Landlord or any other tenant
of the terms and conditions of any lease;

          (h)  Overhead and profit increment paid to subsidiaries or affiliates
of Landlord for management or other services on or to the Building or for
supplies or other materials, to the extent that the costs of such services,
supplies or materials exceed the reasonable costs that would have been paid had
the services, supplies or materials been provided by unaffiliated parties on a
reasonable basis;

          (i)  Interest on debt or amortization payments on any mortgage or
deeds of trust or any other borrowings and any ground rent;

          (j)  Ground rents or rentals payable by Landlord pursuant to any
over-lease;

                                      -8-
<PAGE>

          (k)  Any compensation paid to clerks, attendants or other persons in
commercial concessions operated by Landlord;

          (1)  All items and services for which Tenant reimburses Landlord or
pays third persons or which Landlord provides selectively to one or more tenants
or occupants of the building (other than Tenant) without reimbursement;

          (m)  Costs incurred in managing or operating any "pay for" parking
facilities within the Project;

          (n)  Expenses resulting from the gross negligence or wilful misconduct
of Landlord;

          (o)  Any fines or fees for Landlord's failure to comply with
governmental, quasi-governmental, or regulatory agencies' rules and regulations;
and

          (p)  Legal, accounting and other expenses related to Landlord's
financing, re-financing, mortgaging or selling the Building or the Project.

     (b)  Taxes. Taxes shall be defined as all taxes, assessments and other
          -----
governmental charges ("Taxes"), including special assessments for public
improvements which are levied or assessed against the Project during the Term
or, if levied or assessed prior to the Term, which properly are allocable to the
Term, and real estate tax appeal expenditures incurred by Landlord to the extent
of any reduction resulting thereby.

          Nothing herein contained shall be construed to include as Taxes: (A)
any inheritance, estate, succession, transfer, gift, franchise, corporation, net
income or profit tax or capital levy that is or may be imposed upon Landlord or
(B) any Taxes resulting from a transfer of the Building or the Project or (C)
any increase in Taxes due to capital improvements other than tenant improvements
in the Building; provided, however, that if at any time during the Term the
method of taxation prevailing at the commencement of the Term shall be altered
so that in lieu of or as a substitute for the whole or any part of the taxes now
levied, assessed or imposed on real estate as such there shall be levied,
assessed or imposed (i) a tax on the rents received from such real estate, or
(ii) a license fee measured by the rents receivable by Landlord from the
Premises or any portion thereof, or (iii) a tax or license fee imposed upon
Premises or any portion thereof, then the same shall be included in the
computation of Taxes hereunder.

     (c)  Commencing January 1, 2000, Tenant shall pay, in monthly installments
in advance, on account of Tenant's Allocated Share of Recognized Expenses and
Taxes, the estimated amount of the increase of such Recognized Expenses and
Taxes for such year in excess of the 1999 Base Year as determined by Landlord in
its reasonable discretion and as set forth in a notice, such notice to include
the basis for such calculation, to be provided to Tenant prior to such date.
Prior to the end of that

                                      -9-
<PAGE>

year and thereafter for each successive calendar year (each, a "Lease Year"), or
part thereof, Landlord shall send to Tenant a statement of projected increases
in Recognized Expenses and Taxes in excess of 1998 Base Year and shall indicate
what Tenant's projected share of Recognized Expenses and Taxes shall be. Said
amount shall be paid in equal monthly installments in advance by Tenant as
Additional Rent commencing January 1 of the applicable Lease Year.

               Tenant shall have the right, at its sole cost and expense, to
audit or have its appointed accountant audit Landlord's records related to
Recognized Expenses and Taxes provided that any such audit may not occur more
frequently than once each calendar year nor apply to any year prior to the then
current calendar year and, in each event, the year 1999. In the event Tenant's
audit discloses any discrepancy, Landlord and Tenant shall use their best
efforts to resolve the dispute and make an appropriate adjustment, failing
which, they shall submit any such dispute to arbitration pursuant to the rules
and under the jurisdiction of the American Arbitration Association in
Philadelphia, Pennsylvania. The decision rendered in such arbitration shall be
final, binding and non-appealable. The expenses of arbitration, other than
individual legal and accounting expenses which shall be the respective parties'
responsibility, shall be divided equally between the parties. In the event, by
agreement or as a result of an arbitration decision, it is determined that the
actual Recognized Expenses and Taxes exceeded those claimed by the Landlord by
more than ten percent (10%) the actual, reasonable hourly costs to Tenant of
Tenant's audit (including legal and accounting costs) shall be reimbursed by
Landlord.

          (d)  If during the course of any Lease Year, Landlord shall have
reason to believe that the Recognized Expenses and Taxes shall be different than
that upon which the aforesaid projections were originally based, then Landlord
shall be entitled to adjust the amount by reallocating the remaining payments
for such year, for the months of the Lease Year which remain for the revised
projections, and to advise Tenant of an adjustment in future monthly amounts to
the end result that the Recognized Expenses and Taxes shall be collected on a
reasonably current basis each Lease Year.

         (e)   Within four (4) months following the end of each Lease Year or as
soon thereafter as administratively available, Landlord shall send to Tenant a
statement of actual expenses incurred for Recognized Expenses and Taxes for the
prior Lease Year showing the Allocated Share due from Tenant. Landlord shall use
its reasonable efforts to provide Tenant with the aforesaid statements on or
before April 30 of each lease year; provided, however, if Landlord is unable to
provide such statements by April 30, Landlord shall not have been deemed to
waive its right to collect any such amounts as Additional Rent. If Landlord is
unable to provide final statements on or before April 30 of each Lease year,
Landlord shall provide Tenant with its unaudited internal estimates of such
costs by April 30, with the caveat that the final statements may deviate from
the estimate provided. In the event the amount prepaid by Tenant exceeds the
amount that was actually due then Landlord shall issue a credit to Tenant in an
amount equal to the over charge, which credit Tenant may apply to future
payments on account of Recognized Expenses and Taxes until Tenant has been fully
credited with the over charge. If the credit due to Tenant is more than the
aggregate total of future rental payments, Landlord shall pay to Tenant the
difference between the credit in such aggregate total. In the event Landlord has
undercharged Tenant then Landlord shall send Tenant an invoice with the
additional amount due, which amount shall be paid in full by Tenant within
twenty (20) days of receipt.

                                     -10-
<PAGE>

          (f)  Each of the Recognized Expense and Tax amounts, whether requiring
lump sum payment or constituting projected monthly amounts added to the Fixed
Rent, shall for all purposes be treated and considered as Additional Rent and
the failure of Tenant to pay the same as and when due in advance and without
demand shall have the same effect as failure to pay any installment of the Fixed
Rent and shall afford Landlord all the remedies in the Lease therefor as well as
at law or in equity.

          (g)  If this Lease terminates other than at the end of a calendar
year, Landlord's annual estimate of Recognized Expenses and Taxes shall be
accepted by the parties as the actual Recognized Expenses and Taxes for the year
the Lease ends unless Landlord provides Tenant with actual statements in
accordance with subsection 6(e) above.

     7.   SIGNS; USE OF PREMISES AND COMMON AREAS.
          ---------------------------------------

          (a)  As part of Tenant fit-out cost, Landlord shall provide Tenant
with standard identification signage on all Building directories and at the
entrance to the Premises. No other signs shall be placed, erected or maintained
by Tenant at any place upon the Premises, Building or Project.

          (b)  Tenant may use and occupy the Premises only for the express and
limited purposes stated in Article 1(j) above; and the Premises shall not be
used or occupied, in whole or in part, for any other purpose without the prior
written consent of Landlord; provided that Tenant's right to so use and occupy
the Premises shall remain expressly subject to the provisions of "Governmental
Regulations", Article 28 herein. No machinery or equipment shall be permitted
that shall cause vibration, noise or disturbance beyond the Premises. Tenant,
without Landlord's consent or direction, shall not "vacate" the Premises at any
time during the Term, nor permit the Premises to remain unoccupied. "Vacate"
shall be defined as the removal of substantially all of the firm's client files
or all of its furniture and equipment and personal property from the Premises.

          (c)  Tenant shall not commit or suffer any waste upon the Premises,
Building or Project or any nuisance, or any other act or thing which may disturb
the quiet enjoyment of any other tenant in the Building or Project.

          (d)  Tenant shall have the right, non-exclusive and in common with
others, to use the exterior paved driveways and walkways of the Building for
vehicular and pedestrian access to the Building. Tenant shall also have the
right, in common with other tenants of the Building and Landlord, to use the
designated parking areas of the Project and for the parking of automobiles of
Tenant and its employees and business visitors, incident to Tenant's permitted
use of the Premises; provided that Landlord shall have the right to restrict or
limit Tenant's utilization of the parking areas in the event the same become
overburdened and in such case to equitably allocate on proportionate basis or
assign parking spaces among Tenant and the other tenants of the Building.
Landlord shall have the right to establish reasonable regulations, applicable to
all tenants, governing the use of or access to any interior or exterior common
areas; and such regulations, when communicated by written notification from
Landlord to Tenant, shall be deemed incorporated by reference hereinafter and
part of this Lease.

                                     -11-
<PAGE>

     8.   ENVIRONMENTAL MATTERS.
          ---------------------

          (a)  Hazardous Substances.
               --------------------

               (i)  Tenant shall not, except as provided in subparagraph (ii)
below, bring or otherwise cause to be brought or permit any of its agents,
employees, contractors or invitees to bring in, on or about any part of the
Premises, Building or Project, any hazardous substance or hazardous waste in
violation of law, as such terms are or may be defined in (x) the Comprehensive
Environmental Response, Compensation and Liability Act, 42 U.S.C. 9601 et seq.,
                                                                       -- ---
as the same may from time to time be amended, and the regulations promulgated
pursuant thereto ("CERCLA"); the United States Department of Transportation
Hazardous Materials Table (49 CFR 172.102); by the Environmental Protection
Agency as hazardous substances (40 CFR Part 302); the Clean Air Act; and the
Clean Water Act, and all amendments, modifications or supplements thereto;
and/or (y) any other rule, regulation, ordinance, statute or requirements of any
governmental or administrative agency regarding the environment (collectively,
(x) and (y) shall be referred to as an applicable "Environmental Law").

               (ii) Tenant may bring to and use at the Premises, hazardous
substances, supplies or other items, incidental to its normal business
operations under the SIC Code referenced in paragraph 1(n) above in de minimis
quantities in accordance with all laws. Tenant shall store and handle such
substances in strict accordance with all environmental laws.

          (b)  SIC Numbers.
               -----------

               (i)  Tenant represents and warrants that Tenant's SIC (Standard
Industrial Classification) number as designated in the Standard Classification
Manual prepared by the Office of Management and Budget, and as set forth in
Article 1(m) hereof, is correct. Tenant represents that the specific activities
intended to be carried on in the Premises are in accordance with Article 1(k)
and Tenant covenants and agrees that it will not do or suffer anything which
will cause its SIC number (or that of any assignee or subtenant) to fall within
any of the following "major group" classifications of SIC numbers during the
Term (and any exercised renewal term) hereof: 22 through 39 inclusive, 46
through 49 inclusive, 51 and 76 (together the "Covered Numbers"). Tenant further
covenants and agrees to notify Landlord at least thirty (30) days prior to any
change of facts which would result in the change of Tenant's SIC number from its
present number to any of the Covered Numbers. Upon such notice, Landlord shall
have the right, at its option, to terminate this Lease within thirty (30) days
of receipt of such notice by notifying Tenant in writing.

               (ii) Tenant shall not engage in operations at the Premises which
involve the generation, manufacture, refining, transportation, treatment,
storage, handling or disposal of "hazardous substances" or "hazardous waste" as
such terms are defined under any applicable Environmental Law. Tenant further
covenants that it will not cause or permit to exist any "discharge" (as such
term is defined under Applicable Environmental Laws) on or about the Premises.

                                     -12-
<PAGE>

               (iii) Tenant shall, at its expense, comply with all requirements
of Applicable Environmental Laws pertaining thereto.

               (iv)  In addition, upon written request of Landlord, Tenant shall
cooperate with Landlord in obtaining Applicable Environmental Laws approval of
any transfer of the Building of which the Premises form a part. Specifically in
that regard, Tenant agrees that it shall (1) execute and deliver all affidavits,
reports, responses to questions, applications or other filings required by
Landlord and related to Tenant's activities at the Premises, (2) allow
inspections and testing of the Premises, and (3) as respects the Premises
occupied by Tenant, perform any requirement reasonably requested by Landlord
necessary for the receipt of Applicable Environmental Laws approval, provided
the foregoing shall be at no out-of-pocket cost or expense to Tenant except for
clean-up and remediation costs arising from Tenant's activities at the Premises.

          (c)  Additional Terms.
               ----------------

               (i)   In the event of Tenant's failure to comply in full with
this Article, Landlord may, after written notice to Tenant and Tenant's failure
to cure within 30 days of its receipt of such notice, at Landlord's option,
perform any and all of Tenant's obligations as aforesaid and all costs and
expenses incurred by Landlord in the exercise of this right shall be deemed to
be Additional Rent payable on demand and with interest at the Default Rate until
payment at the rate provided in this Lease.

               (ii)  The parties acknowledge and agree that Tenant shall not be
held responsible for any environmental issue at the Premises unless such issue
was caused by an action or omission of Tenant or its agents, employees,
consultants or invitees.

               (iii) This Article 9 shall survive the expiration or sooner
termination of this Lease.

     9.   TENANT'S ALTERATIONS. Tenant will not cut or drill into or secure any
          --------------------
fixture, apparatus or equipment or make alterations, improvements or physical
additions (collectively, "Alterations") of any kind to any part of the Premise
without first obtaining the written consent of Landlord not to be unreasonably
withheld. Alterations shall, at Landlord's option, be done by Landlord at
Tenant's sole cost and expense. Landlord's consent shall not be required for the
installation of any office equipment or fixtures including internal partitions
which do not require disturbance of any structural elements or systems (other
than attachment thereto) within the Building. If Landlord approves Tenant's
Alterations and agrees to permit Tenant's contractors to do the work, Tenant,
prior to the commencement of labor or supply of any materials, must furnish to
Landlord (i) a duplicate or original policy or certificates of insurance
evidencing (a) general public liability insurance for personal injury and
property damage in the minimum amount of $1,000,000.00 combined single limit,
(b) statutory workman's compensation insurance, and (c) employer's liability
insurance from each contractor to be employed (all such policies shall be non-
cancelable without thirty (30) days prior written notice to Landlord and shall
be in amounts and with companies satisfactory to Landlord); (ii) construction
documents prepared and sealed by a registered Pennsylvania architect if such
alteration is in excess of $15,000; and (iii) all applicable building permits
required by law. Any consent by Landlord permitting

                                     -13-
<PAGE>

Tenant to do any or cause any work to be done in or about the Premises shall be
and hereby is conditioned upon Tenant's work being performed by workmen and
mechanics working in harmony and not interfering with labor employed by
Landlord, Landlord's mechanics or their contractors or by any other tenant or
their contractors. If at any time any of the workmen or mechanics performing any
of Tenant's work shall be unable to work in harmony or shall interfere with any
labor employed by Landlord, other tenants or their respective mechanics and
contractors, then the permission granted by Landlord to Tenant permitting Tenant
to do or cause any work to be done in or about the Premises, may be withdrawn by
Landlord upon forty-eight (48) hours written notice to Tenant.

     All Alterations (whether temporary or permanent in character) made in or
upon the Premises (other than the Landlord Work which will remain on the
Premises), either by Landlord or Tenant, shall be Landlord's property upon
installation and shall remain on the Premises without compensation to Tenant
unless Landlord shall, upon granting its approval for such Alterations, have
given written notice to Tenant to remove same at the expiration of the Lease, in
which event Tenant shall promptly remove such Alterations and restore the
Premises to good order and condition. Should Tenant fail to do so, Landlord may
do so, collecting at Landlord's option the cost and expense thereof from Tenant
as Additional Rent. All furniture, movable trade fixtures and equipment
installed by Tenant may be removed by Tenant at the termination of this Lease,
or if not so removed shall, at the option of Landlord, become the property of
Landlord. All such installations, removals and restoration shall be accomplished
in a good and workmanlike manner so as not to damage the Premises or Building
and in such manner so as not to disturb other tenants in the Building. If Tenant
fails to remove any items required to be removed pursuant to this Article,
Landlord may do so and the reasonable costs and expenses thereof shall be deemed
Additional Rent hereunder and shall be reimbursed by Tenant to Landlord within
fifteen (15) business days of Tenant's receipt of an invoice therefore from
Landlord.

     10.  CONSTRUCTION LIENS.
          ------------------

          (a)  Tenant will not voluntarily suffer or permit any contractor's,
subcontractor's or supplier's lien (a "Construction Lien") to be filed against
the Premises or any part thereof by reason of work, labor services or materials
supplied or claimed to have been supplied to Tenant; and if any Construction
Lien shall at any time be filed against the Premises or any part thereof,
Tenant, within thirty (30) days after notice of the filing thereof, shall cause
it to be discharged of record by payment, deposit, bond, order of a court or
competent jurisdiction or otherwise. If Tenant shall fail to cause such
Construction Lien to be discharged within the period aforesaid, then in addition
to any other right or remedy, Landlord may, but shall not be obligated to,
discharge it either by paying the amount claimed to be due or by procuring the
discharge of such lien by deposit or by bonding proceedings. Any amount so paid
by Landlord, plus all of Landlord's costs and expenses associated therewith
(including, without limitation, reasonable legal fees), shall constitute
Additional Rent payable by Tenant under this Lease and shall be paid by Tenant
to Landlord on demand with interest from the date of advance by Landlord at the
Default Rate.

          (b)  Nothing in this Lease, or in any consent to the making of
alterations or improvements contained shall be deemed or construed in any way as
constituting authorization by

                                     -14-
<PAGE>

Landlord for the making of any alterations or additions by Tenant within the
meaning of 49 P.S. Sections 1101-1902, as amended or under the Contractor and
Subcontractor Payment Act or any amendment thereof, or constituting a request by
Landlord, express or implied, to any contractor, subcontractor or supplier for
the performance of any labor or the furnishing of any materials for the use or
benefit or Landlord.

     11.  ASSIGNMENT AND SUBLETTING.
          -------------------------

          (a)  Subject to the remaining subsections of Section 12, except as
expressly permitted pursuant to this section, Tenant shall not, without the
prior written consent of Landlord, such consent not to be unreasonably withheld,
assign or hypothecate this Lease or any interest herein or sublet the Premises
or any part thereof. Any of the foregoing acts without such consent shall be
void and shall, at the option of Landlord, terminate this Lease. Subject to
subsection 12(g) below, this Lease shall not, nor shall any interest herein, be
assignable as to the interest of Tenant by operation of law without the written
consent of Landlord.

          (b)  If at any time or from time to time during the term of this Lease
Tenant desires to assign all or any part of the Premises, Tenant shall give
notice to Landlord of such intent. Landlord shall have the option, exercisable
by notice given to Tenant within twenty (20) days after receipt of Tenant's
notice, of reacquiring the portion of the Premises proposed to be assigned and
terminating the Lease with respect thereto.

          (c)  Any sums or other economic consideration received by Tenant as a
result of any subletting or assignment (except rental or other payments received
which are attributable to the amortization of the cost of leasehold improvements
made to the sublet or assigned portion of the premises by Tenant for subtenant
or assignee, and other reasonable expenses incident to the subletting or
assignment, including standard leasing commissions) whether denominated rentals
under the sublease or otherwise, which exceed, in the aggregate, the total sums
which Tenant is obligated to pay Landlord under this Lease (prorated to reflect
obligations allocable to that portion of the premises subject to such sublease
or assignment) shall be divided evenly between Landlord and Tenant, with
Landlord's portion being payable to Landlord as Additional Rental under this
Lease without affecting or reducing any other obligation of Tenant hereunder.

          (d)  Regardless of Landlord's consent, no subletting or assignment
shall release Tenant of Tenant's obligation or alter the primary liability of
Tenant to pay the Rent and to perform all other obligations to be performed by
Tenant hereunder. The acceptance of rental by Landlord from any other person
shall not be deemed to be a waiver by Landlord of any provision hereof. Consent
to one assignment or subletting shall not be deemed consent to any subsequent
assignment or subletting. In the event of default by any assignee of Tenant or
any successor of Tenant in the performance of any of the terms hereof, Landlord
may proceed directly against Tenant without the necessity of exhausting remedies
against such assignee or successor.

          (e)  In the event that (i) the Premises or any part thereof are sublet
and Tenant is in

                                     -15-
<PAGE>

default under this Lease, or (ii) this Lease is assigned by Tenant, then,
Landlord may collect Rent from the assignee or subtenant and apply the net
amount collected to the rent herein reserved; but no such collection shall be
deemed a waiver of the provisions of this Article 12 with respect to assignment
and subletting, or the acceptance of such assignee or subtenant as Tenant
hereunder, or a release of Tenant from further performance of the covenants
herein contained.

     12.  LANDLORD'S RIGHT OF ENTRY. Landlord and persons authorized by Landlord
          -------------------------
may enter the Premises at all reasonable times upon twenty-four (24) hours
notice (except in the case of an emergency in which case no prior notice is
necessary) for the purpose of inspections, repairs, alterations to adjoining
space, appraisals, or other reasonable purposes; including enforcement of
landlord's rights under this Lease. Landlord shall not be liable for
inconvenience to or disturbance of Tenant by reason of any such entry; provided,
however, that in the case of repairs or work, such shall be done, so far as
practicable, so as to not unreasonably interfere with Tenant's use of the
Premises. Landlord also shall have the right to enter the Premises at all
reasonable times after giving prior notice to Tenant, to exhibit the Premises to
any prospective purchaser, tenant and/or mortgagee.

     13.  REPAIRS AND MAINTENANCE.
          -----------------------

          (a)  Except as specifically otherwise provided in Paragraphs (b) and
(c) of this Article, Tenant, at its sole cost and expense and throughout the
Term of this Lease, shall keep and maintain the Premises in good order and
condition, free of accumulation of dirt and rubbish, and shall promptly make all
non-structural repairs necessary to keep and maintain such good order and
condition. Tenant shall have the option of replacing lights, ballasts, tubes,
ceiling tiles, outlets and similar equipment itself or it shall have the ability
to advise Landlord of Tenant's desire to have Landlord make such repairs. If
requested by Tenant, Landlord shall make such repairs to the Premises within a
reasonable time of notice to Landlord and shall charge Tenant for such services
at Landlord's standard rate (such rate to be competitive with the market rate
for such services). Tenant shall not use or permit the use of any portion of the
Premises for outdoor storage. When used in this Article 14, the term "repairs"
shall include replacements and renewals when necessary. All repairs made by
Tenant shall utilize materials and equipment which are at least equal in quality
and usefulness to those originally used in constructing the Building and the
Premises. Landlord shall maintain all HVAC systems serving the Building and the
Premises. Tenant's allocated share of Landlord's cost for HVAC service,
maintenance and repairs shall be included as a portion of Recognized Expenses.

          (b)  Landlord, throughout the Term of this Lease and at Landlord's
sole cost and expenses, shall make all necessary repairs to the footings and
foundations and the structural steel columns and girders forming a part of the
Premises and the HVAC, plumbing and electric systems serving the Premises.

          (c)  Landlord, throughout the Term of this Lease, shall make all
necessary repairs to the Building outside of the Premises and the common areas,
including the roof, walls, exterior portions of the Premises and the Building,
utility lines, equipment and other utility facilities in the Building,

                                     -16-
<PAGE>

which serve more than one tenant of the Building, and to any driveways,
sidewalks, curbs, loading, parking and landscaped areas, and other exterior
improvements for the Building; provided, however, that Landlord shall have no
responsibility to make any repairs unless and until Landlord receives written
notice of the need for such repair. Tenant shall pay its Allocated Share of the
cost of all repairs to be performed by Landlord pursuant to this Paragraph 14(c)
as Additional Rent as provided, and as limited by with respect to capital items,
in Article 6 hereof.

          (d)  Landlord shall keep and maintain all common areas appurtenant to
the Building and any sidewalks, parking areas, curbs and access ways adjoining
the Property in a clean and orderly condition, free of accumulation of dirt,
rubbish, snow and ice, and shall keep and maintain all landscaped areas in a
neat and orderly condition. Tenant shall pay its Allocated Share of the cost of
all work to be performed by Landlord pursuant to this Paragraph (d) as
Additional Rent as provided in Article 6 to hereof.

          (e)  Notwithstanding anything herein to the contrary, repairs to the
Premises, Building or Project and its appurtenant common areas made necessary by
a negligent or willful act or omission of Tenant or any employee, agent,
contractor, or invitee of Tenant shall be made at the sole cost and expense of
Tenant, except to the extent covered by Landlord's insurance.

          (f)  Landlord shall provide Tenant with janitorial services for the
Premises Monday through Friday of each week in accordance with the guidelines
set forth in Exhibit "D" attached hereto.
             -----------

     14.  INSURANCE; SUBROGATION RIGHTS.
          ----------------------------

          (a)  Tenant shall obtain and keep in force at all times during the
term hereof, at its own expense, comprehensive general liability insurance
including contractual liability and personal injury liability and all similar
coverage, with combined single limits of $1,000,000.00 on account of bodily
injury to or death of one or more persons as the result of any one accident or
disaster and $1,000,000.00 on account of damage to property, or in such other
amounts as Landlord may from time to time require. The policy limits set forth
herein shall be subject to periodic review, and Landlord reserves the right to
require that Tenant increase the liability coverage limits if, in the reasonable
opinion of Landlord, the coverage becomes inadequate and is less than commonly
maintained by tenants of similar buildings in the area making similar uses.

          (b)  Tenant shall, at its sole cost and expense, maintain in full
force and effect on all Tenant's trade fixtures, equipment and personal property
on the Premises, a policy of all risk property insurance covering the full
replacement value of such property. Tenant shall also provide and keep in force,
business interruption insurance in an amount equivalent to twelve (12) months'
Rent and Additional Rent which shall not contain a deductible greater than
seventy-two (72) hours.

          (c)  All insurance required hereunder shall not be subject to
cancellation without at least thirty (30) days prior notice to all insureds, and
shall name Landlord, Landlord's Agent and Tenant as insureds, as their interests
may appear, and, if requested by Landlord, shall also name as an additional

                                     -17-
<PAGE>

insured any mortgagee or holder of any mortgage which may be or become a lien
upon any part of the Premises. Prior to the commencement of the Term, Tenant
shall provide Landlord with certificates or copies of the policy or policies of
insurance above referred to, with evidence that the premiums have been paid in
full for the policy periods. Tenant shall also furnish to Landlord throughout
the term hereof replacement certificates or copies of renewal policies, together
with evidence of like paid premiums at least thirty (30) days prior to the
expiration dates of the then current policy or policies. All the insurance
required under this Lease shall be issued by insurance companies authorized to
do business in the Commonwealth of Pennsylvania with a financial rating of at
least an A+ as rated in the most recent edition of Best's Insurance Reports and
in business for the past five years. The limit of any such insurance shall not
limit the liability of Tenant hereunder. If Tenant fails to procure and maintain
such insurance, Landlord may, but shall not be required to, procure and maintain
the same, at Tenant's expense to be reimbursed by Tenant as Additional Rent
within ten (10) days of written demand. Any deductible under such insurance
policy in excess of One Thousand ($1,000) must be approved by Landlord in
writing prior to issuance of such policy. The policy limits set forth herein
shall be subject to periodic review, and Landlord reserves the right to require
that Tenant increase the liability coverage limits if, in the reasonable opinion
of Landlord, the coverage becomes inadequate and is less than commonly
maintained by tenants of similar buildings in the area making similar uses.

          (d)  Landlord shall obtain and maintain the following insurance during
the Term of this Lease: (i) replacement cost insurance (including damage for
theft, vandalism, malicious mischief, sprinkler leakage and flood) on the
Project, (ii) builder's risk insurance for the tenant improvements to be
constructed in the Project, and (iii) comprehensive liability insurance
(including bodily injury and property damage) covering Landlord's operations at
the Project in amounts reasonably required by the Landlord's lender.

          (e)  Each party hereto, and anyone claiming through or under them by
way of subrogation, waives and releases any cause of action it might have
against the other party and its employees, officers, partners, trustees and
agents, on account of any loss or damage that is insured against under any
insurance policy required to be obtained hereunder (to the extent that such loss
or damage is recoverable under such insurance policy) that covers the Project,
Building or Premises, Landlord's or Tenant's fixtures, personal property,
leasehold improvements or business and which names Landlord or Tenant, as the
case may be, as a party insured. Each party hereto agrees that it will cause its
insurance carrier to endorse all applicable policies waiving the carrier's right
of recovery under subrogation or otherwise against the other party. During any
period while such waiver of right of recovery is in effect, each party shall
look solely to the proceeds of such policies for compensation for loss, to the
extent such proceeds are paid under such policies.

     15.  INDEMNIFICATION. Tenant shall indemnify and hold harmless Landlord and
          ---------------
its employees and agents from and against any and all third-party claims,
actions, damages, liability and expense (including all expenses and liabilities
incurred in defense of any such claim or any action or proceeding brought
thereon) arising from (i) Tenant's improper use of the Premises, (ii) the
improper conduct of Tenant's business, (iii) any activity, work or things done,
permitted or suffered by Tenant in or about the Premises or elsewhere contrary
to the requirements of the Lease, (iv) any breach or default

                                     -18-
<PAGE>

in the performance of any obligation of Tenant's part to be performed under the
terms of this Lease, and (v) any negligence or willful act of Tenant or any of
Tenant's agents, contractors or employees, and in case Landlord shall be made a
party to any litigation commenced by or against Tenant, its agents, subtenants,
licensees, concessionaires, contractors, customers or employees, then Tenant
shall defend, indemnify and hold harmless Landlord and shall pay all costs,
expenses and reasonable attorney's fees incurred or paid by Landlord in
connection with such litigation, after notice to Tenant and Tenant's refusal to
defend such litigation, and upon notice from Landlord shall defend the same at
Tenant's expense by counsel satisfactory to Landlord. Tenant shall further
indemnify and hold harmless Landlord from and against any and all third-party
claims, actions, damages, liability and expense which may be imposed upon or
incurred by or asserted against Landlord by reason of(a) loss of life, personal
injury and/or damage to property occurring in or about, or arising out of, the
Premises, adjacent sidewalks and loading platforms or areas and common areas
appurtenant to the Building occasioned by reason of any act or omission of
Tenant, its agents, subtenants, licensees, concessionaires, contractors,
customers or employees and (b) any failure on the part of Tenant to keep,
observe and perform any of the terms, covenants, agreements, conditions,
limitations or Rules and Regulations contained in this Lease on Tenant's part to
be kept, observed and performed.

        16. QUIET ENJOYMENT. Provided Tenant has performed all of the terms and
            ---------------
conditions of this Lease, including the payment of Fixed Rent and Additional
Rent, to be performed by Tenant, Tenant shall peaceably and quietly hold and
enjoy the Premises for the Term, without hindrance from Landlord, or anyone
claiming by through or under Landlord under and subject to the terms and
conditions of this lease and of any mortgages now or hereafter affecting all of
or any portion of the Premises.

        17. FIRE DAMAGE.
            -----------
            (a)  Except as provided below, in case of damage to the Premises
by fire or other insured casualty, Landlord shall repair the damage. Such repair
work shall be commenced promptly following notice of the damage and completed
with due diligence, taking into account the time required for Landlord to effect
a settlement with and procure insurance proceeds from the insurer, except for
delays due to governmental regulation, scarcity of or inability to obtain labor
or materials, intervening acts of God or other causes beyond Landlord's
reasonable control.

            (b)  Notwithstanding the foregoing, if (i) the damage is of a
nature or extent that, in Landlord's reasonable judgment (to be communicated to
Tenant within sixty (60) days from the date of the casualty), the repair and
restoration work would require more than one hundred twenty (120) consecutive
days to complete after the casualty and, assuming normal work crews not engaged
in overtime, or (ii) if more than thirty (30%) percent of the total area of the
Building is extensively damaged, Landlord shall have the right to terminate this
Lease and all the unaccrued obligations of the parties hereto, by sending
written notice of such termination to the other within ten (10) days of Tenant's
receipt of the notice from Landlord described above. Such notice is to specify a
termination date no less than fifteen (15) days after its transmission;
provided, however, that in addition to the foregoing, in the event Tenant shall
have also vacated the Premises because the nature or extent of the damage
rendered

                                     -19-
<PAGE>

the Premises untenantable, Tenant may by notice in writing to Landlord within
five (5) days of receipt of Landlord's written notice elect to make the
termination of the Lease retroactive to the date of such vacation of the
Premises by Tenant. Notwithstanding the foregoing, in the event Tenant is
responsible for the aforesaid casualty, Tenant shall not have the right to
                                                     ---
terminate this Lease if Landlord is willing to rebuild and restore the Premises.

            (c)  If the insurance proceeds received by Landlord as dictated by
the terms and conditions of any financing then existing on the Building,
(excluding any rent insurance proceeds) would not be sufficient to pay for
repairing the damage or are required to be applied on account of any mortgage
which encumbers any part of the Premises or Building, or if the nature of loss
is not covered by Landlord's fire insurance coverage, Landlord may elect either
to (i) repair the damage as above provided notwithstanding such fact or (ii)
terminate this Lease by giving Tenant notice of Landlord's election within
thirty (30) days after Landlord's knowledge of the damage and of the
unavailability or insufficiency of insurance proceeds. If the election is to
terminate, Landlord shall give Tenant at least fifteen (15) days prior notice
specifying the termination date.

            (d)  In the event Landlord has not completed restoration of the
Premises within one hundred twenty (120) days from the date of casualty (subject
to delay due to weather conditions, shortages of labor or materials or other
reasons beyond Landlord's control which delay in any event will not exceed an
additional thirty (30) business days), Tenant may terminate this Lease by
written notice to Landlord within thirty (30) business days following the
expiration of such 120 day period (as extended for reasons beyond Landlord's
control as provided above) unless, within thirty (30) business days following
receipt of such notice, Landlord has completed such restoration and delivered
the Premises to Tenant for occupancy.

            (e)  In the event of damage or destruction to the Premises or any
part thereof, Tenant's obligation to pay Fixed Rent and Additional Rent shall be
equitably adjusted or abated. Not withstanding the foregoing, there shall be no
abatement in Rent or Additional Rent if Tenant caused or is responsible for the
casualty.

        18. SUBORDINATION: RIGHTS OF MORTGAGEE.
            ----------------------------------

            (a)  This Lease shall be subject and subordinate at all times to
the lien of any mortgages now or hereafter placed upon the Premises, Building
and/or Project and land of which they are a part without the necessity of any
further instrument or act on the part of Tenant to effectuate such
subordination. Tenant further agrees to execute and deliver upon demand such
further instrument or instruments evidencing such subordination of this Lease to
the lien of any such mortgage and such further instrument or instruments of
attornment as shall be desired by any mortgagee or proposed mortgagee or by any
other person. Notwithstanding the foregoing, any mortgagee may at any time
subordinate its mortgage to this Lease, without Tenant's consent, by notice in
writing to Tenant, and thereupon this Lease shall be deemed prior to such
mortgage without regard to their respective dates of execution and delivery and
in that event such mortgagee shall have the same rights with respect to this
Lease as though it had been executed prior to the execution and delivery of the
mortgage.

                                     -20-
<PAGE>

            (b)  In the event Landlord shall be or is alleged to be in default
of any of its obligations owing to Tenant under this Lease, Tenant agrees to
give to the holder of any mortgage (collectively the "Mortgagee") now or
hereafter placed upon the Premises, Building and/or Project, notice by
registered mail of any such default which Tenant shall have served upon
Landlord, provided that prior thereto Tenant has been notified in writing (by
way of Notice of Assignment of Rents and/or Leases or otherwise in writing to
Tenant) of the name and addresses of any such Mortgagee. Tenant shall not be
entitled to exercise any right or remedy as there may be because of any default
by Landlord without having given such notice to the Mortgagee; and Tenant
further agrees that if Landlord shall fail to cure such default: (i) the
Mortgagee shall have any additional time periods (measured from the later of the
date on which the default should have been cured by Landlord or the Mortgagee's
receipt of such notice from Tenant), within which to cure such default, provided
that if such default be such that the same could not be cured within such period
and is diligently pursuing the remedies necessary to effectuate the cure
(including but not limited to foreclosure proceedings if necessary to effectuate
the cure); and (ii) Tenant shall not exercise any right or remedy as there may
be arising because of Landlord's default, including but not limited to,
termination of this Lease as may be expressly provided for herein or available
to Tenant as a matter of law, if the Mortgagee either has cured the default
within such time periods, or as the case may be, has initiated the cure of same
within such period and is diligently pursuing the cure of same as aforesaid.

        19. CONDEMNATION.
            ------------

            (a) If more than twenty (20%) percent of the floor area of the
Premises is taken or condemned for a public or quasi-public use (a sale in lieu
of condemnation to be deemed a taking or condemnation for purposes of this
Lease), this Lease shall, at either party's option, terminate as of the date
title to the condemned real estate vests in the condemnor, and the Fixed Rent
and Additional Rent herein reserved shall be apportioned and paid in full by
Tenant to Landlord to that date and all rent prepaid for period beyond that date
shall forthwith be repaid by Landlord to Tenant and neither party shall
thereafter have any liability hereunder.

            (b) If less than twenty (20%) percent of the floor area of the
Premises is taken or if neither Landlord nor Tenant have elected to terminate
this Lease pursuant to the preceding sentence, Landlord shall do such work as
may be reasonably necessary to restore the portion of the Premises not taken to
tenantable condition for Tenant's uses, but shall not be required to expend more
than the net award Landlord reasonably expects to be available for restoration
of the Premises. If Landlord determines that the damages available for
restoration of the Building and/or Project will not be sufficient to pay the
cost of restoration, or if the condemnation damage award is required to be
applied on account of any mortgage which encumbers any part of the Premises,
Building and/or Project, Landlord may terminate this Lease by giving Tenant
thirty (30) days prior notice specifying the termination date.

            (c) If this Lease is not terminated after any such taking or
condemnation, the Fixed Rent and the Additional Rent shall be equitably reduced
in proportion to the area of the Premises which has been taken for the balance
of the Term.

                                     -21-
<PAGE>

            (d)   If a part or all of the Premises shall be taken or condemned,
all compensation awarded upon such condemnation or taking shall go to Landlord
and Tenant shall have no claim thereto other than Tenant's damages associated
with moving, storage and relocation; and Tenant hereby expressly waives,
relinquishes and releases to Landlord any claim for damages or other
compensation to which Tenant might otherwise be entitled because of any such
taking or limitation of the leasehold estate hereby created, and irrevocably
assigns and transfers to Landlord any right to compensation of all or a part of
the Premises or the leasehold estate.

        20. ESTOPPEL CERTIFICATE. Each party agrees at any time and from time to
            --------------------
time, within ten (10) days after the other party's written request, to execute,
acknowledge and deliver to the other party a written instrument in recordable
form certifying that this Lease is unmodified and in full force and effect (or
if there have been modifications, that it is in full force and effect as
modified and stating the modifications), and the dates in which Rent, Additional
Rent, and other charges have been paid in advance, if any, and stating whether
or not to the best knowledge of the party signing such certificate, the
requesting party is in default in the performance of any covenant, agreement or
condition contained in this Lease and, if so, specifying each such default of
which the signer may have knowledge. It is intended that any such certification
and statement delivered pursuant to this Article may be relied upon by any
prospective purchaser of the fee or any mortgagee thereof or any assignee of
Landlord's interest in this Lease or of any mortgage upon the fee of the
Premises or any part thereof.

        21. DEFAULT.
            -------
            If:

            (i)   Tenant fails to pay any installment of Fixed Rent or any
amount of Additional Rent when due,

            (ii)  Tenant "vacates" the Premises (other than in the case of a
permitted subletting or assignment) or permits the same to be unoccupied,

            (iii) Tenant fails to observe or perform any of Tenant's other
agreements or obligations herein contained within thirty (30) days after written
notice specifying the default, or the expiration of such additional time period
as is reasonably necessary to cure such default, provided Tenant immediately
commences and thereafter proceeds with all due diligence and in good faith to
cure such default,

            (iv)  Tenant makes any assignment for the benefit of creditors,

            (v)   Tenant commits an act of federal or state bankruptcy or files
a petition or commences any proceeding under any bankruptcy or insolvency law,

            (vi)  a petition is filed or any proceeding is commenced against
Tenant under any federal or state bankruptcy or insolvency law and such petition
or proceeding is not dismissed within thirty (30)

                                     -22-
<PAGE>

days,

            (vii)  Tenant is adjudicated a bankrupt,

            (viii) Tenant by any act indicates its consent to, approval of or
acquiescence in, or a court approves, a petition filed or proceeding commenced
against Tenant under any federal or state bankruptcy or insolvency law,

            (ix)   a receiver or other official is appointed for Tenant or for
a substantial part of Tenant's assets or for Tenant's interests in this Lease,

            (x)    any attachment or execution against a substantial part of
Tenant's assets or of Tenant's interests in this Lease remains unstayed or
undismissed for a period of more than ten (10) days, or

            (xi)   a substantial part of Tenant's assets or of Tenant's
interest in this Lease is taken by legal process in any action against Tenant,

then, in any such event, an Event of Default shall be deemed to exist and Tenant
shall be in default hereunder.

        If an Event of Default shall occur, the following provisions shall apply
and Landlord shall have, in addition to all other rights and remedies available
at law or in equity, the rights and remedies set forth therein, which rights and
remedies may be exercised upon or at any time following the occurrence of an
Event of Default unless, prior to such exercise, Landlord shall agree in writing
with Tenant that the Event(s) of Default has been cured by Tenant in all
respects.

            (a)    Acceleration of Rent. By notice to Tenant, Landlord shall
                   --------------------
have the right to accelerate all Fixed Rent and all expense installments due
hereunder and otherwise payable in installments over the remainder of the Term,
and, at Landlord's option, any other Additional Rent to the extent that such
Additional Rent can be determined and calculated to a fixed sum; and the amount
of accelerated rent to the termination date, without further notice or demand
for payment, shall be due and payable by Tenant within five (5) days after
Landlord has so notified Tenant, such amount collected from Tenant pursuant to a
judgment shall be discounted to present value using an interest rate of ten
percent (10%) per annum. Additional Rent which has not been included, in whole
or in part, in accelerated rent, shall be due and payable by Tenant during the
remainder of the Term, in the amounts and at the times otherwise provided for in
this Lease.

        Notwithstanding the foregoing or the application of any rule of law
based on election of remedies or otherwise, if Tenant fails to pay the
accelerated rent in full when due, Landlord thereafter shall have the right by
notice to Tenant, (i) to terminate Tenant's further right to possession of the
Premises and (ii) to terminate this Lease under paragraph (b) below; and if
Tenant shall have paid part but not all of the accelerated rent, the portion
thereof attributable to the period equivalent to the part of

                                     -23-
<PAGE>

the Term remaining after Landlord's termination of possession or termination of
this Lease shall be applied by Landlord against Tenant's obligations owing to
Landlord, as determined by the applicable provisions of paragraphs (c) and (d)
below.

               (b) Termination of Lease. By notice to Tenant, Landlord shall
                   --------------------
have the right to terminate this Lease as of a date specified in the notice of
termination and in such case, Tenant's rights, including any based on any option
to renew, to the possession and use of the Premises shall end absolutely as of
the termination date; and this Lease shall also terminate in all respects except
for the provisions hereof regarding Landlord's damages and Tenant's liabilities
arising prior to, out of and following the Event of Default and the ensuing
termination.

        Following such termination and the notice of same provided above (as
well as upon any other termination of this Lease by expiration of the Term or
otherwise) Landlord immediately shall have the right to recover possession of
the Premises; and to that end, Landlord may enter the Premises and take
possession, without the necessity of giving Tenant any notice to quit or any
other further notice, with or without legal process or proceedings, and in so
doing Landlord may remove Tenant's property (including any improvements or
additions to the Premises which Tenant made, unless made with Landlord's consent
which expressly permitted Tenant to not remove the same upon expiration of the
Term), as well as the property of others as may be in the Premises, and make
disposition thereof in such manner as Landlord may deem to be commercially
reasonable and necessary under the circumstances.

               (c) Tenant's Continuing Obligations/Landlord's Reletting Rights.
                   -----------------------------------------------------------

                   (1)    Unless and until Landlord shall have terminated this
Lease under paragraph (b) above, Tenant shall remain fully liable and
responsible to perform all of the covenants and to observe all the conditions of
this Lease throughout the remainder of the Term to the early termination date;
and, in addition, Tenant shall pay to Landlord, upon demand and as Additional
Rent, the total sum of all costs, losses and expenses, including reasonable
attorneys' fees, as Landlord incurs, directly or indirectly, because of any
Event of Default having occurred.

                   (2)    If Landlord either terminates Tenant's right to
possession without terminating this Lease or terminates this Lease and Tenant's
leasehold estate as above provided, then, subject to the provisions below,
Landlord shall have the unrestricted right to relet the Premises or any part(s)
thereof to such tenant(s) on such provisions and for such period(s) as Landlord
may deem appropriate. Landlord agrees, however, to use best efforts to mitigate
its damages, provided that Landlord shall not be liable to Tenant for its
inability to mitigate damages if it shall endeavor to relet the Premises in like
manner as it offers other comparable vacant space or property available for
leasing to others in the Project of which the Building is a part. If Landlord
relets the Premises after such a default, the costs recovered from Tenant shall
be reallocated to take into consideration any additional rent which Landlord
receives from the new tenant which is in excess to that which was owed by
Tenant.

                                     -24-
<PAGE>

               (d)  Landlord's Damages.
                    ------------------

                    (1)    The damages which Landlord shall be entitled to
recover from Tenant shall be the sum of:

                           (A)    all Fixed Rent and Additional Rent accrued and
unpaid as of the termination date; and

                           (B)    (i) all costs and expenses incurred by
Landlord in recovering possession of the Premises, including removal and storage
of Tenant's property, (ii) the costs and expenses of restoring the Premises to
the condition in which the same were to have been surrendered by Tenant as of
the expiration of the Term, and (iii) the costs of reletting commissions; and

                           (C)    all Fixed Rent and Additional Rent (to the
extent that the amount(s) of Additional Rent has been then determined) otherwise
payable by Tenant over the remainder of the Term as reduced to present value.

Less deducting from the total determined under subparagraphs (A), (B) and (C)
all Rent and all other Additional Rent to the extent determinable as aforesaid,
(to the extent that like charges would have been payable by Tenant) which
Landlord receives from other tenant(s) by reason of the leasing of the Premises
or part during or attributable to any period falling within the otherwise
remainder of the Term.

                    (2)    The damage sums payable by Tenant under the preceding
provisions of this paragraph (d) shall be payable on demand from time to time as
the amounts are determined; and if from Landlord's subsequent receipt of rent as
aforesaid from reletting, there be any excess payment(s) by Tenant by reason of
the crediting of such rent thereafter received, the excess payment(s) shall be
refunded by Landlord to Tenant, without interest.

                    (d)    Landlord may distrain for rent, and enforce the
provisions of this Lease and may enforce and protect the rights of Landlord
hereunder by a suit or suits in equity or at law for the specific performance of
any covenant or agreement contained herein, and for the enforcement of any other
appropriate legal or equitable remedy, including, without limitation, injunctive
relief, and for recovery of all moneys due or to become due from Tenant under
any of the provisions of this Lease.

                    (e)    Without limiting the generality of the foregoing, if
Tenant shall be in default in the performance of any of its obligations
hereunder, Landlord, without being required to give Tenant any notice or
opportunity to cure, may (but shall not be obligated to do so), in addition to
any other rights it may have in law or in equity, cure such default on behalf of
Tenant, and Tenant shall reimburse Landlord upon demand for any sums paid or
costs incurred by Landlord in curing such default, including reasonable
attorneys' fees and other legal expenses, together with interest at 10% per
annum Rate from the dates of Landlord's incurring of costs or expenses.

                                     -25-
<PAGE>

               Tenant further waives the right to any notices to quit as may be
specified in the Landlord and Tenant Act of Pennsylvania, Act of April 6, 1951,
as amended, or any similar or successor provision of law, and agrees that five
days notice shall be sufficient in any case where a longer period may be
statutorily specified.

               (f)    In addition to, and not in lieu of any of the foregoing
rights granted to Landlord;

                      (i)    TENANT HEREBY EMPOWERS ANY PROTHONOTARY, CLERK
OF COURT OR ATTORNEY OF ANY COURT OF RECORD TO APPEAR FOR TENANT IN ANY AND ALL
ACTIONS WHICH MAY BE BROUGHT FOR ANY RENT, OR ANY CHARGES HEREBY RESERVED OR
DESIGNATED AS RENT OR ANY OTHER SUM PAYABLE BY TENANT TO LANDLORD UNDER OR BY
REASON OF THIS LEASE (INCLUDING, WITHOUT LIMITATION, ANY SUM PAYABLE UNDER
SUBDIVISION (A) OR SUBDIVISION (C) ABOVE IN THIS PARAGRAPH), AND TO SIGN FOR
TENANT AN AGREEMENT FOR ENTERING IN ANY COMPETENT COURT AN ACTION OR ACTIONS FOR
THE RECOVERY OF SAID RENT, CHARGES AND OTHER SUMS, AND IN SAID SUIT OR IN SAID
ACTION OR ACTIONS TO CONFESS JUDGMENT AGAINST TENANT FOR ALL OR ANY PART OF THE
RENT SPECIFIED IN THIS LEASE AND THEN UNPAID INCLUDING, AT LANDLORD'S OPTION,
THE RENT FOR THE ENTIRE UNEXPIRED BALANCE OF THE TERM OF THIS LEASE, AND ALL OR
ANY PART OF ANY OTHER OF SAID CHARGES OR SUMS, AND FOR INTEREST AND COSTS
TOGETHER WITH REASONABLE ATTORNEY'S FEES OF 5%. SUCH AUTHORITY SHALL NOT BE
EXHAUSTED BY ONE EXERCISE THEREOF, BUT JUDGMENT MAY BE CONFESSED AS AFORESAID
FROM TIME TO TIME AS OFTEN AS ANY OF SAID RENT OR SUCH OTHER SUMS, CHARGES,
PAYMENTS, COSTS AND EXPENSES SHALL FALL DUE OR BE IN ARREARS, AND SUCH POWERS
MAY BE EXERCISED AS WELL AFTER THE EXPIRATION OF THE TERM OR DURING ANY
EXTENSION OR RENEWAL OF THIS LEASE.

                      (ii)   WHEN THIS LEASE OR TENANT'S RIGHT OF POSSESSION
SHALL BE TERMINATED BY COVENANT OR CONDITION BROKEN, OR FOR ANY OTHER REASON,
EITHER DURING THE TERM OF THIS LEASE OR ANY RENEWAL OR EXTENSION THEREOF, AND
ALSO WHEN AND AS SOON AS THE TERM HEREBY CREATED OR ANY EXTENSION THEREOF SHALL
HAVE EXPIRED, IT SHALL BE LAWFUL FOR ANY ATTORNEY AS ATTORNEY FOR TENANT TO FILE
AN AGREEMENT FOR ENTERING IN ANY COMPETENT COURT AN ACTION TO CONFESS JUDGMENT
IN EJECTMENT AGAINST TENANT AND ALL PERSONS CLAIMING UNDER TENANT, WHEREUPON,
IF LANDLORD SO DESIRES, A WRIT OF EXECUTION OR OF POSSESSION MAY ISSUE
FORTHWITH, WITHOUT ANY PRIOR WRIT OF PROCEEDINGS, WHATSOEVER, AND PROVIDED THAT
IF FOR ANY REASON AFTER SUCH ACTION SHALL HAVE BEEN COMMENCED THE SAME SHALL BE
DETERMINED AND THE POSSESSION OF THE PREMISES HEREBY DEMISED REMAIN IN OR BE
RESTORED TO TENANT, LANDLORD SHALL HAVE THE RIGHT UPON ANY SUBSEQUENT DEFAULT OR
DEFAULTS, OR UPON THE TERMINATION OF THIS LEASE AS HEREINBEFORE SET FORTH, TO
BRING ONE OR MORE ACTION OR ACTIONS AS

                                     -26-
<PAGE>

HEREINBEFORE SET FORTH TO RECOVER POSSESSION OF THE SAID PREMISES.

               In any action to confess judgment in ejectment or for rent in
arrears, Landlord shall first cause to be filed in such action an affidavit made
by it or someone acting for it setting forth the facts necessary to authorize
the entry of judgment, of which facts such affidavit shall be conclusive
evidence, and if a true copy of this Lease (and of the truth of the copy such
affidavit shall be sufficient evidence) be filed in such action, it shall not be
necessary to file the original as a warrant of attorney, any rule of Court,
custom or practice to the contrary notwithstanding.

      ________(INITIAL). TENANT WAIVER. TENANT SPECIFICALLY ACKNOWLEDGES THAT
TENANT HAS VOLUNTARILY, KNOWINGLY AND INTELLIGENTLY WAIVED CERTAIN DUE PROCESS
RIGHTS TO A PREJUDGMENT HEARING BY AGREEING TO THE TERMS OF THE FOREGOING
PARAGRAPHS REGARDING CONFESSION OF JUDGMENT. TENANT FURTHER SPECIFICALLY AGREES
THAT IN THE EVENT OF DEFAULT, LANDLORD MAY PURSUE MULTIPLE REMEDIES INCLUDING
OBTAINING POSSESSION PURSUANT TO A JUDGMENT BY CONFESSION AND ALSO OBTAINING A
MONEY JUDGEMENT FOR PAST DUE AND ACCELERATED AMOUNTS AND EXECUTING UPON SUCH
JUDGMENT. IN SUCH EVENT AND SUBJECT TO THE TERMS SET FORTH HEREIN, LANDLORD
SHALL PROVIDE FULL CREDIT TO TENANT FOR ANY MONTHLY CONSIDERATION WHICH LANDLORD
RECEIVES FOR THE LEASED PREMISES IN MITIGATION OF ANY OBLIGATION OF TENANT TO
LANDLORD FOR THAT MONEY. FURTHERMORE, TENANT SPECIFICALLY WAIVES ANY CLAIM
AGAINST LANDLORD AND LANDLORD'S COUNSEL FOR VIOLATION OF TENANT'S CONSTITUTIONAL
RIGHTS IN THE EVENT THAT JUDGMENT IS CONFESSED PURSUANT TO THIS LEASE.

               (g)  Interest on Damage Amounts. Any sums payable by Tenant
                    --------------------------
hereunder, which are not paid after the same shall be due, shall bear interest
from that day until paid at the rate of four (4%) percent over the then Prime
Rate as published daily under the beading "Money Rates" in The Wall Street
                                                           ---------------
Journal, unless such rate be usurious as applied to Tenant, in which case the
-------
highest permitted legal rate shall apply (the "Default Rate").

               (h)  Landlord's Statutory Rights. Landlord shall have all rights
                    ---------------------------
and remedies now or hereafter existing at law or in equity with respect to the
enforcement of Tenant's obligations hereunder and the recovery of the Premises.
No right or remedy herein conferred upon or reserved to Landlord shall be
exclusive of any other right or remedy, but shall be cumulative and in addition
to all other rights and remedies given hereunder or now or hereafter existing at
law. Landlord shall be entitled to injunctive relief in case of the violation,
or attempted or threatened violation, of any covenant, agreement, condition or
provision of this Lease, or to a decree compelling performance of any covenant,
agreement, condition or provision of this Lease.

               (i)  Remedies Not Limited. Nothing herein contained shall limit
                    --------------------
or prejudice the right of Landlord to exercise any or all rights and remedies
available to Landlord by reason of default or

                                     -27-
<PAGE>

to prove for and obtain in proceedings under any bankruptcy or insolvency laws,
an amount equal to the maximum allowed by any law in effect at the time when,
and governing the proceedings in which, the damages are to be proved, whether or
not the amount be greater, equal to, or less than the amount of the loss or
damage referred to above.

               (j)  No Waiver by Landlord. No delay or forbearance by landlord
                    ---------------------
in exercising any right or remedy hereunder, or Landlord's undertaking or
performing any act or matter which is not expressly required to be undertaken by
Landlord shall be construed, respectively, to be a waiver of Landlord's rights
or to represent any agreement by Landlord to undertake or perform such act or
matter thereafter. Waiver by Landlord of any breach by Tenant of any covenant or
condition herein contained (which waiver shall be effective only if so expressed
in writing by Landlord) or failure by Landlord to exercise any right or remedy
in respect of any such breach shall not constitute a waiver or relinquishment
for the future of Landlord's right to have any such covenant or condition duly
performed or observed by Tenant, or of Landlord's rights arising because of any
subsequent breach of any such covenant or condition nor bar any right or remedy
of Landlord in respect of such breach or any subsequent breach. Landlord's
receipt and acceptance of any payment from Tenant which is tendered not in
conformity with the provisions of this Lease or following an Event of Default
(regardless of any endorsement or notation on any check or any statement in any
letter accompanying any payment) shall not operate as an accord and satisfaction
or a waiver of the right of Landlord to recover any payments then owing by
Tenant which are not paid in full, or act as a bar to the termination of this
Lease and the recovery of the Premises because of Tenant's previous default.

           22. CURING TENANT'S DEFAULTS. If Tenant shall default in its monetary
               ------------------------
performance of over ten (10) days and of any of its non-monetary obligations
hereunder, Landlord without prejudice and in addition to any other rights it may
have at law or in equity, after giving Tenant written notice of such default and
after failure by Tenant within thirty (30) days of the receipt of such notice to
correct or to undertake and diligently pursue correction of said default(s) in
which event the thirty day period shall be extended for a reasonable time not to
exceed an additional fifteen (15) days (which notice and/or opportunity to cure
shall not be required in case Landlord shall determine that an emergency exists
requiring prompt action), may cure such defaults(s) on behalf of Tenant; and
Tenant shall reimburse Landlord on demand for all costs incurred by Landlord in
that regard plus interest thereon from the date(s) of expenditure at the Default
Rate, which shall be deemed Additional Rent payable hereunder.

           23. LANDLORD'S LIEN. Intentionally Deleted.
               ---------------

           24. LANDLORD'S REPRESENTATIONS AND WARRANTIES. Landlord represents
               -----------------------------------------
and warrants to Tenant as follows:

               (1)    Landlord is the fee owner of the Building and the Project;
                      and

               (2)    Landlord has the authority to enter into this Lease.

           25. SURRENDER. Tenant shall, at the expiration of the Term, promptly
               ---------
quit and surrender

                                     -28-
<PAGE>

the Premises in good order and condition and in conformity with the applicable
provisions of this Lease, excepting only reasonable wear and tear and damage by
fire or other insured casualty. Tenant shall have no right to hold over beyond
the expiration of the Term and in the event Tenant shall fail to deliver
possession of the Premises as herein provided, such occupancy shall not be
construed to effect or constitute other than a tenancy at sufferance. During any
period of occupancy beyond the expiration of the Term the amount of rent owed to
Landlord by Tenant shall automatically become two hundred percent (200%) the sum
of the Rent as those sums are at that time calculated under the provisions of
the Lease. The acceptance of rent by Landlord or the failure or delay of
Landlord in notifying or evicting Tenant following the expiration or sooner
termination of the Term shall not create any tenancy rights in Tenant and any
such payments by Tenant may be applied by Landlord against its costs and
expenses, including attorney's fees incurred by Landlord as a result of such
holdover. Landlord agrees to treat Tenant as a holdover (as opposed to a
trespasser) so long as Landlord and Tenant are negotiating in good faith to
extend the term of the Lease.

    26.   RULES AND REGULATIONS.  Tenant agrees that at all times during the
          ---------------------
terms of this Lease (as same may be extended) it, its employees, agents,
invitees and licenses shall comply with all rules and regulations specified on
Exhibit "C" attached hereto and made a part hereof, together with all reasonable
----------
Rules and Regulations as Landlord may from time to time promulgate provided they
do not increase the financial burdens of Tenant or unreasonably restrict
Tenant's rights under this Lease. Tenant's right to dispute the reasonableness
of any changes in or additions to the Rules and Regulations shall be deemed
waived unless asserted to Landlord within ten (10) business days after Landlord
shall have given Tenant written notice of any such adoption or change. In case
of any conflict or inconsistency between the provisions of this Lease and any
Rules and Regulations, the provisions of this Lease shall control. Landlord
shall have no duty or obligation to enforce any Rule and Regulation, or any
term, covenant or condition of any other lease, against any other tenant, and
Landlord's failure or refusal to enforce any Rule or Regulation or any term,
covenant of condition of any other lease against any other tenant shall be
without liability to Landlord to Tenant. However, if Landlord does enforce Rules
or Regulations, Landlord shall endeavor to enforce same equally in a non-
discriminatory manner.

    27.   GOVERNMENTAL REGULATIONS.
          ------------------------

          (a)  Tenant shall, in the use and occupancy of the Premises and the
conduct of Tenant's business or profession therein, at all times comply with all
applicable laws, ordinances, orders, notices, rules and regulations of the
federal, state and municipal governments, or any of their departments and the
regulations of the insurers of the Premises, Building and/or Project.

          (b)  Without limiting the generality of the foregoing, Tenant shall
(i) obtain, at Tenant's expense, before engaging in Tenant's business or
profession within the Premises, all necessary licenses and permits including
(but not limited to) state and local business licenses or permits, and (ii)
remain in compliance with and keep in full force and effect at all times all
licenses, consents and permits necessary for the lawful conduct of Tenant's
business or profession at the Premises. Tenant shall pay all personal property
taxes, income taxes and other taxes, assessments, duties, impositions and
similar charges which are or may be assessed, levied or imposed upon Tenant and
which, if not paid, could be

                                     -29-
<PAGE>

liened against the Premises or against Tenant's property therein or against
Tenant's leasehold estate.

          (c)  Landlord shall be responsible for compliance with Title III of
the Americans with Disabilities Act of 1990, 42 U.S.C. (S)12181 et seq. and its
                                                                -- ---
regulations, (collectively, the "ADA") (i) as to the design and construction of
exterior common areas (e.g, sidewalks and parking areas) and (ii) with respect
                       ---
to the initial design and construction by Landlord of Landlord's Work (as
defined in Article 4 hereof). Tenant shall be responsible for compliance with
the ADA in all other respects concerning the use and occupancy of the Premises,
which compliance shall include, without limitation (i) provision for full and
equal enjoyment of the goods, services, facilities, privileges, advantages or
accommodations of the Premises as contemplated by and to the extent required by
the ADA, (ii) compliance relating to requirements under the ADA or amendments
thereto arising after the date of this Lease and (iii) compliance relating to
the design, layout, renovation, redecorating, refurbishment, alteration, or
improvement to the Premises made or requested by Tenant at any time following
completion of the Landlord's Work.

          (d)  Tenant, subject to the limitation of liability set forth herein,
shall indemnify, protect, defend and save Landlord harmless with regard to any
non-compliance or alleged non-compliance by Tenant with any law, order,
ordinance, regulation, permit, license or other governmental matter in any way
relating to the conduct of Tenant's business or profession in the Premises. If
Landlord is named as defendant or a responsible party with respect to any
alleged violation or non-compliance by Tenant as aforesaid, Landlord also may
require, by notice to Tenant, that the matters or conduct giving rise thereto be
discontinued by Tenant unless and until the alleged violation or non-compliance
is resolved in Tenant's favor.

     28.  NOTICES. Wherever in this Lease it shall be required or permitted that
          -------
notice or demand be given or served by either party to this Lease to or on the
other party, such notice or demand shall be deemed to have been duly given or
served if in writing and either: (i) personally served; (ii) delivered by pre-
paid nationally recognized overnight courier service (e.g. Federal Express) with
                                                      ----
evidence of receipt required for delivery; or (iii) forwarded by Registered or
Certified mail, return receipt requested, postage prepaid; in all such cases
addressed to the parties at the addresses set forth in Article 1 (m) hereof.
Each such notice shall be deemed to have been given to or served upon the party
to which addressed on the date the same is delivered or delivery is refused.
Either party hereto may change its address to which said notice shall be
delivered or mailed by giving written notice of such change to the other party
hereto, as herein provided.

     29.  BROKERS.  Tenant represents and warrants to Landlord that Tenant has
          -------
had no dealings, negotiations or consultations with respect to the Premises or
this transaction with any broker or finder other than the Broker identified in
Article 1(k); and that otherwise no broker or finder called the Premises to
Tenant's attention for lease or took any part in any dealings, negotiations or
consultations with respect to the Premises or this Lease. Each party agrees to
indemnify and hold the other harmless from and against all liability, cost and
expense, including attorney's fees and court costs, arising out of any
misrepresentation or breach of warranty under this Article.

                                     -30-
<PAGE>

     30.  CHANGE OF BUILDING/PROJECT NAME. Landlord reserves the right at any
          -------------------------------
time and from time to time to change the name by which the Building and/or
Project is designated. Landlord agrees to pay for the reasonably documented
costs of stationery charges (including letterhead and cards) necessitated by any
such name change.

     31.  LANDLORD'S LIABILITY.  Landlord's obligations hereunder shall be
          --------------------
binding upon Landlord only for the period of time that Landlord is in ownership
of the Building; and, upon termination of that ownership, Tenant, except as to
any obligations which have then due and owing, shall look solely to Landlord's
successor in interest in the Building for the satisfaction of each and every
obligation of Landlord hereunder. Landlord shall have no personal liability
under any of the terms, conditions or covenants of this Lease and Tenant shall
look solely to the equity of Landlord in the Building of which the Premises form
a part for the satisfaction of any claim, remedy or cause of action accruing to
Tenant as a result of the breach of any action of this Lease by Landlord. In
addition to the foregoing, no recourse shall be had for an obligation of
Landlord hereunder, or for any claim based thereon or otherwise in respect
thereof, against any past, present of future trustee, shareholder, officer,
director, agent or employee of Landlord, whether by virtue of any statute or
rule of law, or by the enforcement of any assessment or penalty or otherwise,
all such other liability being expressly waived and released by Tenant with
respect to the above-named individuals.

     32.  AUTHORITY.  Tenant represents and warrants that (a) Tenant is duly
          ---------
organized, validly existing and legally authorized to do business in the
Commonwealth of Pennsylvania, and (b) the persons executing this Lease are duly
authorized to execute and deliver this Lease on behalf of Tenant.

     33.  NO OFFER.  The submission of the Lease by Landlord to Tenant for
          --------
examination does not constitute a reservation of or option for the Premises or
of any other space within the Building or in other buildings owned or managed by
Landlord or its affiliates. This Lease shall become effective as a Lease only
upon the execution and legal delivery thereof by both parties hereto.

     34.  RELOCATION. Landlord, at its sole expense, on at least sixty (60)
          ----------
days' prior written notice to Tenant, may require Tenant to move from the
Premises to another suite of substantially comparable size and decor in the
Building or in the Business Park in order to permit Landlord to consolidate the
Premises with other adjoining space leased or to be leased to another tenant in
the Building. In the event of any such relocation, Landlord shall pay all the
expenses of preparing and decorating the new premises so that they will be
substantially similar to the Premises and shall also pay the expenses of moving
Tenant's furniture and equipment to the new premises.

     35.  MISCELLANEOUS PROVISIONS.
          ------------------------

          A.   Successors.  The respective rights and obligations provided in
               ----------
this Lease shall bind and inure to the benefit of the parties hereto, their
successors and assigns; provided, however, that no rights shall inure to the
benefit of any successors of Tenant unless Landlord's written consent for the
transfer to such successor and/or assignee has first been obtained as provided
in Article 16 hereof.

                                     -31-
<PAGE>

          B.   Governing Law.  This Lease shall be construed, governed and
               -------------
enforced in accordance with the laws of the Commonwealth of Pennsylvania,
without regard to principles relating to conflicts of law.

          C.   Severability.  If any provisions of this Lease shall be held to
               ------------
be invalid, void or unenforceable, the remaining provisions hereof shall in no
way be affected or impaired and such remaining provisions shall remain in full
force and effect.

          D.   Captions.  Marginal captions, titles or exhibits and riders and
               --------
the table of contents in this Lease are for convenience and reference only, and
are in no way to be construed as defining, limiting or modifying the scope of
intent of the various provisions of this Lease.

          E.   Gender. As used in this Lease, the word "person" shall mean and
               ------
include, where appropriate, an individual, corporation, partnership or other
entity; the plural shall be substituted for the singular, and the singular for
the plural, where appropriate; and the words of any gender shall mean to include
any other gender.

          F.   Entire Agreement.  This Lease, including the Exhibits and any
               ----------------
Riders hereto (which are hereby incorporated by this reference, except that in
the event of any conflict before the printed portions of this Lease and any
Exhibits or Riders, the term of such Exhibits or Riders shall control),
supersedes any prior discussions, proposals, negotiations and discussions
between the parties and the Lease contains all the agreements, conditions,
understandings, representations and warranties made between the parties hereto
with respect to the subject matter hereof, and may not be modified orally or in
any manner other than by an agreement in writing signed by both parties hereto
or their respective successors in interest. Without in any way limiting the
generality of the foregoing, this Lease can only be extended pursuant to the due
exercise of an option (if any) contained herein or a formal agreement signed by
both Landlord and Tenant specifically extending the terms. No negotiations,
correspondence by Landlord or offers to extend the terms shall be deemed an
extension of the termination date for any period whatsoever.

          G.   Counterparts. This Lease may be executed in any number of
               ------------
counterparts, each of which when taken together shall be deemed to be one and
the same instrument.

          H.   Telefax Signatures. The parties acknowledge and agree that
               ------------------
notwithstanding any law or presumption to the contrary a telefaxed signature of
either party whether upon this Lease or any related document shall be deemed
valid and binding and admissible by either party against the other as if same
were an original ink signature.

          I.   Calculation of Time. In computing any period of time prescribed
               -------------------
or allowed by any provision of this lease, the day of the act, event or default
from which the designated period of time begins to run shall not be included.
The last day of the period so computed shall be included, unless it is a
Saturday, Sunday or a legal holiday, in which event the period runs until the
end of the next day which

                                     -32-
<PAGE>

is not a Saturday, Sunday, or legal holiday. Unless otherwise provided herein,
all Notices and other periods expire as of 5:00 p.m. (local time in Newtown
Square, Pennsylvania) on the last day of the Notice or other period.

          J.   No Merger. There shall be no merger of this Lease or of the
               ---------
leasehold estate hereby created with the fee estate in the Premises or any part
thereof by reason of the fact that the same person, firm, corporation, or other
legal entity may acquire or hold, directly or indirectly, this Lease of the
leasehold estate and the fee estate in the Premises or any interest in such fee
estate, without the prior written consent of Landlord's mortgagee.

          K.   Time of the Essence. Time is of the essence in all provisions of
               -------------------
this Lease to be performed by or on behalf of Tenant.

          L.   Recordation of Lease. Tenant shall not record this Lease without
               --------------------
the written consent of Landlord. Upon Landlord's request or with Landlord's
written consent, the parties agree to execute a short form of this Lease for
recording purposes containing such terms as Landlord believes appropriate or
desirable, the expense thereof to be borne by Tenant. If such a short form of
this Lease is recorded, upon the termination of this Lease, Tenant shall
execute, acknowledge, and deliver to Landlord an instrument in writing releasing
and quitclaiming to landlord all right, title and interest of Tenant in and to
the Premises arising from this Lease or otherwise, all without cost or expense
to Landlord.

          M.   Accord and Satisfaction. No payment by Tenant or receipt by
               -----------------------
Landlord of a lesser amount than any payment of Fixed Rent or Additional Rent
herein stipulated shall be deemed to be other than on account of the earliest
stipulated Fixed Rent or Additional Rent due and payable hereunder, nor shall
any endorsement or statement or any check or any letter accompanying any check
or payment as Rent be deemed an accord and satisfaction. Landlord may accept
such check or payment without prejudice to Landlord's right to recover the
balance of such Rent or pursue any other right or remedy provided for in this
Lease, at law or in equity.

          N.   No Partnership. Landlord does not, in any way or for any purpose,
               --------------
become a partner of Tenant in the conduct of its business, or otherwise, or
joint venturer or a member of a joint enterprise with Tenant. This Lease
establishes a relationship solely of that of a landlord and tenant.

          O.   Guaranty. In order to induce Landlord to execute this Lease,
               --------
Tenant agrees that Landlord may, at its option, at the time of the execution of
this Lease or at any time during the Term, require a guaranty of the obligations
of the Tenant hereunder by a person, firm, corporation, or other entity other
than Tenant but with a business interest in Tenant, acceptable to Landlord,
which guaranty shall be in a form satisfactory to Landlord.

     36.  RENEWAL OPTION. Provided Tenant is not in default of the Lease, either
          --------------
at the time of exercise of this option, or at the commencement of the Renewal
Term and Tenant is fully occupying the Premises and the Lease is in full force
and effect, Tenant shall have the right to renew this Lease for one (1) term of
three (3) years beyond the end of the initial Term (the "Renewal Term"). Tenant
shall

                                     -33-
<PAGE>

furnish written notice of intent to renew nine (9) months prior to the
expiration of the applicable Term, failing which, such renewal right shall be
deemed waived; time being of the essence. The terms and conditions of this Lease
during each Renewal Term shall remain unchanged except that the Base Year for
the Renewal Term shall be the first year of the applicable renewal term and the
annual Fixed Rent for the Renewal Term shall be $23.00 per rentable square foot.

     37.  WAIVER OF TRIAL BY JURY.  LANDLORD AND TENANT WAIVE THE RIGHT TO A
          -----------------------
TRIAL BY JURY IN ANY ACTION OR PROCEEDING BASED UPON, OR RELATED TO, THE SUBJECT
MATTER OF THIS LEASE. THIS WAIVER IS KNOWINGLY, INTENTIONALLY, AND VOLUNTARILY
MADE BY TENANT AND TENANT ACKNOWLEDGES THAT NEITHER LANDLORD NOR ANY PERSON
ACTING ON BEHALF OF LANDLORD HAS MADE ANY REPRESENTATIONS OF FACT TO INDUCE
THIS WAIVER OF TRIAL BY JURY OR IN ANY WAY TO MODIFY OR NULLIFY ITS EFFECT.
TENANT FURTHER ACKNOWLEDGES THAT IT HAS BEEN REPRESENTED (OR HAS HAD THE
OPPORTUNITY TO BE REPRESENTED) IN THE SIGNING OF THIS LEASE AND IN THE MAKING OF
THIS WAIVER BY INDEPENDENT LEGAL COUNSEL, SELECTED OF ITS OWN FREE WILL, AND
THAT IT HAS HAD THE OPPORTUNITY TO DISCUSS THIS WAIVER WITH COUNSEL. TENANT
FURTHER ACKNOWLEDGES THAT IT HAS READ AND UNDERSTANDS THE MEANING AND
RAMIFICATIONS OF THIS WAIVER PROVISION AND AS EVIDENCE OF SAME HAS EXECUTED THIS
LEASE.

     38.  CONSENT TO JURISDICTION.  Tenant hereby consents to the exclusive
          -----------------------
jurisdiction of the state courts located in Bucks, Montgomery, Chester, Delaware
and Philadelphia Counties and to the federal courts located in the Eastern
District of Pennsylvania.


                           INTENTIONALLY LEFT BLANK

                                     -34-
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have executed this Lease under
seal the day and year first above written.


WITNESS:                                      LANDLORD:

                                              BRANDYWINE OPERATING
                                              PARTNERSHIP, L.P.

                                              By:   Brandywine Realty Trust,
                                                    its general partner



/s/ [ILLEGIBLE]^^                             By: /s/ [ILLEGIBLE]^^
-------------------------------                   ------------------------------
H. Jeffrey DeVuono                                Gerard H. Sweeney,
Vice President - Operations                       President and CEO



WITNESS:                                      TENANT:

                                              U S WATS, INC.
                                              a New York Corporation

                                              By: /s/ [ILLEGIBLE]^^
_______________________________                   ------------------------------
Authorized Representative                         Authorized Representative

                                     -35-