<PAGE>

                                      LEASE

                                   SEARS TOWER

                             233 SOUTH WACKER DRIVE

                                CHICAGO, ILLINOIS

                             UNIVERSAL ACCESS, INC.

<PAGE>

                                      LEASE

                                   SEARS TOWER

                             233 SOUTH WACKER DRIVE

                                CHICAGO, ILLINOIS

                             UNIVERSAL ACCESS, INC.

<TABLE>
<CAPTION>

                                                                                                               PAGE
                                                                                                               ----
                                TABLE OF CONTENTS

<S>                                                                                                            <C>
SCHEDULE..........................................................................................................1

TERMS AND CONDITIONS..............................................................................................5

1.    TERM........................................................................................................5
2.    BASE RENT...................................................................................................5
3.    ADDITIONAL RENT.............................................................................................5
4.    USE OF THE PREMISES........................................................................................11
5.    POSSESSION.................................................................................................12
6.    SERVICES...................................................................................................13
7.    REPAIRS....................................................................................................17
8.    ADDITIONS AND ALTERATIONS..................................................................................18
9.    COVENANT AGAINST LIENS.....................................................................................19
10.   INSURANCE..................................................................................................19
11.   FIRE OR CASUALTY...........................................................................................21
12.   WAIVER OF CLAIMS - INDEMNIFICATION.........................................................................22
13.   NONWAIVER..................................................................................................23
14.   CONDEMNATION...............................................................................................23
15.   ASSIGNMENT AND SUBLETTING..................................................................................24
16.   SURRENDER OF POSSESSION....................................................................................27
17.   HOLDING OVER...............................................................................................28
18.   ESTOPPEL CERTIFICATE.......................................................................................29
19.   OBLIGATIONS TO MORTGAGEES..................................................................................29
20.   CERTAIN RIGHTS RESERVED BY LANDLORD........................................................................30
21.   RULES AND REGULATIONS......................................................................................32
22.   DEFAULT AND LANDLORD'S REMEDIES............................................................................32
23.   EXPENSES OF ENFORCEMENT....................................................................................34
24.   COVENANT OF QUIET ENJOYMENT................................................................................34
25.   REAL ESTATE BROKER.........................................................................................35
26.   MISCELLANEOUS..............................................................................................35
27.   NOTICES....................................................................................................39
28.   LIMITATION OF LIABILITY....................................................................................40
29.   SECURITY DEPOSIT...........................................................................................40
30.   RIGHT OF FIRST OFFER.......................................................................................43
31.   EXPANSION OF PREMISES......................................................................................43


                                      i
<PAGE>

32.   TENANT'S OPTION TO RENEW...................................................................................44
</TABLE>


                                    EXHIBITS

         EXHIBIT A         FLOOR PLAN OF PREMISES

         EXHIBIT B         TENANT WORK LETTER

         EXHIBIT C         RULES AND REGULATIONS

         EXHIBIT D         ESTOPPEL CERTIFICATE

         EXHIBIT E         CONDENSER WATER ADDENDUM

         EXHIBIT F         GENERATOR LOCATION

         EXHIBIT G         SIGNAGE


                                      ii
<PAGE>

                                      LEASE
                                   SEARS TOWER
                             233 SOUTH WACKER DRIVE
                                CHICAGO, ILLINOIS

         THIS AGREEMENT OF LEASE made as of this 10th day of March, 2000
(hereinafter referred to as the "Lease") between TH TOWER LEASING LLC, a
Delaware limited liability company (hereinafter referred to as "Landlord"), and
UNIVERSAL ACCESS, INC., a Delaware corporation (hereinafter referred to as
"Tenant");


                                    SCHEDULE


1.       DESCRIPTION OF PREMISES: The premises designated on the plans attached
         hereto as Exhibits A-1-A-6, respectively, and containing approximately
         18,378 square feet of Rentable Area on the 3rd floor (the "Third Floor
         Premises") consisting of the 7,295 square feet of the Rentable Area
         identified on Exhibit A-1 and herein as the "Phase 1 - 3rd Floor Space"
         and the 11,083 square feet of Rentable Area identified on Exhibit A-1
         and herein as the "Phase 2 - 3rd Floor Space" (the Phase 1 - 3rd Floor
         Space and the Phase 2 - 3rd Floor Space are herein sometimes together
         referred to as the "Third Floor Premises"); 14,284 square feet of
         Rentable Area on the 4th floor identified on Exhibit A-2 and herein as
         the "Fourth Floor Premises"; 50,033 square feet of Rentable Area on the
         5th floor consisting of the 20,885 square feet of Rentable Area
         identified on Exhibit A-3 and herein as the "Phase 1 - 5th Floor Space"
         and the 29,148 square feet of Rentable Area identified on Exhibit A-3
         and herein as the "Phase 2 - 5th Floor Space" (the Phase 1 - 5th Floor
         Space and the Phase 2 - 5th Floor Space are herein sometimes together
         referred to as the "Fifth Floor Premises"); 50,033 square feet of
         Rentable Area on the 6th floor identified on Exhibit A-4 and herein as
         the "Sixth Floor Premises"; 2,606 square feet of Rentable Area on the
         7th floor identified on Exhibit A-5 and herein as the "Seventh Floor
         Premises"; and 37,084 square feet of Rentable Area on the 8th floor
         identified on Exhibit A-6 and herein as the "Eighth Floor Premises";
         the Third Floor Premises, the Fourth Floor Premises, the Fifth Floor
         Premises, the Sixth Floor Premises, the Seventh Floor Premises and the
         Eighth Floor Premises are sometimes herein collectively referred to as
         the "Premises", in the building commonly known as the Sears Tower (the
         "Building") located at 233 South Wacker Drive in the City of Chicago,
         Cook County, Illinois (hereinafter referred to together with all
         present and future easements, additions, improvements and other rights
         appurtenant thereto, as the "Land").

2.       USE OF PREMISES: Tenant shall use the Premises solely as general
         offices and for no other purpose whatsoever; provided, however, that
         Tenant may use the Seventh Floor Premises for a Network Operating
         Center and/or Universal Transport Exchange, but may not use the
         Universal Transport Exchange to circumvent the obligation of all
         service providers in the Building to pay fees for access to the
         Building in accordance with individual license agreements.

3.       BASE RENT: The per annum rate of Base Rent and the monthly installments
         thereof are set forth on Schedule 1 attached hereto.

<PAGE>

4.       TENANT'S PROPORTIONATE SHARE: shall mean (a) 4.64% for the purposes of
         determining Taxes (as hereinafter defined) payable by Tenant hereunder,
         such percentage being the percentage calculated by dividing the
         Rentable Area contained in the Premises, as determined by Landlord and
         shown in Item 1 of this Schedule by 3,716,292 rentable square feet
         (being one hundred percent (100%) of the aggregate amount of all office
         and retail space in the Building), and (b) 4.99% for purposes of
         determining Operating Expenses (as hereafter defined) payable by Tenant
         hereunder, such percentage being the percentage calculated by dividing
         the Rentable Area of the Premises, by 3,457,851 rentable square feet
         (being one hundred percent (100%) of the aggregate amount of all office
         space in the Building). Tenant's Proportionate Share shall be adjusted
         proportionately if the number of square feet of Rentable Area in the
         Premises is increased or decreased or if the aggregate amount of office
         or retail space in the Building is either increased or decreased.
         Tenant's Proportionate Share will be adjusted to reflect the staged
         take down of the space and Tenant shall not be responsible for Tenant's
         Proportionate Share of Taxes or Operating Expenses for any portion of
         the Premises until the Rent Commencement Date for such portion of the
         Premises occurs.

5.       COMMENCEMENT DATE:  The date hereof.

6.       TERMINATION DATE:  July 31, 2012.

7.       SECURITY DEPOSIT: Seven Million Five Hundred Thousand and 00/100
         Dollars ($7,500,000.00) increasing and decreasing as provided in
         Section 29 of the Lease.

8.       ADDRESSES FOR NOTICES:

         IF TO LANDLORD:

                  TH TOWER LEASING LLC
                  c/o TrizecHahn Office Properties Inc.
                  233 South Wacker Drive, Suite 4600
                  Chicago, Illinois  60606
                  Attention:  Executive Vice President

         WITH A COPY TO:

                  TH TOWER LEASING LLC
                  c/o TrizecHahn Office Properties Inc.
                  233 South Wacker Drive, Suite 3330
                  Chicago, Illinois  60606
                  Attention:  General Manager

         IF TO TENANT:

                  PRIOR TO THE RENT COMMENCEMENT DATE:

                  UNIVERSAL ACCESS, INC.
                  100 North Riverside Plaza, Suite 2200
                  Chicago, Illinois  60606


                                      2
<PAGE>

                  Attention:  Mr. Robert Pommer

                  AFTER THE RENT COMMENCEMENT DATE:

                  UNIVERSAL ACCESS, INC.
                  233 South Wacker Drive
                  Chicago, Illinois  60606
                  Attention:  Mr. Robert Pommer

9.       BROKER:  TrizecHahn Office Properties Inc. and Dean Topping & Company.

         This Lease is subject to the Terms and Conditions and the provisions of
any exhibits attached hereto, which Terms and Conditions and exhibits are hereby
made a part of this Lease.

LANDLORD:                                                TENANT:

TH TOWER LEASING LLC,                                    UNIVERSAL ACCESS, INC.,
A DELAWARE LIMITED LIABILITY COMPANY                     A DELAWARE CORPORATION


By: /s/ Stephen E. Budorick                              By:  /s/ Robert Brown

         Its Vice President                              Its Vice President


                                      3
<PAGE>


                                   SCHEDULE 1

                                    BASE RENT



<TABLE>
<CAPTION>
                                     Per Square Foot                   Monthly                      Annual
           Period                    Base Rental Rate                 Base Rent                    Base Rent
           ------                    ----------------                 ---------                    ---------
      <S>                            <C>                             <C>                         <C>
      August 1, 2000 -
       July 31, 2001*                     $18.00                     $258,627.00                 $3,103,524.00

      August 1, 2001 -
       July 31, 2002*                     $18.54                     $266,385.81                 $3,196,629.72

      August 1, 2002 -
       July 31, 2003                      $19.10                     $274,431.98                 $3,293,183.80

      August 1, 2003 -
       July 31, 2004                      $19.67                     $282,621.84                 $3,391,462.06

      August 1, 2004 -
       July 31, 2005                      $20.26                     $291,099.06                 $3,493,188.68

      August 1, 2005 -
       July 31, 2006                      $20.87                     $299,863.64                 $3,598,363.66

      August 1, 2006 -
       July 31, 2007                      $21.50                     $308,915.58                 $3,706,987.00

      August 1, 2007 -
       July 31, 2008                      $22.15                     $318,254.89                 $3,819,058.70

      August 1, 2008 -
       July 31, 2009                      $22.81                     $327,737.88                 $3,932,854.58

      August 1, 2009 -
       July 31, 2010                      $23.49                     $337,508.24                 $4,050,098.82

      August 1, 2010 -
       July 31, 2011                      $24.19                     $347,565.95                 $4,170,791.42

      August 1, 2011 -
       July 31, 2012                      $24.92                     $358,054.71                 $4,296,656.56
</TABLE>

* Base Rent during this period will be adjusted to reflect the staged take down
of the Premises.


                                      4
<PAGE>


                              TERMS AND CONDITIONS


         Landlord hereby leases to Tenant, and Tenant hereby leases from
Landlord, the premises (hereinafter referred to as the "Premises") described in
the SCHEDULE appearing at the beginning of this Lease (hereinafter referred to
as the "SCHEDULE") and designated on the plan attached hereto as EXHIBIT A,
subject to the covenants, terms, provisions and conditions of this Lease.

1.       TERM

         The term of this Lease (hereinafter referred to as the "Term") shall
         commence on the Commencement Date and shall end on the Termination Date
         each as provided in the SCHEDULE, unless sooner terminated as provided
         herein.

2.       BASE RENT

         (a)      BASE RENT PAYMENTS. Tenant shall pay to Landlord or Landlord's
                  agent at Sears Tower, 233 South Wacker Drive, Chicago,
                  Illinois, or at such other place as Landlord or Landlord's
                  agent may from time to time designate in writing, in currency
                  which, at the time of payment, is legal tender for private or
                  public debts in the United States of America, the applicable
                  annual Base Rent set forth in SCHEDULE 1 payable for the
                  corresponding portion of the Premises, commencing on the
                  applicable Rent Commencement Date (as provided in subparagraph
                  (b) below) in equal monthly installments in the applicable
                  amounts set forth in SCHEDULE 1 in advance on or before the
                  first day of each and every month during the Term without
                  demand and without any abatement, setoff or deduction
                  whatsoever, except as specifically set forth in this Lease.
                  Such Base Rent shall be escalated as set forth in SCHEDULE 1.
                  Any Base Rent payable for a partial month other than a partial
                  month at the end of the Term shall be paid on the first day of
                  the following month. Any Base Rent payable for a partial month
                  at the end of the Term shall be paid on the first day of such
                  month.

         (b)      RENT COMMENCEMENT DATE. The applicable Rent Commencement Date
                  for each portion of the Premises shall be the earlier to occur
                  of (x) the date which is one hundred twenty (120) days
                  following the date Landlord tenders such portion of the
                  Premises to Tenant pursuant to SECTION 5 hereof and (y) the
                  date upon which Tenant begins to use for the conduct of
                  Tenant's business such portion of the Premises; provided,
                  however, that with respect to the Sixth Floor Premises the
                  Rent Commencement Date shall be the date which is one hundred
                  twenty (120) days following the date Landlord tenders the
                  Sixth Floor Premises to Tenant pursuant to SECTION 5 hereof,
                  rather than the earlier to occur of the events set forth in
                  clauses (x) and (y) of this subparagraph.

3.       ADDITIONAL RENT

         In addition to paying the Base Rent specified in SECTION 2 hereof,
         Tenant shall pay as "Additional Rent" the amounts described in this
         SECTION 3. Such Additional Rent paid by Tenant and other tenants in the
         Building shall reimburse Landlord for all expenses of owning, operating
         and maintaining the Land and the Building, except as expressly


                                      5
<PAGE>

         excluded below, and shall permit Landlord to receive the Base Rent as
         "net" rent. The Base Rent and the Additional Rent and all other amounts
         due under this Lease are herein collectively referred to as the "Rent."
         All Additional Rent shall be payable for the same periods and in the
         same manner, time and place as the Base Rent is to be paid
         notwithstanding any abatement of Base Rent. Without limitation on other
         obligations of Tenant which shall survive the expiration of the Term,
         the obligations of Tenant to pay Additional Rent shall survive the
         expiration of the Term. For any Calendar Year which is not wholly
         included in the Term, Tenant shall be obligated to pay only a pro rata
         share of the Additional Rent for such Calendar Year, based on the
         number of days of the Term falling within such Calendar Year. Except as
         specifically provided in this Lease, Rent shall be paid without
         abatement, deduction or set off of any kind (except as specifically set
         forth in this Lease), it being the intention of the parties that, to
         the full extent permitted by law, Tenant's covenant to pay Rent shall
         be independent of all other covenants contained in this Lease.

         (a)      CERTAIN DEFINITIONS.  As used in this Lease, the terms:

                  (i)      "Calendar Year" shall mean each calendar year in
                           which any part of the Term falls, through and
                           including the year in which the Term expires.

                  (ii)     "Operating Expenses" shall mean all expenses, costs
                           and disbursements of every kind and nature
                           (determined for the applicable Calendar Year on an
                           accrual basis) paid or incurred by Landlord or its
                           managing agent in connection with the ownership,
                           management, operation, maintenance and repair of the
                           Land and Building (including, without limitation, the
                           cost of providing electricity for lighting the
                           Premises as provided in Subsection 6(a)(ii) below and
                           other office space), except the following:

                           A.       Taxes (as hereinafter defined);

                           B.       Costs of capital improvements to any
                                    tenant's premises;

                           C.       Principal or interest payments on loans
                                    secured by mortgages or trust deeds on the
                                    Building or Land or rent payable on any
                                    ground lease of the Land and/or the
                                    Building;

                           D.       Costs of capital improvements to the
                                    Building, except that Operating Expenses
                                    shall include (1) the costs of any capital
                                    improvement which is intended to reduce any
                                    component of Operating Expenses and (2) the
                                    costs of any capital improvement which is
                                    made by Landlord to keep the Land or
                                    Building in compliance with all governmental
                                    rules and regulations applicable from time
                                    to time thereto (excluding such costs to
                                    comply with governmental rules and
                                    regulations in effect as of the date hereof,
                                    other than costs for the conversion of the
                                    chillers to comply with environmental
                                    regulations), in each case as evenly
                                    amortized over the useful life of each such
                                    capital improvement with interest on the
                                    unamortized amount at the greater of (A) ten
                                    percent (10%) per annum or (B) four percent
                                    (4%) per annum above the "prime rate"


                                      6
<PAGE>

                                    or "corporate base rate" announced from time
                                    to time by a major Chicago bank selected by
                                    Landlord (the "Prime Rate") (but in no event
                                    at a rate which is more than the highest
                                    lawful rate allowable in the State of
                                    Illinois);

                           E.       Costs of utilities and other services
                                    provided to and used in the operation of the
                                    retail stores in the Building, provided that
                                    the costs of operating and maintaining the
                                    common areas adjoining such retail stores at
                                    and above the Franklin Street Level shall be
                                    included in Operating Expenses; and

                           F.       Costs and expenses incurred in connection
                                    with leasing space in the Building, such as
                                    leasing commissions, tenant allowances,
                                    space planning fees and advertising and
                                    promotional expenses and legal fees for the
                                    preparation of leases;

                           G.       Costs of initial improvements to, or
                                    alterations of, space leased to any tenant;

                           H.       Depreciation or amortization of any
                                    improvements except as specifically set
                                    forth in this Lease;

                           I.       The cost of repairing or restoring any
                                    portion of the Building damaged by a hazard,
                                    to the extent Landlord has received
                                    insurance proceeds with respect to such
                                    damage (provided that the amount of any
                                    deductible paid by Landlord shall be
                                    included in Operating Expenses) or for which
                                    Landlord would have received insurance
                                    proceeds had Landlord maintained the
                                    insurance required by this Lease;

                           J.       The cost of repairs, alterations or
                                    replacements required as the result of the
                                    exercise of any right of eminent domain to
                                    the extent Landlord receives net
                                    condemnation proceeds in reimbursement of
                                    such costs, as the result of such exercise;

                           K.       Any late fees, fines, penalties and interest
                                    on past due amounts incurred by Landlord due
                                    to Landlord's violation of any applicable
                                    law, rule or regulation;

                           L.       Costs incurred for relocating tenants within
                                    the Building;

                           M.       Any other costs or expenses incurred by
                                    Landlord to the extent Landlord has actually
                                    collected funds in reimbursement of such
                                    costs and expenses (x) from any policies of
                                    insurance in effect and (y) from any other
                                    tenant (other than through such tenant's
                                    payment of its share of Operating Expenses
                                    or Taxes);

                           N.       Landlord's general corporate overhead and
                                    general administrative expenses;


                                      7
<PAGE>

                           O.       Legal and auditing fees in connection with
                                    disputes with tenants (excepting legal fees
                                    in seeking to enforce Building rules and
                                    regulations);

                           P.       Costs for services paid to any affiliate of
                                    Landlord which are in excess of the then
                                    prevailing market costs for such services;

                           Q.       Costs incurred for special services
                                    performed for other tenants which are not
                                    performed for Tenant;

                           R.       Costs of removing, encapsulating or
                                    otherwise abating any hazardous substance or
                                    regulated material (as defined under any
                                    federal, state or local law in effect as of
                                    the date hereof) in or about the Land or
                                    Building not placed there by Tenant;

                           S.       Management fees charged by Landlord or
                                    Landlord's agent to the extent such fees are
                                    in excess of management fees which would be
                                    charged in an arm's length transaction with
                                    an independent property management company;

                           T.       Executive salaries above the grade of
                                    Building Manager, except for personnel,
                                    off-site or otherwise, to the extent such
                                    personnel perform services or functions
                                    related to the management, operation or
                                    maintenance of the Building, and whose
                                    services Landlord would otherwise contract
                                    for with a third party, and then only to the
                                    extent the cost of such personnel is
                                    allocated to the Building proportionately to
                                    the amount of time spent on the Building by
                                    such personnel;

                           U.       Expenses incurred in connection with any
                                    dining club, athletic club, parking garage,
                                    observatory or antenna not available for use
                                    by Tenant without payment of an additional
                                    charge.

                  (iii)    "Taxes" shall mean taxes levied, assessed, imposed,
                           accruing or due and payable during the Term (or which
                           Landlord is obligated to pay on behalf of any other
                           person or entity having any interest in the Land or
                           the Building) in connection with the Land, the
                           Building, the operation thereof or any rights or
                           responsibilities related thereto. "Taxes" shall
                           include without limitation: (a) real estate taxes and
                           assessments, special or otherwise, levied, assessed,
                           imposed, accruing or due and payable during the Term
                           upon the Land or Building; (b) ad valorem taxes for
                           any personal property owned or leased by Landlord and
                           used exclusively in connection with operating or
                           maintaining the Land or Building; (c) any tax,
                           assessment, charge or fee which is imposed in
                           substitution for, or in lieu of an increase in, such
                           real estate taxes or ad valorem personal property
                           taxes; (d) any income or franchise tax based on
                           Landlord's income from the Land and Building which
                           taxes such income in a different manner than income
                           from sources other than the ownership and operation
                           of income-producing real estate, which is
                           substantively the functional


                                      8
<PAGE>

                           equivalent of a tax on gross rents or leases, but is
                           called by another name; or (e) a tax on gross rents
                           or leases; or (f) a tax on the development of real
                           estate or the construction or improvement of
                           buildings or premises therein. Taxes shall also
                           include, in the year paid, all fees for consultants
                           and attorneys and all other costs incurred by
                           Landlord in seeking to obtain a reduction of, or a
                           limit on the increase in, any Taxes, regardless of
                           whether any reduction or limitation is obtained.
                           Taxes shall not include any inheritance, estate,
                           succession, transfer, gift, franchise, or capital
                           stock tax or any current state or federal income
                           taxes or any income taxes other than those described
                           above. With respect to any Taxes which include
                           assessments against income or property not related to
                           the Land or Building, Taxes shall include only that
                           portion of such Taxes which would be payable if the
                           Land and Building and all rights related thereto were
                           the only assets of Landlord. Taxes shall not include
                           interest or penalties arising as a result of a late
                           payment, except to the extent such late payment is
                           due to the default of Tenant hereunder.

         (b)      EXPENSE ADJUSTMENT. Tenant shall pay to Landlord or Landlord's
                  agent as Additional Rent, an amount ("Expense Adjustment
                  Amount") equal to Tenant's Proportionate Share of the amount
                  of Operating Expenses plus Tenant's pro rata share of the
                  special allocation of Variable Operating Expenses (as defined
                  in SECTION 3(c)) incurred with respect to each Calendar Year
                  or any portion thereof. The Expense Adjustment Amount with
                  respect to each Calendar Year shall be paid in monthly
                  installments during that Calendar Year in an amount reasonably
                  estimated from time to time by Landlord and communicated by
                  written notice to Tenant. Following the close of each Calendar
                  Year, Landlord shall compute the Expense Adjustment Amount for
                  that Calendar Year based on the Operating Expenses (and any
                  special allocation of Variable Operating Expenses) for that
                  Calendar Year and shall deliver to Tenant a statement of the
                  Expense Adjustment Amount plus a statement of all estimated
                  installments paid by Tenant with respect to that Calendar
                  Year. Tenant shall pay to Landlord any deficiency shown by the
                  statement within thirty (30) days after Tenant receives the
                  statement. If the installments paid exceed the amounts due and
                  if Tenant is not then in Default under this Lease, Landlord
                  shall credit the excess against Rent or any other payment next
                  due to Landlord from Tenant hereunder and refund the excess to
                  Tenant. If Tenant is then in Default hereunder (and until
                  Tenant cures such Default), Landlord shall apply the
                  difference first to any delinquent Rent hereunder (including
                  interest thereon) and then to the next succeeding payments of
                  Rent coming due hereunder. The foregoing obligations of
                  Landlord and Tenant shall survive the expiration of the Term.
                  Delay in computation of the Expense Adjustment Amount shall
                  not be deemed a default hereunder or a waiver of Landlord's
                  right to collect the Expense Adjustment Amount. Landlord shall
                  cause to be kept books and records showing Operating Expenses
                  in accordance with an appropriate system of accounts and
                  accounting practices consistently maintained.

                  Tenant shall have the right to audit or cause to be audited by
                  a firm of certified public accountants designated by Tenant,
                  Landlord's books and records in respect


                                      9
<PAGE>

                  of Operating Expenses, the cost (including, without
                  limitation, the charges of such accountants) of which shall be
                  borne by Tenant unless it is demonstrated that Landlord has
                  overstated Tenant's Expense Adjustment Amount by more than
                  five percent (5%), in which case Landlord shall bear the cost
                  including, without limitation, the charges of such
                  accountants) of the audit. Notwithstanding anything contained
                  herein to the contrary, any audit by Tenant (or by Tenant's
                  accountants, but not by an independent consultant on a
                  contingency fee basis) of Operating Expenses for any calendar
                  year must occur during normal business hours upon at least two
                  (2) weeks prior written notice; such audit must be commenced
                  within the two (2) month period following Tenant's receipt of
                  Landlord's Statement of Operating Expenses and completed
                  within the four (4) month period following Tenant's receipt of
                  Landlord's statement of Operating Expenses. Any overpayment by
                  Tenant, if Tenant is not then in Default hereunder, shall be
                  credited against the next payment of Rent due to Landlord from
                  Tenant hereunder and if such amount exceeds the next payment
                  of Rent due Landlord from Tenant hereunder such excess shall
                  be refunded to Tenant. If Tenant is then in Default hereunder
                  (and until Tenant cures such Default), Landlord shall apply
                  the difference first to any delinquent Rent hereunder
                  (including interest thereon) and then to the next succeeding
                  payment of Rent coming due hereunder. All information obtained
                  by Tenant in connection with such audit shall be utilized by
                  Tenant and its accountants and attorneys on a confidential
                  basis and shall not be shared with other tenants in the
                  Building or their representatives.

         (c)      ALLOCATION OF VARIABLE OPERATING EXPENSES. If at any time
                  during the Term less than ninety-five percent (95%) of the
                  then current office space in the Building is occupied, at
                  Landlord's option those components of Operating Expenses which
                  vary with occupancy ("Variable Operating Expenses") shall be
                  removed from general Operating Expenses and allocated to the
                  portion of the office space in the Building which is actually
                  occupied and generating such components of Operating Expenses.
                  This special allocation shall be made on a pro rata basis over
                  the occupied office space in the Building, based on both the
                  comparative Rentable Areas of the Building which are occupied
                  and the portion of the Calendar Year during which the portions
                  of the Building were occupied. Examples of Variable Operating
                  Expenses include, without limitation, janitorial services,
                  electricity for overhead lighting and HVAC costs. Operating
                  Expenses which do not vary with occupancy, such as public
                  liability insurance and lobby maintenance will continue to be
                  allocated on a pro rata basis over the office space in the
                  Building whether or not occupied and Tenant shall only be
                  responsible for Tenant's Proportionate Share of those
                  Operating Expenses.

         (d)      TAX ADJUSTMENT. Tenant shall pay to Landlord or Landlord's
                  agent as Additional Rent, an amount ("Tax Adjustment Amount")
                  equal to Tenant's Proportionate Share of the amount of Taxes
                  incurred with respect to each Calendar Year or any portion
                  thereof. The Tax Adjustment Amount with respect to each
                  Calendar Year shall be paid in monthly installments during
                  that Calendar Year in an amount reasonably estimated from time
                  to time by Landlord and communicated by written notice to
                  Tenant. If Taxes for any Calendar Year are payable in whole or


                                     10
<PAGE>

                  in part before the end of that Calendar Year, Tenant shall,
                  within thirty (30) days after the written request of Landlord,
                  promptly pay Tenant's Proportionate Share of the payment as a
                  special installment, after deducting installments previously
                  paid by Tenant under this SECTION 3(d) for such Calendar Year.
                  Following the final payment of Taxes for each Calendar Year,
                  Landlord shall compute the Tax Adjustment Amount for that
                  Calendar Year and deliver to Tenant a statement of the Tax
                  Adjustment Amount plus a statement of all estimated
                  installments paid by Tenant for that Calendar Year. Tenant
                  shall pay to Landlord any deficiency shown by the statement
                  within thirty (30) days after Tenant receives the statement.
                  If the installments paid exceed the actual amount due and if
                  Tenant is not then in Default under this Lease, Landlord shall
                  credit the excess against Rent or any other payment next due
                  to Landlord from Tenant hereunder and refund the excess to
                  Tenant. If Tenant is then in Default hereunder (and until
                  Tenant cures such Default), Landlord shall apply the
                  difference first to any delinquent Rent hereunder (including
                  interest thereon) and then to the next succeeding payments of
                  Rent coming due hereunder. The amount of any refund of Taxes
                  received by Landlord shall be credited against Taxes for the
                  year in which such refund is received. The foregoing
                  obligations of Landlord and Tenant shall survive the
                  expiration of the Term. In determining the amount of Taxes for
                  any Calendar Year, the amount of special assessments to be
                  included shall be limited to the amount of the installment
                  (plus any interest payable thereon) of the special assessment
                  required to be paid during that year as if Landlord had
                  elected to have the special assessment paid over the maximum
                  period of time permitted by law. All references to Taxes "for"
                  a particular year shall be deemed to refer to Taxes levied or
                  assessed for the year without regard to when such Taxes are
                  paid or payable. Delay in computing the Tax Adjustment Amount
                  shall not be deemed a Default hereunder or a waiver of
                  Landlord's right to collect the Tax Adjustment Amount.

4.       USE OF THE PREMISES

         (a)      RESERVED AREAS. This Lease does not give Tenant any right to
                  use, and Landlord hereby excludes and reserves for its sole
                  and exclusive use, the following areas in and about the
                  Premises: janitor closets, stairways and stairwells, fan,
                  mechanical, electrical, telephone and similar rooms (other
                  than those installed for Tenant's exclusive use); elevator,
                  pipe and other vertical shafts, flues and ducts; all areas
                  above the acoustical ceiling and below the finished floor
                  covering installed in the Premises; all other structural or
                  mechanical elements serving other areas of the Building; and
                  all subterranean, mineral, air, light and view rights.

         (b)      PERMITTED USE. Tenant shall use and occupy the Premises solely
                  for the purposes set forth in the SCHEDULE and for no other
                  purpose.

         (c)      COMPLIANCE WITH LAWS. Tenant shall not use or permit the use
                  of any part of the Premises for any purpose prohibited by law.
                  Tenant shall, at its sole expense, comply with and conform to
                  all of the requirements of all governmental authorities having
                  jurisdiction over the Building which relate in any way to the
                  condition, use and occupancy of the Premises throughout the
                  entire Term of this


                                     11
<PAGE>

                  Lease; provided, however, that the foregoing shall not be
                  interpreted to require Tenant to perform structural or capital
                  work unless required due to Tenant's specific use of the
                  Premises as opposed to office use in general. Without
                  limitation of the foregoing, Tenant covenants and agrees not
                  to bring into the Premises or to use, store, treat or dispose,
                  or permit the use, storage, treatment or disposal, in the
                  Premises of (i) any hazardous substance or regulated materials
                  as defined under any present or future federal, state or local
                  law, rule or regulation or (ii) any explosives or any
                  flammable substances, including, but not limited to, gasoline,
                  liquified petroleum gas, turpentine, kerosene and naphtha (the
                  substances and materials referred to in clauses (i) and (ii)
                  hereof are collectively referred to herein as "Hazardous
                  Materials"), except for such materials customarily used in
                  office operation (x) in such quantities which do not exceed
                  any legal limits, and (y) used, stored, treated and disposed
                  of in compliance with all applicable laws and regulations.

         (d)      ENVIRONMENTAL DISCLOSURE. Tenant, from time to time, upon not
                  less than ten (10) business days prior written request by
                  Landlord, will provide Landlord with such information in
                  Tenant's possession which Landlord may request regarding
                  Tenant's operations in the Premises (including, without
                  limitation, whether or not such operations involve the
                  generation, transportation, storage, treatment or disposal of
                  Hazardous Materials) and shall cooperate with Landlord in the
                  event Landlord is required to prepare an Environmental
                  Disclosure Document pursuant to the provisions of the Illinois
                  Responsible Property Transfer Act of 1988 or any government
                  rules or regulations issued pursuant thereto or in connection
                  therewith or in connection with any other federal, state or
                  local laws, rules or regulations.

5.       POSSESSION

         (a)      POSSESSION OF THE PREMISES. Possession of that portion of the
                  Third Floor Premises consisting of the 7,295 square feet of
                  Rentable Area identified on EXHIBIT A-1 hereto as the Phase 1
                  - 3rd Floor Space shall be tendered to Tenant by Landlord in
                  their "as-is" condition on April 1, 2000 and the remainder of
                  the Third Floor Premises identified on EXHIBIT A-1 as Phase 2
                  - 3rd Floor Space shall be tendered to Tenant by Landlord in
                  their "as-is" condition on July 2, 2000. Possession of the
                  Fourth Floor Premises shall be tendered to Tenant by Landlord
                  in their "as-is" condition on June 1, 2000. Possession of the
                  Phase 1 - 5th Floor Space shall be tendered to Tenant by
                  Landlord in their "as-is" condition on July 2, 2000 and
                  possession of the Phase 2 - 5th Floor Premises shall be
                  tendered to Tenant by Landlord in their "as-is" condition on
                  December 1, 2001. Possession of the Sixth Floor Premises shall
                  be tendered to Tenant by Landlord in their "as-is" condition
                  on April 1, 2000. Possession of the Seventh Floor Premises
                  shall be tendered to Tenant by Landlord in their "as-is"
                  condition on April 1, 2000. Possession of the Eighth Floor
                  Premises shall be tendered to Tenant by Landlord in their
                  "as-is" condition on October 1, 2000. Notwithstanding the
                  aforementioned references to "as-is" condition all portions of
                  the Premises when delivered by Landlord to Tenant shall be
                  broom clean with the electrical and mechanical systems to the
                  Premises in good working order. Following the tender of each
                  portion of the Premises Tenant shall thereafter perform its
                  obligations


                                     12
<PAGE>

                  relating to the construction of such portion of the Premises
                  as described in the Tenant Work Letter attached as EXHIBIT B
                  hereto and made a part hereof. Tenant's obligation to pay Rent
                  for such portion of the Premises as herein provided shall
                  commence on the Rent Commencement Date for such portion of the
                  Premises even in the event Tenant's Work (as defined in the
                  Tenant Work Letter) therein shall not be completed.
                  Notwithstanding the foregoing, Tenant's obligation to pay Rent
                  for such portion of the Premises shall be delayed one (1) day
                  for each day that the completion of the Tenant's Work in such
                  portion of the Premises is delayed as a result of Landlord's
                  failure to deliver vacant possession of such portion of the
                  Premises to Tenant on or before the date set forth above in
                  this SECTION 5(a) for the delivery of such portion of the
                  Premises to Tenant. Except as provided above, Landlord shall
                  have no other liability whatsoever on account of any such
                  delays and this Lease shall nevertheless continue in full
                  force and effect.

         (b)      The Tenant's taking possession of any portion of the Premises
                  shall be conclusive evidence that such portion of the Premises
                  was in good order and satisfactory condition when the Tenant
                  took possession. No promise of the Landlord to construct,
                  alter, remodel or improve the Premises or the Building and no
                  representation by Landlord or its agents respecting the
                  condition of the Premises or the Building have been made to
                  Tenant or relied upon by Tenant other than as may be contained
                  in this Lease.

         (c)      Under no circumstances shall the occurrence of any of the
                  events described in this SECTION 5 be deemed to accelerate or
                  defer the Termination Date.

         (d)      If Tenant takes possession or enters into occupancy of any
                  portion of the Premises for the purpose of conducting its
                  business therefrom prior to the date set forth in SECTION 5(a)
                  hereof for such portion of the Premises, such possession and
                  occupancy shall be pursuant to all of the terms, covenants and
                  conditions of this Lease, including the obligation to pay Base
                  Rent and Additional Rent (except as provided in SECTIONS 2(b)
                  AND 3(e) hereof).

6.       SERVICES

         (a)      LIST OF SERVICES. So long as Tenant is not in Default under
                  any covenant or condition of this Lease, Landlord shall
                  provide the following services on all days during the Term,
                  except Saturdays, Sundays and holidays, unless otherwise
                  stated:

                  (i)      Heating and air conditioning in the Premises from
                           Monday through Friday, from 8 a.m. to 6 p.m. and on
                           any Saturday which is not a holiday from 8 a.m. to 1
                           p.m. Landlord will operate the system of distribution
                           ducts, supply registers and diffusers, return grilles
                           and associated fixtures to provide in the Premises
                           [as partitioned in accordance with the Preliminary
                           Space Plans (as defined in the Tenant Work Letter)],
                           heating and air conditioning with capacity to provide
                           the following results during the business hours set
                           forth above; which heating and air conditioning
                           shall, within tolerances normal in first class office
                           buildings, be capable of


                                     13
<PAGE>

                           providing the following: (a) air conditioning which
                           shall be capable of maintaining inside space
                           conditions of seventy-eight degrees (78 DEG.)
                           Fahrenheit dry bulb and fifty percent (50%) relative
                           humidity when outside conditions are ninety-two
                           degrees (92 DEG.) Fahrenheit dry bulb and
                           seventy-five degrees (75 DEG.) Fahrenheit wet bulb
                           and (b) heating which shall be capable of maintaining
                           inside space conditions of not less than seventy-two
                           degrees (72 DEG.) Fahrenheit when outside air
                           temperatures are not less than minus ten degrees (-10
                           DEG.) Fahrenheit and not more than sixty-five degrees
                           (65 DEG.) Fahrenheit. The foregoing is based upon
                           occupancy density of not more than one (1) person per
                           hundred (100) square feet of floor area, and a
                           maximum electric lighting and office machine load of
                           five (5) watts per square foot of floor area.

                           Tenant will pay for all heating and air conditioning
                           requested and furnished prior to or following such
                           hours at rates to be established from time to time by
                           Landlord. Landlord's obligations with respect to
                           heating and air conditioning are subject to all
                           governmental rules, regulations and guidelines
                           applicable thereto. Wherever heat generating machines
                           or equipment are used by Tenant in the Premises,
                           which affect the temperature otherwise maintained by
                           the air-cooling system, or where the configuration
                           and placement of such equipment creates a per square
                           foot heat load above what would be considered normal
                           for office use, Landlord reserves the right to
                           install supplementary air-conditioning units in the
                           Premises and the expense of installation, operation
                           and maintenance of any such supplementary units shall
                           be paid by Tenant to Landlord as Additional Rent.

                  (ii)     Electricity solely for the lighting fixtures in the
                           Premises of up to two (2) watts per square foot of
                           rentable area within the Premises, together with
                           adequate electrical wiring and facilities to the
                           Premises for standard building lighting fixtures and
                           for Tenant's incidental uses. Distribution within the
                           Premises is at Tenant's expense, although Tenant may
                           use any existing conduit system within the Premises.
                           All electricity used in the Premises other than for
                           lighting fixtures shall be separately metered by a
                           meter or meters to be installed at Landlord's
                           expense. Tenant agrees to pay for such electricity
                           directly to the utility providing such electricity.
                           Tenant shall bear the cost of providing all light
                           fixtures and replacement of all lamps, tubes,
                           ballasts and starters for lighting fixtures. With
                           respect to such incidental uses, adequate electrical
                           wiring and facilities will be furnished up to the
                           meter in the Premises by Landlord, provided that: (a)
                           the connected electrical load of the incidental use
                           equipment does not exceed an average of two (2) watts
                           per square foot of rentable area within the Premises;
                           (b) the electricity for incidental uses will be at a
                           nominal one hundred twenty (120) volts and no
                           electrical circuit for the supply of such incidental
                           use will have a current capacity exceeding twenty
                           (20) amperes with a load not exceeding sixteen (16)
                           amperes; and (c) such electricity will be used only
                           for equipment and accessories normal to office usage.
                           If Tenant's requirements for electricity for
                           incidental uses exceed those set


                                     14
<PAGE>

                           forth in the preceding sentence, Landlord reserves
                           the right to require Tenant to install the conduit,
                           wiring and other equipment necessary to supply
                           electricity for such excess incidental use
                           requirements at Tenant's expense by arrangement with
                           Commonwealth Edison Company or another approved local
                           utility. If Tenant's actual usage of electricity for
                           lighting exceeds two (2) watts per square foot, then
                           Landlord may charge and collect from Tenant a fee for
                           such excess usage, the amount of such fee to be
                           determined by Landlord. With respect to electricity
                           for lighting, electricity for two hundred sixty (260)
                           hours of lighting per month will be provided by
                           Landlord as part of Operating Expenses. Tenant shall
                           be billed monthly for all overtime hours of lighting
                           in excess of two hundred sixty (260) hours per month.

                           With regard to the Seventh Floor Premises only,
                           Landlord shall make available to the seventh floor
                           electrical room 400 amps, 480 volt three phase (one
                           feed) electrical power. It shall be Tenant's
                           responsibility and cost to distribute such power from
                           the electrical room to and throughout the Seventh
                           Floor Premises. Landlord will work with the local
                           utility company to make available to Tenant a second
                           feed for such electrical power to the Seventh Floor
                           Premises. The installation of such second feed (if
                           available) to the seventh floor and thereafter to the
                           Seventh Floor Premises shall be entirely at Tenant's
                           cost and expense. In addition, Tenant shall pay all
                           of Landlord's out-of-pocket costs in connection with
                           obtaining such second feed.

                  (iii)    City water from the regular Building outlets for
                           drinking, lavatory and toilet purposes. Upon
                           execution by Landlord and Tenant of the "Condenser
                           Water Addendum" attached hereto as EXHIBIT E,
                           Landlord agrees to make available to Tenant
                           supplemental condenser water as therein provided. If
                           Landlord and Tenant have not executed the Condenser
                           Water Addendum, then Landlord shall not have any
                           obligation to provide Tenant with supplemental
                           condenser water.

                  (iv)     Janitorial services as generally provided in
                           first-class office buildings in downtown Chicago.

                  (v)      Window washing of the inside and outside of those
                           windows in the Building's perimeter walls which are
                           situated in the Premises, weather permitting, at
                           intervals to be determined by Landlord, but in no
                           event less than two (2) times per Calendar Year with
                           respect to the inside of said windows and no less
                           than three (3) times per calendar year with respect
                           to the outside of said windows.

                  (vi)     Adequate automatic passenger elevator service.

                  (vii)    Freight elevator services, Monday through Friday
                           only, from 7 a.m. to 5 p.m. from the first lower
                           level of the Building to the level on which the
                           Premises are located, subject to reasonable
                           scheduling by Landlord. The


                                     15
<PAGE>

                           use of freight elevators shall be subject to
                           reasonable regulations promulgated by Landlord from
                           time to time.

                  (viii)   Receiving room and loading dock services, on any
                           Monday through Friday which is not a Holiday, from 7
                           a.m. to 4 p.m., subject to reasonable scheduling by
                           Landlord. The use of the receiving room and loading
                           dock shall be subject to reasonable regulations
                           promulgated by Landlord from time to time.

         (b)      INTERRUPTION OF SERVICES. Except for the limited abatement of
                  Rent upon a fire or casualty described in SECTION 11, Tenant
                  agrees that Landlord shall not be liable in damages, by
                  abatement of Rent or otherwise, for failure to furnish or
                  delay in furnishing any service, or for any diminution in the
                  quality or quantity thereof, when such failure or delay or
                  diminution is occasioned, in whole or in part, by repairs,
                  replacements, or improvements, by any strike, lockout or other
                  labor trouble, by inability to secure electricity, gas or
                  other fuel, or water, at the Building after reasonable effort
                  so to do, by any accident or casualty whatsoever, by act or
                  default of Tenant or other parties, or by any cause beyond
                  Landlord's reasonable control. Except in cases of emergency,
                  Landlord shall give Tenant reasonable prior notice of any
                  delay or diminution in any service and shall use reasonable
                  efforts to minimize any inconvenience to Tenant where such
                  delay or diminution is the result of Landlord's voluntary
                  actions. Such failures or delays or diminution shall never be
                  deemed to constitute an eviction or disturbance of Tenant's
                  use and possession of the Premises or relieve Tenant from
                  paying Rent or performing any of its obligations under this
                  Lease; provided, however, that if any such service is
                  interrupted or diminished, and if (i) such interruption or
                  diminution does not arise as a result of an act or omission of
                  Tenant, (ii) such interruption or diminution does not arise as
                  a result of a matter or condition affecting two or more city
                  blocks, such as a city-wide power outage, (iii) as a result of
                  such interruption or diminution, the Premises or any material
                  portion thereof is rendered untenantable (meaning a lack of
                  elevator access or Tenant's inability to reasonably use the
                  Premises or such material portion thereof in the normal course
                  of its business) and Tenant in fact so ceases to use the
                  Premises or such material portion thereof for the normal
                  conduct of its business, and (iv) such interruption or
                  diminution continues for a period of three (3) or more
                  consecutive business days, then the Rent payable hereunder
                  shall be equitably abated according to the percentage of the
                  space in the Premises so rendered untenantable and not being
                  used by Tenant. The foregoing abatement of Rent shall become
                  effective as of the day the Premises or such material portion
                  thereof becomes untenantable and Tenant ceases to use such
                  space for the normal conduct of its business.

         (c)      CHARGES FOR SERVICES. Charges for any service for which Tenant
                  is required to pay, from time to time hereunder, including but
                  not limited to hoisting services or after hours heating or air
                  conditioning shall be due and payable at the same time as the
                  installment of Rent with which they are billed, or if billed
                  separately, shall be due and payable within twenty (20) days
                  after such billing. If Tenant shall fail to make payment for
                  any such services within five (5) days following Landlord's


                                     16
<PAGE>

                  written demand therefor (which demand shall be in addition to
                  the original billing therefor), Landlord may, without further
                  notice to Tenant, discontinue any or all of such additional
                  services until Tenant pays all amounts due, and such
                  discontinuance shall not be deemed to constitute an eviction
                  or disturbance of Tenant's use and possession of the Premises
                  or relieve Tenant from paying Rent or performing any of its
                  other obligations under this Lease.

         (d)      ENERGY/NATURAL RESOURCES CONSERVATION. Notwithstanding
                  anything to the contrary in this SECTION 6 or elsewhere in
                  this Lease, Landlord shall have the right to institute such
                  policies, programs and measures as may be reasonably necessary
                  for the conservation, recycling and/or preservation of energy
                  and natural resources or energy or natural resource related
                  services, or as may be required to comply with any applicable
                  codes, rules and regulations, whether mandatory or voluntary.

         (e)      BILLING FOR ELECTRICITY.

                  (i)      SEPARATE METERING. Tenant shall pay for the use of
                           the electrical service to the Premises for incidental
                           uses as described above directly to the utility
                           company supplying electricity to the Premises based
                           upon separate metering and billing. Tenant shall be
                           billed directly by such utility company and Tenant
                           agrees to pay each bill promptly in accordance with
                           its terms. If for any reason, Tenant cannot be billed
                           directly, Landlord shall forward to Tenant each bill
                           received by it with respect to such electrical usage
                           in the Premises and Tenant shall pay it promptly in
                           accordance with its terms.

                  (ii)     LACK OF SEPARATE METERING. If Tenant's incidental
                           uses of electricity in the Premises cannot be
                           separately metered for any reason, Tenant shall pay
                           Landlord as Additional Rent, in monthly installments
                           at the time prescribed for monthly installments of
                           Rent, an amount, as estimated by Landlord from time
                           to time (which estimate shall be based on a survey
                           reasonably acceptable to Tenant), which Tenant would
                           pay for such electricity if the same were separately
                           metered to the Premises by the local electric utility
                           company and billed to Tenant at such utility
                           company's then current rates.

7.       REPAIRS

         (a)      Landlord shall, as part of Operating Expenses, keep the common
                  areas of the Building (including, without limitation, all
                  concourses, pedestrian passageways, elevator lobbies and
                  restrooms), the roof, structural elements of the Building and
                  those portions of the mechanical, electrical, plumbing, HVAC
                  and other systems serving both the Premises and other areas of
                  the Building in good order, repair and condition, including
                  replacement or repair of all damaged or broken fixtures and
                  appurtenances, at all times during the Term.

         (b)      Except as provided in Paragraph 7(a) above, Tenant will, at
                  Tenant's own expense, keep the Premises in good order, repair
                  and condition at all times during


                                      17
<PAGE>

                  the Term, subject to reasonable wear and tear, fire, casualty
                  and condemnation excepted, and Tenant shall promptly and
                  adequately repair all damage to the Premises and replace or
                  repair all damaged or broken fixtures and appurtenances
                  included in the Premises, under the supervision and subject to
                  the approval of the Landlord, and within any reasonable period
                  of time specified by the Landlord. If Tenant does not do so,
                  Landlord may, but need not, make such repairs and
                  replacements, and Tenant shall pay Landlord the reasonable
                  cost thereof plus a coordination fee payable to Landlord in
                  connection with each such repair and/or replacement equal to
                  three percent (3%) of the actual total cost of any such repair
                  or replacement, plus the cost of trash removal. Tenant shall
                  pay such costs and fee within twenty (20) days after being
                  billed therefor. Landlord may, but shall not be required to,
                  enter the Premises at all reasonable times to make such
                  repairs, alterations, improvements, installations and
                  additions to the Premises or to the Building or to any
                  equipment located in the Building as Landlord shall desire or
                  deem necessary or as Landlord may be required to do by
                  governmental authority or court order or decree; provided,
                  however, that Landlord shall use commercially reasonable
                  efforts not to interfere with Tenant's operation of its
                  business.

8.       ADDITIONS AND ALTERATIONS

         (a)      Except with respect to (i) the Work described in the Tenant
                  Work Letter and (ii) minor painting, the moving of furniture
                  or the hanging of wall coverings or artwork, Tenant shall not,
                  without the prior written consent of Landlord, make any
                  alterations, improvements, installations or additions to the
                  Premises, which shall include, without limitation, installing
                  telephone, computer or internal sound or paging systems or
                  other similar systems or performing any decorating, painting
                  or other similar work in the Premises. Landlord's consent
                  shall not be unreasonably withheld or delayed so long as such
                  alterations, improvements, installations and additions are
                  consistent with the permitted uses of the Premises set forth
                  in the SCHEDULE hereof and do not adversely affect the
                  mechanical, electrical, plumbing, HVAC or structural
                  components or common systems of the Building. If Landlord
                  consents to any alterations, improvements, installations or
                  additions, it may impose such reasonable conditions with
                  respect thereto as Landlord deems appropriate, including,
                  without limitation, requiring Tenant to furnish Landlord with
                  security for the payment of all costs to be incurred in
                  connection with such work, insurance against liabilities which
                  may arise out of such work, plans and specifications plus
                  permits necessary for such work and, following completion,
                  "as-built" drawings showing the actual location of the
                  alterations, improvements, installations and additions. The
                  work necessary to make any alterations, improvements,
                  installations or additions to the Premises, whether prior to
                  or subsequent to the Commencement Date shall be done at
                  Tenant's expense by contractors selected from a list of
                  contractors preapproved by Landlord. Tenant shall promptly pay
                  to Landlord or the Tenant's contractors, as the case may be,
                  when due, the cost of all such work plus, in all cases other
                  than decorating or redecorating, a coordination fee payable to
                  Landlord in connection with each such improvement,
                  installation, alteration and/or addition equal to three
                  percent (3%) of the actual total cost of any such improvement,
                  installation,


                                      18
<PAGE>

                  alteration or addition, plus the cost of trash removal. Tenant
                  shall pay such costs and fee within twenty (20) days after
                  being billed therefor.

         (b)      All alterations, improvements, installations and additions to
                  the Premises, whether temporary or permanent in character,
                  made or paid for by Landlord or Tenant, shall without
                  compensation to Tenant become Landlord's property at the
                  termination of this Lease by lapse of time or otherwise and
                  shall, unless Landlord is entitled to and does request their
                  removal (in which case Tenant shall remove the same as
                  provided in SECTION 16), be relinquished to Landlord in good
                  condition, ordinary wear and damage resulting from fire or
                  other casualty and condemnation excepted.

9.       COVENANT AGAINST LIENS

         Tenant has no authority or power to cause or permit any lien or
         encumbrance of any kind whatsoever, whether created by act of Tenant,
         operation of law or otherwise, to attach to or be placed upon
         Landlord's title or interest in the Land, Building or Premises, and any
         and all liens and encumbrances created by Tenant shall attach to
         Tenant's interest only. Tenant covenants and agrees not to suffer or
         permit any lien of mechanics or materialmen or others to be placed
         against the Land, Building or Premises or any improvement in the
         Premises (whether installed or paid for by Landlord or Tenant) with
         respect to work or services claimed to have been performed for or
         materials claimed to have been furnished to Tenant or the Premises and,
         if any such lien attaches or a claim for a lien is asserted, Tenant
         covenants and agrees to cause it to be promptly released and removed of
         record; provided, however, that if such lien is being contested in good
         faith by Tenant by appropriate proceedings diligently pursued, Tenant
         shall not be in default hereunder if Tenant shall, in a manner subject
         to Landlord's prior written reasonable approval, cause such lien or
         claim of lien to be bonded or insured over by a title insurance company
         selected by Landlord (which title insurance shall, in any event, inure
         to the benefit of Landlord, Landlord's mortgagees and any potential
         purchasers of the Land or Building of which Tenant shall be notified),
         and provided that, in any event, such lien or claim of lien shall be
         released or removed within four (4) months of the date such lien first
         attached. If such lien is not promptly released and removed or bonded
         or insured over as aforesaid, Landlord, at its sole option, may take
         all action necessary to release and remove such lien (without any duty
         to investigate the validity thereof) and Tenant shall promptly upon
         notice reimburse Landlord for all sums, costs and expenses (including
         reasonable attorney's fees) incurred by Landlord in connection with
         such lien.

         Notwithstanding anything in this Lease to the contrary, Tenant
         covenants and agrees not to suffer or permit any equipment lien to
         attach to any of the fixtures or improvements in the Premises, whether
         installed and/or paid for by Landlord or Tenant.

10.      INSURANCE

         (a)      WAIVER OF SUBROGATION. Landlord and Tenant each hereby waive
                  any and every claim for recovery from the other for any and
                  all loss of or damage to the Building or Premises or to the
                  contents thereof, which loss or damage is covered by valid and
                  collectible physical damage insurance policies. Landlord
                  waives any and every claim against Tenant for any and all loss
                  of or damage to the Building or the


                                      19
<PAGE>

                  Premises or the contents thereof which would have been covered
                  had the insurance policies required to be maintained by
                  Landlord by this Lease been in force, to the extent that such
                  loss or damage would have been recoverable under such
                  insurance policies. Tenant waives any and every claim against
                  Landlord for any and all loss of or damage to the Building or
                  the Premises or the contents thereof which would have been
                  covered had the insurance policies required to be maintained
                  by Tenant by this Lease been in force, to the extent that such
                  loss or damage would have been recoverable under such
                  insurance policies. Inasmuch as this mutual waiver will
                  preclude the assignment of any such claim by subrogation (or
                  otherwise) to an insurance company (or any other person),
                  Landlord and Tenant each agree to give to each insurance
                  company which has issued, or in the future may issue, to it
                  policies of physical damage insurance, written notice of the
                  terms of this mutual waiver, and to have said insurance
                  policies properly endorsed, if necessary, to prevent the
                  invalidation of said insurance coverage by reason of said
                  waiver.

         (b)      COVERAGE. Tenant shall purchase and maintain insurance during
                  the entire Term for the benefit of Tenant and Landlord (as
                  their interest may appear) with terms, coverages and in
                  companies reasonably satisfactory to Landlord, and with such
                  increases in limits as Landlord may from time to time
                  reasonably request, but initially Tenant shall maintain the
                  following coverages in the following amounts:

                  (i)      Commercial General Liability Insurance naming
                           Landlord, Landlord's management, leasing and
                           development agents and any mortgagees designated by
                           Landlord as additional insureds, with coverage for
                           premises/operations, personal and advertising injury,
                           products/completed operations and contractual
                           liability with combined single limits of liability of
                           not less than $5,000,000 for bodily injury and
                           property damage per occurrence. If Tenant desires to
                           serve liquor in the Premises, host liquor insurance,
                           naming Landlord, Landlord's management, leasing and
                           development agents and any mortgagees designated by
                           Landlord as additional insureds covering any
                           liability that might arise from the provision or use
                           of alcoholic beverages by Tenant on the Premises in
                           an amount reasonably satisfactory to Landlord from
                           time to time in light of statutory limits.

                  (ii)     Property Insurance covering the Work and all other
                           Tenant improvements in the Premises, office
                           furniture, trade fixtures, office equipment,
                           merchandise and all other items of Tenant's property
                           on the Premises, which insurance shall, with respect
                           only to the Work and other Tenant improvements, name
                           Landlord, and any mortgagees designated by Landlord
                           as additional loss payees as their interests may
                           appear. Such insurance shall be written on an "all
                           risks" of physical loss or damage basis including but
                           not limited to the perils of fire, extended coverage,
                           windstorm, vandalism, malicious mischief, sprinkler
                           leakage, flood and earthquake, for the full
                           replacement cost value of the covered items and in
                           amounts that meet any co-insurance clause of the
                           policies of insurance with a deductible amount not to
                           exceed $10,000.


                                      20
<PAGE>

                  (iii)    Workers' Compensation Insurance with statutory
                           benefits and Employers Liability Insurance with the
                           following amounts: Each Accident - $500,000; Disease
                           - Policy Limit - $500,000; Disease - Each Employee -
                           $500,000.

                  Tenant shall, prior to the commencement of the Term and on
                  each anniversary of the Commencement Date, furnish to Landlord
                  certificates evidencing such coverage, which certificates
                  shall state that such insurance coverage may not be changed or
                  cancelled without at least thirty (30) days prior written
                  notice to Landlord and Tenant. The insurance maintained by
                  Tenant shall be deemed to be primary insurance and any
                  insurance maintained by Landlord shall be deemed secondary
                  thereto.

                  Notwithstanding anything herein to the contrary, provided
                  Landlord approves Tenant's blanket policy (which approval
                  shall not be unreasonably withheld) Tenant shall have the
                  right to maintain the required liability insurance in the form
                  of a blanket policy covering other locations of Tenant in
                  addition to the Premises; Tenant shall provide Landlord with a
                  certificate of insurance specifically naming the location of
                  the Premises and naming Landlord as required by this
                  subsection.

         (c)      AVOID ACTION INCREASING RATES. Tenant shall comply with all
                  applicable laws and ordinances, all orders and decrees of
                  court and all requirements of other governmental authorities,
                  and shall not, directly or indirectly, make any use of the
                  Premises which may thereby be prohibited or be dangerous to
                  person or property or which may jeopardize any insurance
                  coverage or may increase the cost of insurance or require
                  additional insurance coverage. If Tenant fails to comply with
                  the provisions of this SECTION 10(c) and: (i) any insurance
                  coverage is jeopardized and Tenant fails to correct such
                  dangerous or prohibited use following notice within the
                  applicable cure period set forth in SECTION 22 hereof; or (ii)
                  insurance premiums are increased and Tenant fails, following
                  notice, to cease such use within the applicable cure period
                  set forth in SECTION 22 hereof, then in each event such
                  failure shall constitute a Default by Tenant hereunder and
                  Landlord shall have all of its remedies as set forth in this
                  Lease.

         (d)      INSURANCE MAINTAINED BY LANDLORD. Landlord agrees to maintain
                  property insurance written on an "all-risks" of physical loss
                  or damage basis insuring the Building for the full replacement
                  cost thereof (excluding the cost of excavations, foundations
                  and footings below the lowest basement floor).

11.      FIRE OR CASUALTY

         (a)      SECTION 7 hereof notwithstanding, if the Premises or the
                  Building (including machinery or equipment used in its
                  operation) shall be damaged by fire or other casualty and if
                  such damage does not cause a termination of this Lease as
                  described in the following sentences, then Landlord shall
                  repair and restore the damage with reasonable promptness,
                  subject to reasonable delays for insurance adjustments and
                  delays caused by matters beyond Landlord's reasonable control,
                  but Landlord shall not be obligated to expend for repairing or
                  restoring the damage an amount in excess of the proceeds of
                  insurance recovered with respect


                                      21
<PAGE>

                  to the damage. If in Landlord's estimate the Premises cannot
                  be restored within three hundred sixty-five (365) days from
                  the date of such fire or casualty, then Landlord shall give
                  notice to Tenant of such estimate within one hundred twenty
                  (120) days after such fire or casualty. Tenant may elect in
                  writing within sixty (60) days following the date of such
                  notice from Landlord to terminate this Lease effective as of
                  the date of Tenant's notice. If any such damage: (i) renders
                  three (3) or more floors of the Building untenantable; or (ii)
                  renders general Building systems inoperable and such systems
                  cannot be repaired in Landlord's reasonable estimate within
                  three hundred sixty-five (365) days from the date of such
                  damage, or (iii) occurs within the last two (2) Lease Years,
                  Landlord shall have the right to terminate this Lease as of
                  the date of such damage upon giving written notice to the
                  Tenant at any time within one hundred twenty (120) days after
                  the date of such damage. Landlord shall have no liability to
                  Tenant, and Tenant shall not be entitled to terminate this
                  Lease, by virtue of any delays in completion of such repairs
                  and restoration. Rent, however, shall abate on those portions
                  of the Premises as are, from time to time, untenantable as a
                  result of such damage.

         (b)      Notwithstanding anything to the contrary herein set forth,
                  Landlord shall have no duty pursuant to this SECTION 11 to
                  repair or restore any portion of the Work or any other
                  alterations, additions, installations or improvements in the
                  Premises or the decorations thereto except to the extent that
                  the proceeds of the insurance carried by Tenant are timely
                  received by Landlord. In the event Landlord does so timely
                  receive the proceeds of the insurance carried by Tenant,
                  Landlord shall work with Tenant to repair or restore the Work
                  or such other alterations, additions, installations or
                  improvements, but shall not be required to expend any of its
                  own funds in connection therewith. Such work shall be
                  performed in accordance with the provisions of SECTION 8
                  hereof. If Tenant desires any other or additional repairs or
                  restoration, and if Landlord consents thereto, it shall be
                  done at Tenant's sole cost and expense subject to all of the
                  provisions of SECTIONS 7 and 8 hereof. Tenant acknowledges
                  that Landlord shall be entitled to the full proceeds of any
                  insurance coverage, whether carried by Landlord or Tenant, for
                  damage to Tenant's Work or any other alterations, additions,
                  installations, improvements or decorations which would become
                  Landlord's property upon the termination of this Lease.

12.      WAIVER OF CLAIMS - INDEMNIFICATION

         To the extent not prohibited by law and subject to the waiver of
         subrogation contained in SECTION 10(a), Landlord and its partners,
         affiliates, officers, agents, servants and employees shall not be
         liable for any damage either to person, property or business or
         resulting from the loss of use thereof sustained by Tenant or by other
         persons due to the Building or any part thereof or any appurtenances
         thereto becoming out of repair, or due to the happening of any accident
         or event in or about the Building, including the Premises, or due to
         any act or neglect of any tenant or occupant of the Building or of any
         other person, unless caused by the negligence or willful misconduct of
         Landlord or its agents, employees or contractors. This provision shall
         apply particularly, but not exclusively, to damage caused by gas,
         electricity, snow, ice, frost, steam, sewage, sewer gas or odors, fire,
         water or by the bursting or leaking of pipes, faucets, sprinklers,


                                     22
<PAGE>

         plumbing fixtures and windows, and, except as provided above, shall
         apply without distinction as to the person whose act or neglect was
         responsible for the damage and shall apply whether the damage was due
         to any of the causes specifically enumerated above or to some other
         cause of an entirely different kind. Tenant further agrees that all
         personal property upon the Premises, or upon loading docks, receiving
         and holding areas, or freight elevators of the Building, shall be at
         the risk of Tenant only, and that Landlord shall not be liable for any
         loss or damage thereto or theft thereof. Without limiting any other
         provisions hereof, but subject to the provisions of SECTION 10(a)
         hereof, except for liability caused by the negligence or willful acts
         of Landlord or its agents, employees or contractors, Tenant agrees to
         defend, protect, indemnify and save harmless Landlord and its partners,
         affiliates, officers, agents, servants and employees from and against
         all liability to third parties arising out of the use of the Premises
         or the acts or omissions of Tenant or its servants, agents, employees,
         contractors, suppliers or workers.

         Except for liability caused by the negligence or willful acts or
         omissions of Tenant or Tenant's partners, affiliates, officers, agents,
         servants or employees and subject to SECTION 10(a) hereof, Landlord
         agrees to defend, protect, indemnify and save harmless Tenant and its
         partners, shareholders, directors, affiliates, officers, agents,
         servants, contractors and employees from and against all liability to
         third parties arising out of negligent acts or omissions of Landlord or
         its servants, agents, employees, contractors, suppliers or workers.

         The provisions of this SECTION 12 shall survive the expiration of the
         Term or earlier termination of this Lease or the termination of
         Tenant's right to possession of the Premises.

13.      NONWAIVER

         No waiver of any provision of this Lease shall be implied by any
         failure of either Landlord or Tenant to enforce any remedy on account
         of the violation of such provisions, even if such violation is
         continued or repeated subsequently, and no express waiver shall affect
         any provision other than the one specified in such waiver and that one
         only for the time and in the manner specifically stated. No receipt of
         monies by Landlord from Tenant after the termination of this Lease
         shall in any way alter the length of the Term or of Tenant's right of
         possession hereunder or after the giving of any notice shall reinstate,
         continue or extend the Term or affect any notice given Tenant prior to
         the receipt of such monies, it being agreed that after the service of
         notice or the commencement of a suit or after final judgment for
         possession of the Premises, Landlord may receive and collect any Rent
         due, and the payment of said Rent shall not waive or affect said
         notice, suit or judgment.

14.      CONDEMNATION

         If the Land or the Building (or any portion of the Building, the loss
         of which would require reconfiguration or restoration of the Building
         which Landlord reasonably estimates will cost in excess of $2,500,000)
         shall be taken or condemned by any competent authority for any public
         or quasi-public use or purpose, Landlord shall have the right,
         exercisable at its sole discretion, to cancel this Lease upon not less
         than sixty (60) days notice prior to the date of cancellation
         designated in the notice. No money or

                                 23
<PAGE>

         other consideration shall be payable by Landlord to Tenant for the
         right of cancellation and Tenant shall have no right to share in the
         condemnation award or in any judgment for damages caused by such taking
         or condemnation. Notwithstanding the foregoing, Tenant may pursue a
         separate award to recover the cost of Tenant's moving expenses and
         improvements to the Premises paid for by Tenant and the loss of any
         trade fixtures or personal property, provided that such separate award
         shall not reduce the award or judgment recoverable by Landlord.

15.      ASSIGNMENT AND SUBLETTING

         (a)      Subject to any provisions of this SECTION 15 to the contrary,
                  Tenant shall not, without the prior written consent of
                  Landlord, which consent shall not be unreasonably withheld or
                  delayed, (i) assign, convey or mortgage this Lease or any
                  interest hereunder; (ii) permit to occur or permit to exist
                  any assignment of this Lease, or any lien upon Tenant's
                  interest, voluntarily or by operation of law; (iii) sublet the
                  Premises or any part thereof; (iv) advertise as available for
                  sublet or assignment all or any portion of the Premises,
                  except that Tenant may advertise to the brokerage community so
                  long as such advertising is in keeping with a standard of
                  professionalism and Landlord is given advance notice and
                  copies of such advertisements; or (v) permit the use of the
                  Premises by any parties other than Tenant and its employees.
                  Any such action on the part of Tenant shall be void and of no
                  effect. There shall be no partial assignment of Tenant's
                  interest in this Lease. Notwithstanding anything contained
                  herein to the contrary, Landlord shall not be deemed to have
                  acted unreasonably in its election not to consent to any such
                  action on the part of Tenant because (aa) a Default shall have
                  occurred and be continuing under this Lease or Tenant shall
                  otherwise be in default in the performance of the terms,
                  covenants or conditions contained in this Lease, (bb) the
                  proposed assignee or sublessee (the "Proposed Tenant") shall
                  be an existing tenant or occupant of the Building, (cc) such
                  assignment or subletting shall cause Landlord to be in breach
                  of any "exclusive use" or similar provision contained in any
                  other lease for space in the Building (provided that such
                  provision shall not be in conflict with the use provision set
                  forth in the SCHEDULE), (dd) in the reasonable judgment of
                  Landlord, the Proposed Tenant is of a character or is engaged
                  in a business which would be deleterious to the reputation of
                  the Building, or the Proposed Tenant is not sufficiently
                  financially responsible to perform its obligations under any
                  such assignment or sublease, (ee) the portion of the Premises
                  which Tenant proposes to sublease including the means of
                  ingress and egress thereto and the proposed use thereof, and
                  the remaining portion of the Premises will violate any city,
                  state or federal law, ordinance or regulation; (ff) the
                  Proposed Tenant is a government agency (or any subdivision
                  thereof); (gg) the Proposed Tenant is a party with whom
                  Landlord is then actively negotiating a lease for space in the
                  Building, provided, however, that the foregoing are merely
                  examples of the reasons for which Landlord may reasonably not
                  consent to any such actions by Tenant and shall not be deemed
                  exclusive of any reason for reasonably making such election,
                  whether similar or dissimilar to the foregoing examples. The
                  term "sublease" and all words derived therefrom, as used in
                  this SECTION 15 shall include any subsequent sublease or
                  assignment of such sublease and any other interest arising
                  under such sublease. Landlord's consent to any

                                    24
<PAGE>

                  assignment, subletting or transfer or Landlord's election to
                  accept any assignee, subtenant or transferee as the Tenant
                  hereunder and to collect rent from such assignee, subtenant or
                  transferee shall not release Tenant or any subsequent Tenant
                  from any covenant or obligation under this Lease, and Tenant
                  further expressly acknowledges and agrees that any renewal
                  rights, expansion rights, reduction rights, rights of first
                  offer, termination rights or limitations on Taxes or Operating
                  Expenses shall be deemed personal to the original Tenant and
                  shall not inure to the benefit of any assignee (other than a
                  Permitted Assignee), subtenant or transferee taking from the
                  original Tenant. Landlord's consent to any assignment,
                  subletting or transfer shall not constitute a waiver of
                  Landlord's right to withhold its consent to any future
                  assignment, subletting, or transfer. Landlord may condition
                  its consent upon execution by the subtenant or assignee of an
                  instrument confirming such restrictions on further subleasing
                  or assignment and joining in the waivers and indemnities made
                  by Tenant hereunder insofar as such waivers and indemnities
                  relate to the affected space. Without limiting the foregoing,
                  Tenant agrees to indemnify, defend and hold Landlord and its
                  employees, agents, their officers and partners harmless from
                  and against any claims made by any broker or finder for a
                  commission or fee in connection with any subleasing or
                  assignment by Tenant or any subtenant or assignee of Tenant.

         (b)      If Tenant desires the consent of Landlord to an assignment or
                  subletting, Tenant shall submit to Landlord, at least thirty
                  (30) days prior to the proposed effective date of the
                  assignment or sublease, a written notice which includes:

                  (i)      All documentation then available related to the
                           proposed sublease or assignment (copies of the final
                           executed documentation are to be supplied to Landlord
                           by Tenant as soon as possible, but in any event at
                           least ten (10) business days prior to the effective
                           date of such assignment or sublease); and

                  (ii)     Reasonably sufficient information to permit Landlord
                           to determine the identity and character of the
                           proposed subtenant or assignee and the financial
                           condition of the proposed assignee or subtenant.

                           Landlord agrees to notify Tenant as to whether
                  Landlord consents to such assignment or sublease within thirty
                  (30) days after receipt by Landlord of all documents required
                  pursuant to (i) and (ii) above including final executed
                  documentation. If the terms of the proposed sublease or
                  assignment change in any material respect from the terms
                  contained in the documents delivered to Landlord pursuant to
                  (i) or (ii) above, or the identity of the sublessee or
                  assignee changes then Tenant shall resubmit such documents to
                  Landlord and indicate in writing such changes and Landlord
                  shall have an additional ten (10) business days after receipt
                  of such revised documents to either approve or disapprove of
                  such assignment or sublease.

         (c)      In addition to withholding its consent Landlord shall have the
                  right to terminate this Lease in the event of a proposed
                  assignment of this Lease or a proposed sublease of the entire
                  Premises or to terminate this Lease as to that portion of the

                                       25
<PAGE>

                  Premises which Tenant seeks to sublet, if Tenant seeks to
                  sublease less than the entire Premises. Landlord may exercise
                  such right to terminate by giving written notice to Tenant at
                  any time on or before the date by which Landlord is required
                  to consent or object to such assignment or sublease. If
                  Landlord exercises its right to terminate, the Lease or
                  portion thereof shall be deemed terminated effective as of,
                  Landlord shall be entitled to recover possession of and Tenant
                  shall surrender such portion of the Premises on the later of:
                  (i) the proposed date for possession by such assignee or
                  subtenant, or (ii) ninety (90) days after the date of
                  Landlord's notice of termination to Tenant.

         (d)      If Landlord consents to any assignment of this Lease or a
                  sublease of the Premises, as a condition of Landlord's
                  consent, Tenant shall pay to Landlord any reasonable
                  attorneys' fees and expenses incurred by Landlord in
                  connection with such assignment or sublease plus fifty percent
                  (50%) of all Sublease Profits (as defined below) derived by
                  Tenant from such assignment or sublease. "Sublease Profits"
                  shall mean the entire excess (after deducting all reasonable
                  costs of subletting, including, without limitation, brokerage
                  commissions, rent concessions and improvement allowances) of
                  revenues generated by the assignment of this Lease or the
                  subleasing of the Premises over the Rent applicable thereto.
                  All such revenues shall be applied first to reimbursement of
                  such costs of subletting or assigning until they are paid in
                  full. Tenant shall furnish Landlord with a sworn statement,
                  certified by an officer of Tenant, setting forth in detail the
                  computation of Sublease Profits, and Landlord, or its
                  representatives, shall have access to the books, records and
                  papers of Tenant in relation thereto, and to make copies
                  thereof. If a part of the consideration for such assignment
                  shall be payable other than in cash, the payment to Landlord
                  shall be payable in accordance with the foregoing percentage
                  of the cash and other non-cash considerations in such form as
                  is reasonably satisfactory to Landlord. Such percentage of
                  Sublease Profits shall be paid to Landlord promptly by Tenant
                  upon Tenant's receipt from time to time of periodic payments
                  from such assignee or subtenant or at such other time as
                  Tenant shall realize Sublease Profits from such assignment or
                  sublease. If such sublease or assignment is part of a larger
                  transaction in which other assets of Tenant are being
                  transferred, the consideration for the assignment or sublease
                  shall be the amount by which the fair market value of the
                  Premises exceeds the value of the Rent to be paid by Tenant
                  hereunder.

         (e)      Subject to the provisions of SECTION 15(f) hereof, if Tenant
                  is a partnership, a withdrawal or change, whether voluntary,
                  involuntary or by operation of law or in one or more
                  transactions, of partners owning directly or indirectly a
                  controlling interest in Tenant shall be deemed an assignment
                  of this Lease and subject to the provisions of this SECTION
                  15. If Tenant is a corporation, any dissolution, merger,
                  consolidation or other reorganization of Tenant, or the sale,
                  transfer or redemption of a direct or indirect controlling
                  interest in the capital stock of Tenant, in one or more
                  transactions, shall be deemed a voluntary assignment of this
                  Lease and subject to the provisions of this SECTION 15.
                  Neither this Lease nor any interest therein nor any estate
                  created thereby shall pass by operation of law or otherwise to
                  any trustee, custodian or receiver in bankruptcy of Tenant or
                  any assignee for the assignment of the benefit of creditors of
                  Tenant.

                                     26
<PAGE>

         (f)      Notwithstanding anything contained in this SECTION 15 to the
                  contrary, Tenant shall have the right, without Landlord's
                  consent, to assign or sublet all of the Premises to Permitted
                  Assignees (as hereinafter defined), provided that such
                  assignment or subletting shall not relieve Tenant of its
                  primary responsibility for the performance of all obligations
                  of Tenant hereunder, and in the event of an assignment to a
                  Permitted Assignee, such Permitted Assignee assumes, pursuant
                  to an agreement in form and substance reasonably satisfactory
                  to Landlord, the obligations of Tenant hereunder and in the
                  event of a sublet, such sublet is governed by a form of
                  sublease reasonably approved in advance by Landlord. As used
                  herein, a "Permitted Assignee" shall mean (i) any entity owned
                  or controlled by Tenant, (ii) any entity of which Tenant is a
                  subsidiary (on any level), (iii) any entity which is under
                  common ownership or control with Tenant, (iv) any entity into
                  which Tenant is merged or consolidated or which consolidates
                  into Tenant, (v) any entity which acquires all or
                  substantially all of the asset or stock of Tenant, or (vi) a
                  transaction in which Tenant becomes an entity whose shares of
                  stock or other ownership interests are, directly or
                  indirectly, sold on a national stock exchange or an
                  inter-dealer quotation system and in the event the foregoing
                  transaction has occurred any subsequent sale of ownership
                  interests or issuance of new ownership interests, directly or
                  indirectly in Tenant, provided in each case that Landlord is
                  reasonably satisfied with the business reputation and
                  financial condition of such entity, it being understood that
                  if such entity has a net worth at least equal to that of
                  Tenant on the date of such assignment, subletting or transfer
                  and maintains the Security Deposit Amount, the financial
                  condition of such entity shall be deemed satisfactory to
                  Landlord. Further, Tenant agrees to deliver to Landlord,
                  within ten (10) business days subsequent to the effective date
                  of such assignment or sublease, fully executed copies of the
                  documents effectuating such assignment or sublease.

16.      SURRENDER OF POSSESSION

         Upon the expiration of the Term or upon the termination of Tenant's
         right of possession, whether by lapse of time or at the option of
         Landlord as herein provided, Tenant shall forthwith surrender the
         Premises to Landlord in good order, repair and condition, ordinary wear
         and damage resulting from fire or other casualty and condemnation
         excepted. Any interest of Tenant in the alterations, improvements,
         installations and additions to the Premises made or paid for by
         Landlord or Tenant shall, without compensation to Tenant, become
         Landlord's property at the termination of this Lease by lapse of time
         or otherwise and such alterations, improvements, installations and
         additions shall be relinquished to Landlord in good condition, ordinary
         wear excepted. Prior to the termination of the Term or of Tenant's
         right of possession Tenant shall remove its office furniture, trade
         fixtures, office equipment and all other items of Tenant's movable
         property on the Premises. Unless requested to do so by Landlord, Tenant
         shall not have any right to remove, any alterations, improvements,
         installations or additions, which shall include built-in furniture or
         shelves and all other attached items, excluding trade fixtures. Tenant
         shall pay to Landlord upon demand the cost of repairing any damage to
         the Premises and to the Building caused by any such removal. If Tenant
         fails or refuses to remove any such property from the Premises, Tenant
         shall be conclusively presumed to have abandoned the same, and title
         thereto shall thereupon pass to Landlord without any

                                   27
<PAGE>

         cost either by set-off, credit, allowance or otherwise, and at its
         option Landlord may: (i) accept the title to the property; (ii) or at
         Tenant's expense remove the property or any part in any manner that
         Landlord shall choose, repairing any damage to the Premises caused by
         such removal; and store, destroy or otherwise dispose of the property
         without incurring liability to Tenant or any other person. Landlord
         expressly acknowledges and agrees that nothing contained in this Lease
         to the contrary (except as provided in the next sentence) shall require
         Tenant to remove any improvements or additions installed by or on
         behalf of Tenant pursuant to the Tenant Work Letter or any alterations
         performed by Tenant pursuant to SECTION 8 above (unless at the time
         Landlord shall approve the installation of such alterations, Landlord
         shall have notified Tenant in writing that such removal would be
         required at the expiration of the Term) or otherwise require Tenant to
         bring the Premises back to "raw space". Notwithstanding anything herein
         to the contrary, at Landlord's election, which may be made at any time
         up until sixty (60) days prior to the end of the Term, Tenant shall be
         obligated to remove any of the following designated by Landlord: the
         Network Operating Center, the Universal Transport Exchange and all
         conduit and cable installed in the Premises and the Building in
         connection therewith, and Tenant shall repair (or pay for the cost of
         repairing) any damage to the Premises and Building caused by such
         removal; if Landlord fails to designate that Tenant remove the same,
         Tenant shall leave the Network Operating Center, the Universal
         Transport Exchange, and/or such conduit and cable in the Premises and
         Building.

17.      HOLDING OVER

         During each month or portion thereof for which Tenant shall retain
         possession of the Premises or any portion thereof after the expiration
         or termination of the Term or of Tenant's right of possession, whether
         by lapse of time or otherwise, Tenant shall pay to Landlord an amount
         as Rent equal to 250% of the Base Rent and 250% of the Additional Rent
         payable by Tenant for the last month of the immediately prior Lease
         Year (i.e., the Lease Year which concluded on the day immediately
         preceding the first day of Tenant's hold over) for all of the Premises
         (regardless of whether Tenant retains possession of all or only a
         portion of the Premises) for each month Tenant so retains possession of
         the Premises (regardless of whether for all or only a portion of such
         month); provided, however, that during (x) the first three months
         rather than paying 250% as stated aforesaid, Tenant shall pay an amount
         as Rent equal to 150% of the Base Rent and 150% of the Additional Rent
         payable by Tenant for the last month of the immediately prior Lease
         Year for all of the Premises (regardless of whether Tenant retains
         possession of all or only a portion of the Premises) for each month
         Tenant retains possession of all or a portion of the Premises
         regardless of whether Tenant retains possession of all or a portion of
         such Premises for all or only a portion of such month; and (y) the
         second three months rather than paying 250% as stated aforesaid Tenant
         shall pay an amount as Rent equal to 200% of the Base Rent and 200% of
         the Additional Rent payable by Tenant for the last month of the
         immediately prior Lease Year for all of the Premises (regardless of
         whether Tenant retains possession of all or only a portion of the
         Premises) for each month Tenant retains possession of all or a portion
         of the Premises regardless of whether Tenant retains possession of all
         or a portion of the Premises for all or only a portion of such month.

         Tenant shall also pay all damages sustained by Landlord on account of
         Tenant's holding over; provided, however, that Tenant shall not be
         liable for consequential damages

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         incurred by Landlord during the first three months of such holding over
         if Tenant notifies Landlord in writing that it will be holding over for
         such three (3) month period on or before the date which is six months
         prior to the end of the Term. The provisions of this SECTION 17 shall
         not be deemed to limit or constitute a waiver of any other rights or
         remedies of Landlord provided herein or at law.

18.      ESTOPPEL CERTIFICATE

         Tenant agrees, that, from time to time upon not less than ten (10)
         business days prior written request by Landlord, Tenant, or Tenant's
         duly authorized representative having knowledge of the following facts,
         will deliver to Landlord a statement in writing certifying: (i) that
         this Lease is unmodified and in full force and effect (or if there have
         been modifications, a description of such modifications and that the
         Lease as modified is in full force and effect); (ii) the dates to which
         Rent and other charges have been paid; (iii) that the Landlord is not
         in default under any provision of this Lease, or, if in default, the
         nature thereof in detail; and (iv) such further matters as are set
         forth on the form of estoppel certificate attached hereto as EXHIBIT D
         and made a part hereof, or as may be reasonably requested by Landlord,
         it being intended that any such statement may be relied upon by any
         mortgagees or prospective mortgagees, or any prospective assignee of
         any Mortgagee, or any prospective and/or subsequent purchaser or
         transferee of all or a part of Landlord's interest in the Land and/or
         Building.

19.      OBLIGATIONS TO MORTGAGEES

         (a)      SUBORDINATION. This Lease is subject and subordinate to all
                  present and future ground or underlying leases of the Land
                  and/or improvement leases of the Building and to the lien of
                  any mortgages or trust deeds now and hereafter in force
                  against the Land or Building and to all renewals, extensions,
                  modifications, consolidation and replacements thereof other
                  than the Mortgages dated as of November 7, 1994 made by ST
                  Holdings, Inc. to Sears Roebuck and Co. and Partners Tower,
                  L.P. and filed as Document Nos. 94956335 (refiled as Document
                  No. 95106247) and 94956336. At Landlord's request (and after
                  consent from any prior mortgagee or lessor if Tenant has
                  agreed not to so subordinate without such consent), Tenant
                  shall execute such further instruments or assurances as
                  Landlord may deem necessary to evidence, confirm or effectuate
                  such subordination of this Lease thereto or, if requested, to
                  make Tenant's interest in this Lease superior thereto. If any
                  mortgage shall be foreclosed or property encumbered thereby is
                  transferred in lieu of foreclosure, or if any such future
                  ground or improvements lease or underlying lease is
                  terminated: (i) the liability of the mortgagee, trustee,
                  transferee, purchaser at such foreclosure sale or ground
                  lessor or improvements lessor and the liability of a
                  subsequent owner (all of the foregoing parties are
                  collectively referred to as "Mortgagee") shall exist only with
                  respect to the period during which the Mortgagee is the owner
                  of the Land or Building and the Mortgagee shall be released
                  from any further liability upon its transfer of ownership; and
                  (ii) the Mortgagee shall not have any liability whatsoever for
                  the acts of the Landlord prior to any such transfer nor any
                  liability for any deposits made by Tenant hereunder unless
                  Mortgagee has received such deposits; and (iii) Tenant hereby
                  agrees to attorn to and recognize as Landlord, Mortgagee or

                                    29
<PAGE>

                  any successor lessor under the Master Lease (as hereinafter
                  defined) and, upon request of the Mortgagee, will execute such
                  instruments as may be required by said Mortgagee or successor
                  lessor under the Master Lease; and (iv) so long as Tenant is
                  not in default hereunder Tenant's right to possession of the
                  Premises will not be disturbed and this Lease will not be
                  terminated.

         (b)      NOTICE TO LANDLORD AND MORTGAGEE. If any act or omission by
                  Landlord would give Tenant the right to damages from Landlord
                  or any rights with respect to this Lease, Tenant will not sue
                  for such damages or exercise any such rights (other than the
                  abatement of Rent set forth in SECTION 6(b) hereof) until (i)
                  it shall have given written notice of the act or omission to
                  Landlord and to the holder(s) of the indebtedness or other
                  obligations secured by any mortgage or deed of trust affecting
                  the Premises or of any ground or underlying lease, if the name
                  and address of such holder(s) have been furnished to Tenant;
                  and (ii) a reasonable period of time (in light both of the
                  time required to cure the act or omission and the effect of
                  the act or omission on Tenant's business operations in the
                  Premises) to cure the act or omission has elapsed following
                  the giving of the notice, during which time Landlord and such
                  holder(s), or either of them, their agents or employees, will
                  be entitled to enter upon the Premises and do therein whatever
                  may be necessary to cure the act or omission.

20.      CERTAIN RIGHTS RESERVED BY LANDLORD

         Landlord shall have the following rights, each of which Landlord may
         exercise without notice to Tenant (but subject to maintaining access to
         the Premises as described in subparagraph (iii) below), and without
         liability to Tenant for damage or injury to property, person or
         business on account of the exercise thereof, and the exercise of any
         such rights shall not be deemed to constitute an eviction or
         disturbance of Tenant's use or possession of the Premises and shall not
         give rise to any claim for set-off or abatement of rent or any other
         claim:

                  (i)      To change the name or street address of the Building.

                  (ii)     To install, affix and maintain any and all signs on
                           the exterior or interior of the Building.

                  (iii)    To decorate or to make repairs, alterations,
                           additions, installations or improvements, whether
                           structural or otherwise, in and about the Building,
                           or any part thereof, and for such purposes to enter
                           upon the Premises, and during the continuance of any
                           of said work, to temporarily close doors, entryways,
                           public space and corridors in the Building and to
                           interrupt or temporarily suspend services or use of
                           facilities, all without affecting any of Tenant's
                           obligations hereunder, so long as the Premises are
                           reasonably accessible and usable by Tenant.

                  (iv)     To furnish door keys, magnetic cards or electronic
                           access systems for the entry door(s) in the Premises
                           at the commencement of the Lease and to retain at all
                           times, and to use in appropriate instances, keys or
                           access cards to all doors within and into the
                           Premises. Tenant shall be permitted to

                                    30
<PAGE>

                           install a card key or other access control system
                           which shall, as Tenant shall elect, be in addition to
                           or in lieu of any pre-existing locks or card key or
                           other access control system; provided, however, that
                           if Tenant installs such a system Tenant shall furnish
                           a pass key or equivalent device to Landlord.
                           Notwithstanding the provisions for Landlord's access
                           to the Premises, Tenant relieves and releases
                           Landlord of all responsibility arising out of theft,
                           robbery, pilferage and personal assault, excluding
                           gross negligence or willful misconduct of Landlord or
                           its agents. Upon the expiration of the Term or
                           Tenant's right to possession, Tenant shall return all
                           keys and access cards to Landlord and shall disclose
                           to Landlord the combination of any safes, cabinets or
                           vaults left in the Premises.

                  (v)      To designate and approve all window coverings used in
                           the Building, including, without limitation, solar
                           window coverings.

                  (vi)     To approve the weight, size and location of safes,
                           vaults, vertical files and other heavy equipment and
                           articles in and about the Premises and the Building
                           so as not to exceed the legal live load per square
                           foot designated by the structural engineers for the
                           Building, and to require all such items and furniture
                           and similar items to be moved into or out of the
                           Building and Premises only at such times and in such
                           manner as Landlord shall direct in writing. Tenant
                           shall not install or operate machinery or any
                           mechanical devices of any nature not directly related
                           to Tenant's ordinary use of the Premises without the
                           prior written consent of Landlord. Movements of
                           Tenant's property into or out of the Building or
                           Premises and within the Building are entirely at the
                           risk and responsibility of Tenant, and Landlord
                           reserves the right to require permits before allowing
                           any property to be moved into or out of the Building
                           or Premises.

                  (vii)    To establish reasonable controls for the purpose of
                           regulating all property and packages, both personal
                           and otherwise, to be moved into or out of the
                           Building and Premises and all persons using the
                           Building after normal office hours.

                  (viii)   To regulate in a reasonable manner delivery and
                           service of supplies and the usage of the loading
                           docks, receiving areas and freight elevators.

                  (ix)     To show the Premises to prospective tenants (during
                           the last 15 months of the Term), lien holders and
                           purchasers at reasonable times upon prior notice to
                           Tenant.

                  (x)      To enter the Premises at any reasonable time to
                           inspect the Premises.

                  (xi)     If Landlord elects to make available to tenants in
                           the Building any services or supplies (or arranges a
                           master contract therefor), in the nature of messenger
                           services or other operational security features for
                           the Building, Tenant agrees to obtain its
                           requirements, if any, therefor from Landlord or under
                           any such contract, provided that the charges therefor
                           are reasonable,

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<PAGE>

                           and that the services contracted for are similar to
                           those provided in other buildings in downtown
                           Chicago.

21.      RULES AND REGULATIONS

         Tenant agrees to observe the rules and regulations for the Building
         attached hereto as EXHIBIT C and made a part hereof. Landlord shall
         have the right from time to time to prescribe additional reasonable
         rules and regulations for general application to all office tenants
         which, in its reasonable judgment, may be desirable for the use, entry,
         operation and management of the Premises and Building, each of which
         rules and regulations and any amendments thereto shall become a part of
         this Lease. Tenant shall comply with all of the rules and regulations;
         provided, however, that the rules and regulations shall not contradict
         or abrogate any right or privilege herein expressly granted to Tenant.
         Landlord shall use reasonable efforts to enforce such rules and
         regulations in a uniform non-discriminatory manner against all
         similarly situated tenants.

22.      DEFAULT AND LANDLORD'S REMEDIES

         (a)      DEFAULT. Any one or more of the following events shall be a
                  default ("Default") under this Lease: (i) If Tenant does not
                  pay the Rent or any installment thereof or does not pay any
                  other sum (other than replenishment of the Security Deposit
                  which is governed by clause (x) below) required to be paid by
                  Tenant under this Lease or under the terms of any other
                  agreement between Landlord (or Landlord's predecessors in
                  title) and Tenant and such default shall continue for five (5)
                  days after written notice to Tenant; or (ii) if Tenant fails
                  to observe or perform any of the other covenants or conditions
                  in this Lease which Tenant is required to observe and perform
                  and such default shall continue for twenty (20) days after
                  written notice to Tenant, provided, however, if such default
                  does not involve a hazardous condition and is susceptible to
                  cure but cannot, by the use of reasonable efforts, be cured
                  within twenty (20) days, Landlord shall not exercise any of
                  its remedies hereunder if and so long as (a) Tenant shall have
                  commenced to cure such default within twenty (20) days and (b)
                  Tenant shall thereafter continuously and diligently proceed to
                  cure such default in a manner reasonably satisfactory to
                  Landlord, and (c) such default shall be cured within sixty
                  (60) days of such notice to Tenant; or (iii) if a default is
                  made in the performance by Tenant of any covenant of this
                  Lease which involves a hazardous condition and is not cured by
                  Tenant promptly upon written notice to Tenant; or (iv) if the
                  interest of Tenant in this Lease shall be levied on under
                  execution or other legal process; or (v) if any voluntary
                  petition in bankruptcy or for corporate reorganization or any
                  similar relief shall be filed by TENANT; or (vi) if any
                  involuntary petition in bankruptcy shall be filed against
                  Tenant under any federal or state bankruptcy or insolvency act
                  and shall not have been dismissed within ninety (90) days from
                  the filing thereof; or (vii) if a receiver shall be appointed
                  for Tenant or any of the property of Tenant by any court and
                  such receiver shall not have been dismissed within ninety (90)
                  days from the date of his appointment; or (viii) if Tenant
                  shall make an assignment for the benefit of creditors; or (ix)
                  if Tenant shall admit in writing Tenant's inability to meet
                  Tenant's debts as they mature; or (x) if Tenant fails to
                  replenish the Security Deposit as provided in SECTION 29
                  hereof.

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<PAGE>

         (b)      LANDLORD'S REMEDIES. If a Default occurs, Landlord may, at its
                  sole option, with or without further notice or demand of any
                  kind to Tenant or any other person, have any one or more of
                  the following described remedies in addition to all other
                  rights and remedies provided at law or in equity or elsewhere
                  herein (provided that Landlord shall use such efforts as are
                  required by law to mitigate any damages resulting from such
                  Default):

                  (i)      Terminate this Lease and the Term created hereby and
                           immediately, repossess the Premises. If Landlord does
                           terminate this Lease and repossess the Premises,
                           Landlord shall be entitled to immediately recover, in
                           addition to any other sums or damages for which
                           Tenant may be liable to Landlord, as damages a sum of
                           money equal to the greater of: (1) the excess of the
                           present value of the Rent provided to be paid by
                           Tenant for the balance of the Term (disregarding any
                           unexpired period of initial Rent abatement) over the
                           present value of the anticipated fair market rent for
                           the Premises (computed based upon the yield on U.S.
                           Treasury obligations having a maturity closest to the
                           Termination Date) that could be achieved for said
                           period, after deduction of all anticipated expenses
                           of reletting, including, without limitation, all
                           allowances, abatements, construction costs, brokerage
                           commissions and tenant concessions likely to be
                           required under then-existing market conditions; or
                           (2) the unamortized portion of any rent abatements,
                           allowances, construction costs, brokerage commissions
                           and other costs incurred by Landlord in connection
                           with this Lease, as amortized on a straight-line
                           basis with interest on the unamortized amount at
                           twelve percent (12%) per annum over the initial Term
                           during which Base Rent is payable. Should the present
                           value of the anticipated fair market rent for the
                           Premises, after deduction of all anticipated expenses
                           of reletting, that could be achieved for the balance
                           of the Term exceed the present value of the Rent
                           provided to be paid by Tenant for the balance of the
                           Term, Landlord shall have no obligation to pay to
                           Tenant the excess or any part thereof or to credit
                           such excess or any part thereof against any other
                           sums or damages for which Tenant may be liable to
                           Landlord.

                  (ii)     Landlord may terminate Tenant's right of possession
                           and may repossess the Premises by forcible entry and
                           detainer suit, by taking peaceful possession or
                           otherwise, without terminating this Lease. If
                           Landlord terminates Tenant's right of possession
                           without terminating this Lease, Landlord shall take
                           reasonable measures to the extent required by law, to
                           relet the same for the account of Tenant, for such
                           rent and upon such terms as shall be reasonably
                           satisfactory to Landlord. Reasonable measures shall
                           not obligate Landlord to show the Premises before
                           showing other space in the Building to a prospective
                           tenant. For the purpose of such reletting, Landlord
                           is authorized to decorate, repair, remodel or alter
                           the Premises and to relet the Premises at such rental
                           rate (which may be higher than the rental rate then
                           applicable under this Lease), as Landlord reasonably
                           determines to be necessary to maximize the effective
                           rent on reletting. If Landlord shall fail to relet
                           the Premises, Tenant shall pay to

                                33
<PAGE>

                           Landlord as damages the amount of the Rent reserved
                           in this Lease for the balance of the Term as due
                           hereunder. If the Premises are relet and a sufficient
                           sum shall not be realized from such reletting after
                           paying all of the costs and expenses of all
                           decoration, repairs, remodeling, alterations,
                           installations and additions and the expenses of such
                           reletting (including all allowances, abatements and
                           other tenant concessions required under then-existing
                           market conditions), to satisfy the Rent provided for
                           in this Lease, Tenant shall satisfy and pay the same
                           upon demand therefor from time to time. Tenant shall
                           not be entitled to any rents received by Landlord in
                           excess of the Rent provided for in this Lease. Tenant
                           agrees that Landlord may file suit to recover any
                           sums falling due under the terms of this SECTION 22
                           from time to time and that no suit or recovery of any
                           portion due Landlord hereunder shall be any defense
                           to any subsequent action brought for any amount not
                           theretofore reduced to judgment in favor of Landlord.

         (c)      JURY TRIAL WAIVER. Each party hereto hereby waives its rights
                  to a trial by jury in any action or proceeding based upon or
                  related to the subject matter of this Lease and the business
                  relationship that is being established. This waiver is
                  knowingly, intentionally and voluntarily made by each party
                  hereto and each party hereto acknowledges neither the other
                  party nor any person acting on behalf of the other party has
                  made any representations of fact to include this waiver of
                  trial by jury or has taken any actions which in any way modify
                  or nullify its effect. Each party hereto acknowledges that
                  this waiver is a material inducement to enter into this Lease
                  and that the other party has already relied on this waiver in
                  entering into this Lease and that the other party will
                  continue to rely on this waiver in its future dealings
                  hereunder. Each party hereto 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.

23.      EXPENSES OF ENFORCEMENT

         The prevailing party shall be entitled to receive from the other party
         hereto upon demand all reasonable costs, charges and expenses including
         the reasonable fees and out-of-pocket expenses of counsel (including
         in-house attorneys), agents and others retained by the prevailing party
         incurred in enforcing the obligations hereunder against the other party
         hereto.

24.      COVENANT OF QUIET ENJOYMENT

         Landlord covenants that Tenant, on paying the Rent, charges for
         services and other payments herein reserved and on keeping, observing
         and performing all the other terms, covenants, conditions, provisions
         and agreements herein contained on the part of Tenant to be kept,
         observed and performed, shall, during the Term, peaceably and quietly
         have, hold and enjoy the Premises subject to the terms, covenants,
         conditions, provisions and agreements hereof.

                                   34
<PAGE>

25.      REAL ESTATE BROKER

         Each party represents that it has dealt with (and only with) the
         Broker(s) specified in ITEM 9 of the SCHEDULE as broker in connection
         with this Lease, and that insofar as such party knows, no other brokers
         negotiated this Lease or are entitled to any commissions in connection
         therewith. Each party agrees to indemnify, defend and hold the other
         and its employees, agents, their officers and partners, harmless from
         and against any claims resulting from a breach of the foregoing
         representation. Landlord agrees to pay the Brokers in accordance with
         the terms of the separate agreements between such Broker and Landlord.

26.      MISCELLANEOUS

         (a)      RIGHTS CUMULATIVE. All rights and remedies of Landlord under
                  this Lease shall be cumulative and none shall exclude any
                  other rights and remedies allowed by law.

         (b)      INTEREST. All payments becoming due under this Lease and
                  remaining unpaid when due shall bear interest until paid at
                  the greater of (i) twelve percent (12%) per annum or (ii) four
                  percent (4%) per annum above the Prime Rate (as such term is
                  defined in SECTION 3(a)(ii)d hereof) .

         (c)      TERMS. The necessary grammatical changes required to make the
                  provisions hereof apply either to corporations or partnerships
                  or individuals, men or women, as the case may require, shall
                  in all cases be assumed as though in each case fully
                  expressed. Tenant acknowledges that "Rentable Area" as used in
                  this Lease includes a portion of the common and service areas
                  of the Building. Landlord makes no representation or warranty
                  as to the rentable or usable square footage of the Premises,
                  and Tenant agrees that Landlord's determination of the
                  Rentable Area of the Premises and Tenant's Proportionate Share
                  shall be conclusive and binding upon Tenant absent manifest
                  error.

         (d)      BINDING EFFECT. Each of the provisions of this Lease shall
                  extend to and shall, as the case may require, bind or inure to
                  the benefit not only of Landlord and of Tenant, but also of
                  their respective successors or assigns, provided this clause
                  shall not permit any assignment by Tenant contrary to the
                  provisions of SECTION 15 hereof.

         (e)      LEASE CONTAINS ALL TERMS. All of the representations and
                  obligations of Landlord and Tenant are contained herein and in
                  the Work Letter and other Exhibits attached hereto, and no
                  modification, waiver or amendment of this Lease or of any of
                  its conditions or provisions shall be binding upon the
                  Landlord or Tenant unless in writing signed by such party or
                  by a duly authorized agent of such party empowered by a
                  written authority signed by such party.

         (f)      DELIVERY FOR EXAMINATION. Submission of the Lease for
                  examination shall not bind Landlord in any manner, and no
                  Lease or obligations of the Landlord shall arise until this
                  instrument is signed by both Landlord and Tenant and delivery
                  is made to each.

                                35
<PAGE>

         (g)      NO AIR RIGHTS. No rights to any view or to light or air over
                  any property, whether belonging to Landlord or any other
                  person, are granted to Tenant by this Lease.

         (h)      MODIFICATION OF LEASE. If (i) any lender requires, as a
                  condition to its lending funds the repayment of which is to be
                  secured by a mortgage or trust deed on the Land and Building
                  or either, or (ii) the fee owner of the Land requires, as a
                  condition to entering into a ground lease with Landlord or a
                  lease of the entire Building with Landlord, that certain
                  modifications be made to this Lease, which modifications will
                  not require Tenant to pay any additional amounts or otherwise
                  change materially the rights, benefits or obligations of
                  Tenant hereunder, Tenant shall, upon Landlord's request,
                  execute appropriate instruments effecting such modifications.

         (i)      TRANSFER OF LANDLORD'S INTEREST. Landlord is Lessee under a
                  Master Lease dated as of November 7, 1994 ("Master Lease")
                  with State Street Bank and Trust Company as Trustee under the
                  233 South Wacker Drive Trust ("Beneficial Fee Owner") and
                  Chicago Title and Trust Company Trust No. 1095841 (the "Land
                  Trustee") under a Trust Agreement dated June 12, 1990. Tenant
                  agrees that Landlord has the right to transfer its interest in
                  the Land and Building and in this Lease. If such a transfer
                  occurs, Landlord shall automatically be released from all
                  liability under this Lease arising after the date of such
                  transfer and Tenant agrees to look solely to such transferee
                  for the performance of Landlord's obligations hereunder
                  arising after the date of such transfer. Tenant further
                  acknowledges that the Landlord may assign its interest in this
                  Lease to a mortgage lender as additional security and agrees
                  that such an assignment shall not release Landlord from its
                  obligations hereunder and that Tenant shall continue to look
                  to Landlord for the performance of its obligations hereunder.

         (j)      LANDLORD'S TITLE. Nothing herein contained shall empower
                  Tenant to commit or engage in any act which can, shall or may
                  encumber the estate of Landlord or the title of the Beneficial
                  Fee Owner or Land Trustee. The Master Lease provides in part:

                                    4.3 RECOGNITION BY TOWER OWNER. Tower Owner
                           expressly agrees that: (a) Master Lessee may enter
                           into leases (and other agreements) extending beyond
                           the Term of this Master Lease; (b) all leases and all
                           tenant's rights thereunder (and other agreements and
                           the rights of contracting parties thereunder) will
                           under no circumstances ever be terminated or impaired
                           as a result of any termination, modification,
                           assignment or surrender of this Master Lease; and (c)
                           in the event of any termination, modification,
                           assignment or surrender of this Master Lease, all
                           leases and agreements shall remain in full force and
                           effect as direct leases or agreements between Tower
                           Owner (or Master Lessee's successor or assign) and
                           such tenants (or contracting parties). Master Lessee
                           may, on behalf and in the name of Tower Owner,
                           execute any and all recognition, non-disturbance and
                           other agreements that Master Lessee deems appropriate
                           to assure to tenants of the Tower Real Property (or

                                   36
<PAGE>

                           contracting parties) that the provisions of their
                           leases (and agreements) will continue throughout
                           their entire term (including all extension and
                           renewal options), notwithstanding any termination,
                           modification or surrender of this Master Lease.

         (k)      PROHIBITION AGAINST RECORDING. Neither this Lease, nor the
                  Subordination, Non-Disturbance and Attornment Agreement, nor
                  any memorandum, affidavit or other writing with respect
                  thereto, shall be recorded by Tenant or by anyone acting
                  through, under or on behalf of Tenant, and the recording
                  thereof in violation of this provision shall make this Lease
                  null and void at Landlord's election.

         (l)      CAPTIONS. The captions of Sections, Subsections, Paragraphs
                  and Subparagraphs are for convenience only and shall not be
                  deemed to limit, construe, affect or alter the meaning of such
                  Sections, Subsections, Paragraphs or Subparagraphs.

         (m)      COVENANTS AND CONDITIONS. All of the covenants of Tenant
                  hereunder shall be deemed and construed to be "conditions," if
                  Landlord so elects, as well as "covenants" as though the words
                  specifically expressing or importing covenants and conditions
                  were used in each separate instance.

         (n)      ONLY LANDLORD/TENANT RELATIONSHIP. Nothing contained in this
                  Lease shall be deemed or construed by the parties hereto or by
                  any third party to create the relationship of principal and
                  agent, partnership, joint venturer or any association between
                  Landlord and Tenant, it being expressly understood and agreed
                  that neither the method of computation of Rent nor any act of
                  the parties hereto shall be deemed to create any relationship
                  between Landlord and Tenant other than the relationship of
                  landlord and tenant.

         (o)      APPLICATION OF PAYMENTS. Landlord shall have the right to
                  apply payments received from Tenant pursuant to this Lease
                  (regardless of Tenant's designation of such payments) to
                  satisfy any obligations of Tenant hereunder, in such order and
                  amounts, as Landlord in its sole discretion, may elect.

         (p)      DEFINITION OF LANDLORD. All indemnities of Tenant contained
                  herein which inure to the benefit of Landlord shall be
                  construed to also inure to the benefit of (i) Landlord's
                  beneficiaries if Landlord is a trust, (ii) Landlord's partners
                  if Landlord is a partnership, (iii) Landlord's shareholders,
                  officers and directors if Landlord is a corporation, and (iv)
                  the Beneficial Fee Owner and Land Trustee, (v) any current or
                  future mortgagees of the Land and/or Building, (vi) the
                  successors and assigns of any of the foregoing, and (vii) the
                  respective beneficiaries, shareholders, directors, officers,
                  partners, agents and employees, agents, managers, affiliates
                  and employees of any persons mentioned in clauses (i) through
                  (vi) above.

         (q)      TIME OF ESSENCE. Time is of the essence of this Lease and each
                  of its provisions.

         (r)      GOVERNING LAW. Interpretation of this Lease shall be governed
                  by the laws of the State of Illinois.

                                37
<PAGE>

         (s)      PARTIAL INVALIDITY. If any term, provision or condition
                  contained in this Lease shall, to any extent, be invalid or
                  unenforceable, the remainder of this Lease (or the application
                  of such term, provision or condition to persons or
                  circumstances other than those in respect to which it is
                  invalid or unenforceable) shall not be affected thereby, and
                  each and every other term, provision and condition of this
                  Lease shall be valid and enforceable to the fullest extent
                  possible permitted by law.

         (t)      PARKING. Tenant shall have the right to license (i) four
                  reserved spaces (subject to availability) in the parking
                  garage located in the Building and (ii) so long as an
                  affiliate of Landlord owns the property directly east of the
                  Sears Tower bounded by Wells, Franklin, Adams and Jackson
                  Streets and is operating the same as a garage, ten reserved
                  parking spaces in such garage. Such right shall be for the
                  benefit of Tenant but individual partners or employees of
                  Tenant may sign the individual parking agreements required for
                  parking in such garage, provided Tenant guarantees the same.
                  Tenant or its partners or employees may cease at any time
                  during the Term to license any such spaces, and after so doing
                  Tenant and its partners and employees shall no longer have any
                  right to use or license and shall have no further obligation
                  to pay for such parking spaces; provided, however, if Tenant
                  or its partners or employees shall thereafter desire to again
                  license such space(s) or shall desire to license additional
                  spaces, Tenant and its partners and employees may thereafter
                  license such spaces in the parking garages subject to
                  availability. Tenant's (and its partners and employees) use of
                  such parking spaces shall be subject to Landlord's "Rules and
                  Regulations for Garage Parkers" as the same may from time to
                  time be reasonably modified. Landlord may terminate any
                  license for a parking space for rule infractions. In addition,
                  Landlord may terminate any license for a parking space for
                  failure to pay the monthly parking charges therefor. The
                  monthly parking rate for reserved spaces in the Building
                  garage is $460 per space per month; the monthly parking rate
                  for reserved spaces in the garage located across from the
                  Sears Tower is $350 per space per month; either or both of
                  such rates may be adjusted by Landlord from time to time.

         (u)      GENERATOR. Tenant shall have an option during the first
                  twenty-four (24) months of the Term to lease a generator pad
                  located in the room on Lower Level I of the Building shown on
                  EXHIBIT F attached hereto and made a part hereof (the
                  "Generator Pad"), such pad being approximately 72 square feet
                  plus such additional area required for circulation and
                  partitions as required by applicable codes and/or Landlord's
                  reasonable requirements. If Tenant exercises its right to
                  lease the Generator Pad by giving Landlord written notice
                  thereof within such twenty-four (24) month period, Landlord
                  and Tenant shall enter into an amendment to this Lease in form
                  and substance reasonably satisfactory to Landlord
                  incorporating the Generator Pad into this Lease on the terms
                  and conditions contained herein, except that the rent for the
                  Generator Pad will be $30 per square foot gross. If Tenant
                  exercises its right and executes the amendment incorporating
                  the Generator Pad into the Lease, Tenant may, in accordance
                  with SECTION 8 of this Lease, install a 500 kilowatt gas-fired
                  standby generator to furnish standby electricity for Tenant's
                  Premises and the equipment located


                                     38
<PAGE>

                  therein. All gas used by Tenant shall be paid for by Tenant.
                  In the event Tenant installs the generator, Tenant may also
                  install (in accordance with the provisions of SECTION 8
                  hereof) three (3) - four inch (4") and one (1) - one inch (1")
                  conduits to connect the Premises to the generator power
                  connection point. The location, path, installation methods and
                  removal methods for such conduit are subject to Landlord's
                  sole determination. The monthly charge for each four inch (4")
                  conduit is $450 and the monthly charge for each one inch (1")
                  conduit is $250. The charges for the generator pad and conduit
                  shall be considered part of the Rent due under the Lease.

                  In the event Tenant does not so elect to lease the Generator
                  Pad during the first twenty-four (24) months of the Term and
                  enter into an amendment to the Lease as heretofore provided,
                  if Tenant thereafter expresses an interest in leasing the
                  Generator Pad and such Generator Pad is still available for
                  leasing, Landlord will use reasonable efforts to accommodate
                  Tenant at Landlord's then market rates.

         (v)      SIGNAGE. Tenant will have the right to hang a 3-dimensional
                  structural logo (but not lettering) at locations 1 and 2
                  designated on EXHIBIT G attached hereto and made a part
                  hereof. Each structural logo will be approximately three (3)
                  feet in diameter similar to the logo shown on EXHIBIT G, made
                  of polished and brushed stainless steel, and will be hung by
                  properly sized wire inside the glass wall of the Third Floor
                  Premises. Tenant will also have the right to install Tenant's
                  logo (including lettering) in the Third Floor Premises in
                  location 3 designated on EXHIBIT G. Such logo will be of
                  approximately the same dimensions as the signage currently
                  located at location 3 and will be of polished stainless steel.
                  At such times during the Term that Tenant occupies at least
                  206,000 square feet of Rentable Area (and for so long as
                  Tenant occupies at least 175,000 square feet of Rentable Area)
                  and provided more than six (6) years remains on the original
                  Term of the Lease, Tenant shall be granted the right to
                  signage in the 3-10 floor elevator bank in the lobby of the
                  Building. Such sign shall be comparable in size and design to
                  the sign of Bank of America located in the 23-28 elevator bank
                  in the lobby of the Building. The cost of installing,
                  maintaining and removing all signs and restoring the Premises
                  shall be the sole cost of Tenant.

27.      NOTICES

         (a)      All notices to be given under this Lease shall be in writing
                  and delivered either (i) personally upon an officer of
                  Landlord or Tenant, as the case may be, or (ii) by depositing
                  such notice in the United States mail, certified or registered
                  mail with return receipt requested, postage prepaid, or (iii)
                  via reputable overnight air courier service (such as Federal
                  Express or Airborne) and in every case addressed as set forth
                  in the SCHEDULE or if no address for Tenant is inserted in the
                  SCHEDULE, addressed to Tenant at Tenant's present address,
                  and, after occupancy of the Premises by Tenant, to Tenant at
                  233 South Wacker Drive, Chicago, Illinois 60606.

         (b)      Notice via personal service shall be deemed to have been given
                  when actually delivered. Notice given by certified or
                  registered mail shall be deemed to have


                                       39
<PAGE>

                  been given on the second business day after the date that the
                  notice is deposited into the mail postage prepaid. Notice
                  given via air courier shall be deemed given one (1) business
                  day after it is accepted by said courier for next day
                  delivery.

         (c)      Either Landlord or Tenant may change the location at which it
                  receives notices to another location within the United States
                  of America upon not less than ten (10) days notice to the
                  other pursuant to this SECTION 27.

28.      LIMITATION OF LIABILITY

         Tenant, and any person claiming an interest in the Premises through or
         under Tenant, each agree to look solely to the interests of Landlord,
         Beneficial Fee Owner and Land Trustee from time to time in the Land and
         Building, and no judgments against such persons may be satisfied out of
         any other assets. In no event shall Landlord, Beneficial Fee Owner or
         Land Trustee (or any of their respective officers, directors, agents,
         advisors, managers, shareholders, partners, beneficiaries, affiliates
         or successors and assigns) ever have any personal liability for any
         covenant, agreement, obligation, warranty, representation, indemnity or
         undertaking under this Lease or otherwise or be answerable or liable in
         any equitable, judicial or administrative proceeding or order.

29.      SECURITY DEPOSIT

         (a)      Landlord's obligations and Tenant's rights hereunder are
                  expressly conditioned upon Tenant depositing with Landlord
                  Letters of Credit (as defined in subparagraph (b) below)
                  aggregating the Security Deposit Amount (as defined in
                  subparagraph (b) below) as the Security Deposit specified in
                  ITEM 7 of the SCHEDULE, 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. Such
                  Letters of Credit shall be deposited by Tenant as follows: (i)
                  a Letter of Credit in the amount of $2,500,000.00 on or before
                  April 1, 2000, (ii) a Letter of Credit in the amount of
                  $2,000,000.00 on or before June 1, 2000, (iii) a Letter of
                  Credit in the amount of $1,500,000.00 on or before August 1,
                  2000, (iv) a Letter of Credit in the amount of $1,000,000.00
                  on or before October 1, 2000, (v) a Letter of Credit in the
                  amount of $500,000.00 on or before December 1, 2001, and (vi)
                  if Tenant exercises the Expansion Option, a Letter of Credit
                  in the amount of $400,000.00 on or before September 1, 2004.

         (b)      The term "Letter of Credit" as used herein shall mean an
                  irrevocable, unconditional letter of credit, in form and
                  substance acceptable to Landlord in Landlord's sole judgment,
                  expiring no earlier than one (1) year from the date of its
                  issuance in the amounts stated above in subparagraph (a)
                  issued by American National Bank and Trust Company of Chicago,
                  or another national bank acceptable to Landlord in Landlord's
                  sole discretion, which Letter of Credit (i) shall be payable
                  to Landlord upon demand made pursuant to presentation of an
                  unconditional sight draft with an accompanying certificate
                  stating that Landlord is entitled to draw upon the Letter of
                  Credit pursuant to terms of this Lease, and (ii) shall be
                  renewed as hereafter provided in subparagraph (d) below. The
                  term "Security Deposit Amount" as used herein shall mean
                  $7,500,000.00, increased to $7,900,000.00 in the event Tenant
                  exercises its Expansion Option; provided,


                                      40
<PAGE>

                  however, if there does not then exist a default or breach by
                  Tenant of its obligations or liabilities under this Lease then
                  the Security Deposit Amount shall be decreased as follows:

                  (w)      if Tenant has as of December 1, 2002 a net current
                           asset balance of at least $100,000,000.00 as shown on
                           its most recent quarterly balance sheet (the "Asset
                           Test") then the Security Deposit Amount shall be
                           reduced by $750,000.00 on December 1 of each year
                           commencing December 1, 2002, but never below the
                           amounts set forth in clause (y) below; provided,
                           however, that in the event Tenant fails to
                           demonstrate that it has maintained an asset balance
                           of $100,000,000.00 the Security Deposit Amount and
                           Letters of Credit shall cease to reduce further
                           unless Tenant again meets the Asset Test; and

                  (x)      if Tenant passes the Asset Test and achieves a
                           "Triple B" bond rating by a reputable rating agency
                           reasonably approved by Landlord (the "Triple B Bond
                           Test") on any December 1 occurring on or after
                           December 1, 2002, then the Security Deposit Amount
                           shall be reduced by $1,500,000.00 on December 1 of
                           each year commencing in the year of or after 2002
                           (but without doubling up with a reduction based on
                           clause (w) above, i.e., a $1,500,000.00 reduction,
                           not a $2,250,000.00 reduction) in which Tenant
                           achieves such bond rating, but never below the
                           amounts set forth in clause (y) below; provided,
                           however, that, in the event Tenant fails to maintain
                           such Triple B bond rating the Security Deposit Amount
                           and Letters of Credit shall cease to reduce further
                           unless Tenant again meets the Triple B Bond Test;
                           provided, further, however, that if at the time
                           Tenant fails to maintain the Triple B bond rating
                           Tenant meets and maintains the Asset Test, at that
                           point in time that the Security Deposit Amount and
                           Letters of Credit equal the amount which Tenant would
                           have been required to deposit pursuant to clause (w)
                           above, Tenant shall again be able to reduce the
                           Security Deposit Amount and Letters of Credit in
                           accordance with clause (w) above; and

                  (y)      if Tenant passes the Asset Test and achieves an "A"
                           bond rating or better by a reputable rating agency
                           reasonably approved by Landlord (the "A Bond Test")
                           on any December 1 occurring during or after calendar
                           year 2006, then the Security Deposit Amount shall be
                           reduced to $750,000.00 for the balance of the Term or
                           $817,000.00 for the balance of the Term if Tenant has
                           exercised the Expansion Option; provided, however,
                           that, in the event Tenant fails to maintain such A
                           bond rating the Security Deposit Amount and Letters
                           of Credit shall be reinstated to that amount which
                           Tenant would have been required to deposit but for
                           this clause (y) in accordance with clauses (w) and
                           (x) above and Tenant shall increase the Security
                           Deposit Amount and Letters of Credit accordingly; and

                  (z)      if Tenant exercises the Expansion Option and (i) has
                           met the Asset Test, the Letter of Credit to be
                           furnished on September 1, 2004 shall be reduced from
                           $400,000.00 to $333,000.00 and the $750,000.00 number
                           referenced


                                      41
<PAGE>

                           in clause (w) above shall be $817,000.00, or (ii) has
                           met the Triple B Bond Test, the Letter of Credit to
                           be furnished on September 1, 2004 shall be reduced
                           from $400,000.00 to $266,000.00 and the $1,500,000.00
                           number referenced in clause (x) above shall be
                           $1,634,000.00.

         (c)      If Tenant fails to perform any of its obligations hereunder,
                  Landlord may use, apply or retain such part of the Security
                  Deposit as necessary for the payment of: (i) any Rent or other
                  sums of money which Tenant may not have paid when due (after
                  the expiration of all notice and cure periods, if any); (ii)
                  any sum expended by Landlord on behalf of Tenant in accordance
                  with the provisions of this Lease; or (iii) any sum which
                  Landlord may expend or be required to expend by reason of a
                  Default by Tenant, including, without limitation, any damage
                  or deficiency in or from the reletting of the Premises as
                  provided in SECTION 22 hereof. The use, application or
                  retention of the Security Deposit, 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 Security Deposit) and shall not operate as a
                  limitation on any recovery to which Landlord may otherwise be
                  entitled. If any portion of the Security Deposit is used,
                  applied or retained by Landlord for the purposes set forth
                  above, Tenant agrees, within ten (10) days after the written
                  demand therefor is made by Landlord, to reinstate the Letters
                  of Credit to the full Security Deposit Amount determined
                  pursuant to subparagraph (b) above.

         (d)      No later than thirty (30) days prior to the expiration of any
                  Letter of Credit then deposited hereunder, Tenant shall
                  deliver to Landlord a new Letter of Credit expiring not
                  earlier than one (1) year from the expiration of the prior
                  Letter of Credit and meeting all of the other requirements set
                  forth herein or an amendment to the existing Letter of Credit
                  extending the maturity date thereof for one (1) year. In the
                  event Tenant fails to timely provide such substitute Letter of
                  Credit or amendment to the existing Letter of Credit, Landlord
                  shall be entitled to draw the full amount of the existing
                  Letter of Credit.

         (e)      If Tenant shall fully and faithfully comply with all of the
                  provisions of this Lease, the Security Deposit, 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, and following the payment by
                  Tenant of any deficiency owed by Tenant with respect to the
                  Expense Adjustment Amount or the Tax Adjustment Amount for the
                  final Lease Year hereof following the reconciliation thereof
                  in accordance with SECTIONS 3(b) and 3(d) hereof. In the
                  absence of evidence satisfactory to Landlord of any permitted
                  assignment of the right to receive the Security Deposit, or of
                  the remaining balance thereof, Landlord may return the same to
                  the original Tenant, regardless of one or more assignments of
                  Tenant's interest in this Lease or the Security Deposit. In
                  such event, upon the return of the Security Deposit, or the
                  remaining balance thereof to the original Tenant, Landlord
                  shall be completely relieved of liability under this SECTION
                  29 or otherwise with respect to the Security Deposit.


                                      42
<PAGE>

         (f)      Tenant acknowledges that Landlord has the right to transfer or
                  mortgage its interest in the Land and the Building and in this
                  Lease and Tenant agrees that if such a transfer or mortgage
                  occurs, Landlord shall have the right to transfer or assign
                  the Security Deposit to the transferee or mortgagee. Upon such
                  transfer or assignment, Landlord shall thereby be released by
                  Tenant from all liability or obligation for the return of such
                  Security Deposit and Tenant shall look solely to such
                  transferee or mortgagee for the return of the Security
                  Deposit.

30.      RIGHT OF FIRST OFFER

         If at any time any space becomes available for leasing to tenants not
         then occupying space in the Building on the 3rd, 4th, 7th or 8th floors
         of the Building, and if Tenant is not then in Default hereunder, then
         Landlord shall not lease such space to any party without first giving
         Tenant (i) notice of the availability of such space which shall include
         a description of the space, the proposed term and rental rate
         (including escalations, if any), abatements and allowances, if any, and
         other economic concessions that Landlord believes that it would agree
         to with respect to such space (the "Offered Terms") and (ii) ten (10)
         days after the date of such notice in which to commit in writing to
         lease such space on the Offered Terms for the remainder of Term, taking
         into account any modifications in such Offered Terms required by the
         fact that the remaining Term may be longer or shorter than that
         proposed by Landlord, and otherwise on the terms, covenants and
         conditions contained in this Lease. If Tenant fails, refuses or is
         otherwise unable to commit to such a lease for all of such space
         offered within the 10-day period, Landlord shall have the right to
         lease the space to any third party or parties on such terms as are
         acceptable to Landlord.

31.      EXPANSION OF PREMISES

         (a)      EXPANSION SPACES. Tenant shall have the right (the "Expansion
                  Option") hereinafter described in this SECTION 31 to expand
                  the Premises by leasing approximately 12,949 square feet of
                  Rentable Area on the eighth (8th) floor of the Building
                  identified herein and on Exhibit A-6 as the "Expansion Space"
                  on or about September 1, 2004 (the "Expansion Date"). Tenant
                  shall exercise its right to add such Expansion Space by
                  written notice to Landlord given no later than September 1,
                  2003. If Tenant fails to give the advance notice required
                  herein to Landlord by the specified date with respect to the
                  Expansion Space, Tenant will be deemed to have declined to
                  exercise its right to lease such Expansion Space.

         (b)      MECHANICS OF EXPANSION. Upon the exercise by Tenant of its
                  right to expand as provided in this SECTION 31, Landlord and
                  Tenant shall promptly proceed to enter into a written
                  agreement modifying this Lease to include such Expansion Space
                  in the Premises. The Expansion Space so included will be
                  considered to be a part of the Premises as of the Expansion
                  Date, subject to the provisions of SECTION 31(d) hereof. The
                  Expansion Spaces shall be governed by all the terms of this
                  Lease, except that (i) Tenant's Proportionate Share shall be
                  increased accordingly, (ii) the Base Rent for the Expansion
                  Space will be at the then escalated rate under this Lease and
                  thereafter escalated as set forth in Schedule 1, (iii)
                  possession of the Expansion Space shall be delivered to Tenant
                  in an "as is" condition,


                                      43
<PAGE>

                  provided, however, Landlord shall pay Tenant a construction
                  Allowance in the amount of $22.12 per square foot of Rentable
                  Area in the Expansion Space in accordance with Landlord's then
                  standard Work Letter, and (iv) Tenant shall commence to pay
                  Rent for the Expansion Space on the earlier to occur of (x)
                  one hundred twenty days after Landlord tenders delivery
                  thereof to Tenant and (y) the date Tenant occupies the
                  Expansion Space for the conduct of its business therefrom. In
                  the event Tenant fails for any reason to execute and deliver
                  the lease amendment within twenty (20) business days of
                  Tenant's receipt of the same (including, Tenant's desire to
                  withdraw its exercise of the Expansion Option during such
                  twenty (20) business day period) Tenant's purported exercise
                  of its Renewal Option shall be of no force or effect and the
                  Expansion Option shall become null and void.

         (c)      DELAYS. Landlord will use reasonable diligence to make the
                  Expansion Space available to Tenant on the Expansion Date. If
                  Landlord is unable to do so for reasons beyond landlord's
                  reasonable control (however, Landlord's leasing of Expansion
                  Space to other tenants shall be deemed to be within Landlord's
                  control), Landlord will not be liable for such failure or
                  inability, nor shall this failure or inability impair the
                  validity of this Lease, nor extend the Term, but the Expansion
                  Space will not become a part of the Premises, and therefore
                  the commencement of Tenant's obligation to pay Rent on such
                  space shall be deferred, until possession is delivered to
                  Tenant.

         (d)      CONDITIONS TO EXERCISE. If on the date when Tenant notifies
                  Landlord of its election to exercise the Expansion Option,
                  Tenant shall be in Default hereunder or otherwise in default
                  in the performance of any of the terms, covenants or
                  conditions contained in this Lease, or if at any time
                  following the exercise of the Expansion Option and prior to
                  the applicable date that Tenant is to take possession of the
                  Expansion Space Tenant shall be in Default hereunder or
                  otherwise in default in the performance of any of the terms,
                  covenants or conditions contained in this Lease, Landlord
                  shall have the option, on written notice to Tenant, to declare
                  Tenant's election to expand to be void and of no effect.

32.      TENANT'S OPTION TO RENEW

         The Tenant is hereby granted one (1) five (5) year option to renew the
         Lease ("Renewal Option"). If the Tenant desires to exercise the Renewal
         Option, it shall so notify the Landlord, in writing, not later than the
         first day of the fifteenth (15th) month prior to the then current
         expiration date of the Term. Such notice shall only be effective if
         delivered at a time when the Tenant is not in Default hereunder or
         otherwise in default in the performance of any of its obligations under
         the terms and provisions of this Lease. Within thirty (30) days
         following its receipt of Tenant's notice of its desire to exercise the
         Renewal Option, given at the time and in the manner provided above,
         Landlord shall prepare and transmit to Tenant an appropriate amendment
         to this Lease extending the Term for five (5) years ("Extended Term")
         and specifying (i) the Base Rent for such extension, which shall be the
         base rental rate then being offered and accepted by Landlord to other
         tenants of comparable size and location renewing leases in the


                                      44
<PAGE>

         Building, as reasonably determined by Landlord and evidenced by recent
         transactions which shall be disclosed to Tenant ("Market Rent") and
         (ii) that all other terms and conditions during the Extended Term are
         the same as those during the Term, except for any expansion rights,
         reduction rights or limitations on taxes and operating expenses. In the
         event the Tenant shall fail for any reason to execute and deliver the
         lease amendment within twenty (20) business days of Tenant's receipt of
         the same (including Tenant's desire to withdraw its exercise of the
         Renewal Option during such twenty (20) business day period), Tenant's
         purported exercise of its Renewal Option shall be of no force or effect
         and the Renewal Option and any subsequent Renewal Options shall become
         null and void. In the event Tenant shall be in Default hereunder or
         otherwise in default in the performance of any of its obligations under
         the terms and provisions of this Lease at the commencement date of any
         Extended Term, then in either such event, at Landlord's option,
         Tenant's purported exercise of its Renewal Option shall be of no force
         or effect and the Renewal Option and any subsequent Renewal Options
         shall become null and void.

         IN WITNESS WHEREOF, the parties have executed this Lease as of the day
and year first above written.

                                    LANDLORD:

                                    TH TOWER LEASING LLC,
                                    A DELAWARE LIMITED LIABILITY COMPANY

                                    By:  /s/ Stephen E Budorick
                                             Its Vice President

                                    TENANT:

                                    UNIVERSAL ACCESS, INC.,
                                    A DELAWARE CORPORATION

                                    By:  /s/ Robert Brown
                                             Its  Vice President


                                      45
<PAGE>




                                    EXHIBIT A

                             FLOOR PLAN OF PREMISES


                                     A-1
<PAGE>

                                    EXHIBIT B

                               TENANT WORK LETTER

         This is the Tenant Work Letter referred to in the Lease of even date
herewith (the "Lease") wherein UNIVERSAL ACCESS, INC., a Delaware corporation
("Tenant"), has agreed to lease certain space from TH Tower Leasing LLC, a
Delaware limited liability company ("Landlord"), at 233 South Wacker Drive,
Chicago, Illinois. Unless otherwise defined herein, all capitalized terms used
herein shall have the respective meanings assigned to them in the Lease. Tenant
may elect to install the initial improvements to the Premises in stages at
different times for different portions of the Premises, in which case this
Tenant Work Letter shall be applied separately to each stage ("Stage") as work
is performed in each portion of the Premises. The term Premises as used herein
shall mean that portion of the Premises in such Stage.

1.       TENANT'S WORK

         (a)      Tenant shall provide the construction material, hardware and
                  equipment and the labor to construct and install the
                  improvements to the Premises described in the Plans (as that
                  term is hereinafter described). The material, hardware and
                  equipment as incorporated into the Premises pursuant to the
                  Plans are herein collectively referred to as the "Tenant's
                  Work". Subject to the provisions of this Work Letter, Tenant
                  shall proceed diligently to cause the Tenant's Work approved
                  by Landlord to be completed in accordance with the terms and
                  conditions of the Lease and this Work Letter. Notwithstanding
                  anything contained herein to the contrary, Tenant's Work in
                  all events shall include the Building Standard material,
                  hardware and equipment described on, and Tenant shall
                  otherwise comply with, SCHEDULE 1 attached hereto.

         (b)      Tenant agrees to cause its interior space planner (the
                  "Interior Space Planner"), to deliver to Landlord preliminary
                  space plans for the Premises, which preliminary space plans
                  shall include the following information: (1) partition layout;
                  (2) door layout; (3) identification of ceiling types; (4)
                  identification of flooring types;(5) identification of
                  proposed room types and uses; (6) identification of all
                  special floor loading areas and above standard furniture and
                  equipment (files, safes, etc.), along with applicable
                  structural loading information to determine if any structural
                  reinforcing is required; and (7) general information in the
                  form of outline specifications for all proposed millwork,
                  electrical, mechanical, fire protection, communication
                  technology systems and plumbing requirements. Such preliminary
                  space plans are herein referred to as the "Preliminary Space
                  Plans". The Preliminary Space Plans are subject to Landlord's
                  review and approval. Upon receipt of a complete set of the
                  Preliminary Space Plans Landlord will review the same and
                  shall submit specific written comments to Tenant within five
                  (5) business days. Tenant shall cause the Preliminary Space
                  Plans to be revised to incorporate Landlord's comments.

         (c)      Tenant shall deliver to Landlord architectural design
                  development plans and specifications (the "Architectural
                  Design Plans") for the Work to be performed in the Premises.
                  The Architectural Design Plans shall be sufficient in all
                  respects for


                                     B-1
<PAGE>

                  Tenant to cause the mechanical/electrical/communications
                  technology systems engineer, Environmental Systems Design,
                  Inc. (the "Engineer" or "ED") to commence the preparation of
                  the mechanical/electrical/fire protection/plumbing plans and
                  the communications technology design and review (herein
                  referred to as the "MEP/CT Engineering Plans") and without
                  limiting the foregoing shall include the following: (1) all of
                  Landlord's comments to the Preliminary Space Plans; (2)
                  demolition plans; (3) partition plans; (4) reflected ceiling
                  plans; (5) flooring plans; (6) electrical and telephone outlet
                  plans; (7) furniture plans; (8) floor loading plans indicating
                  any special floor loading areas, specific weights for
                  concentrated loads in sufficient detail to allow for
                  structural engineering; (9) computer equipment and support
                  area plans; (10) special area plans (i.e., kitchens, A/V,
                  washrooms, etc.); (11) door, frame and hardware schedules;
                  (12) wall finish plans; (13) elevations, details and sections
                  as required; and (14) specific critical information required
                  by the Engineer to sufficiently engineer the aforesaid
                  Premises. The Architectural Design Plans shall be subject to
                  Landlord's prior written approval. Landlord shall either
                  approve or disapprove the Architectural Design Plans in
                  writing within five (5) days of receipt by Landlord of a
                  complete set thereof. If Landlord does not approve the same,
                  Landlord shall advise Tenant in writing of the specific
                  changes required in such Architectural Design Plans so that
                  they will meet with Landlord's approval. Tenant shall cause
                  the Interior Space Planner to revise the Architectural Design
                  Plans pursuant to Landlord's comments and to deliver to
                  Landlord, within five (5) days after receipt by Tenant of such
                  comments, revised Architectural Design Plans noting the
                  changes for Landlord's approval. Landlord shall continue to
                  comment on such Architectural Design Plans and Tenant shall
                  continue to revise said Architectural Design Plans within
                  seven (7) days of receipt of comments from Landlord until such
                  Architectural Design Plans are approved by Landlord.
                  Notwithstanding anything herein to the contrary, if Tenant
                  elects to use the services of a
                  mechanical/electrical/communication systems design engineer
                  other than ESD, Landlord requires that Tenant submit drawings
                  to Landlord for review and approval by ESD. The cost of such
                  review, along with the cost of updating Landlord's
                  infrastructure documents, shall be borne by Tenant.

         (d)      Tenant agrees to cause the Interior Space Planner and the
                  Engineer to prepare the MEP/CT Engineering Plans for the
                  Premises and deliver said drawings to Landlord. Tenant and the
                  Engineer shall cooperate fully to provide all information
                  necessary for the timely completion of the MEP/CT Engineering
                  Plans and approval thereof by Landlord. Landlord agrees to
                  either approve or disapprove said MEP/CT Engineering Plans in
                  writing within five (5) days of receipt thereof by Landlord.
                  If Landlord disapproves of said MEP/CT Engineering Plans,
                  Landlord agrees to advise Tenant in writing generally of the
                  required changes. Tenant shall deliver to Landlord revised
                  MEP/CT Engineering Plans pursuant to Landlord's comments
                  within five (5) days of receipt of Landlord's comments. This
                  procedure shall be repeated until Landlord approves the MEP/CT
                  Engineering Plans for the Premises.

         (e)      Tenant agrees to cause to be delivered to Landlord fully
                  completed and coordinated Architectural Design Plans and
                  MEP/CT Engineering Plans (the


                                     B-2
<PAGE>

                  "Construction Documents") sufficient in detail so that Tenant
                  can use such revised plans to obtain a building permit and
                  contractors' bids for the Work. The Construction Documents
                  must be in a final and complete form with all necessary design
                  elements identified and specified to fully bid and construct
                  the Work. The Construction Documents are subject to Landlord's
                  review and approval. Landlord shall review the Construction
                  Documents and submit written comments to Tenant within five
                  (5) days of receipt by Landlord of a complete set thereof. If
                  Landlord does not approve the same, Landlord shall advise
                  Tenant in writing generally of the changes required in the
                  Construction Documents so that they meet with Landlord's
                  approval. Tenant shall cause the Construction Documents to be
                  revised until they will meet with Landlord's approval. The
                  Architectural Design Plans, the MEP/CT Engineering Plans and
                  the Construction Documents are herein collectively referred to
                  as the "Plans".

         (f)      Tenant represents to Landlord that Tenant has reviewed its
                  needs and the above specified delivery dates with the Interior
                  Space Planner and that Tenant has assured itself that the
                  Plans can be delivered as herein above required. Tenant agrees
                  to cooperate with the Interior Space Planner as promptly as
                  possible and in any event in sufficient time to cause the
                  Plans to be prepared and timely delivered as herein above
                  required.

         (g)      Neither review nor approval by Landlord of any of the Plans
                  shall constitute a representation or warranty by Landlord that
                  such Plans either (i) are complete or suitable for their
                  intended purpose or (ii) comply with applicable laws,
                  ordinances, codes and regulations, it being expressly agreed
                  by Tenant that Landlord assumes no responsibility or liability
                  whatsoever to Tenant or to any other person or entity for such
                  completeness, suitability or compliance.

2.       COST OF TENANT'S WORK

         (a)      Prior to commencement of any portion of the Tenant's Work,
                  Tenant shall obtain a contract to perform the Tenant's Work by
                  bidding the Tenant's Work to certain of those general
                  contractors from Landlord's list of approved contractors which
                  list is attached hereto as SCHEDULE 2 and made a part hereof.
                  Tenant agrees to promptly give Landlord a copy of the
                  contract. The general contractor must use only those
                  subcontractors on Landlord's list of approved subcontractors
                  set forth on SCHEDULE 3 attached hereto, as the same may be
                  amended by Landlord from time to time.

         (b)      Landlord shall give Tenant a total allowance ("Allowance") of
                  Thirty Five and 00/100 Dollars ($35.00) per square foot of
                  Rentable Area in the Premises as a credit towards the cost of
                  the Tenant's Work including furniture to be installed in the
                  Premises and the cost of Tenant's initial move to the
                  Premises. Tenant shall pay all costs of the Tenant's Work in
                  excess of the Allowance. All amounts shall be paid by Tenant
                  within thirty (30) days after Tenant's receipt of invoices
                  therefor. Tenant agrees that all of the Premises shall be
                  built out to a minimal standard so that at least Thirty and
                  00/100 Dollars ($30.00) per square foot


                                     B-3
<PAGE>

                  multiplied by the number of square feet in that portion of the
                  Premises shall have been expended for "hard costs".

         (c)      Tenant shall pay a construction coordination and overhead fee
                  to Landlord in an amount equal to $.75 per square foot of
                  Rentable Area in the Premises to cover Landlord's
                  coordination, supervision and overhead and related expense
                  allocable to such work (the "Coordination Fee"). The
                  Coordination Fee shall be deducted by Landlord from the
                  Allowance. The Coordination Fee is intended to be all
                  inclusive and includes: (i) the cost of Landlord's preliminary
                  and ongoing review of the Preliminary Space Plans, the Plans,
                  and all other construction documents; (ii) the cost of
                  temporary electricity, temporary toilets, access to phone
                  service and hot and cold water to the Premises during the
                  construction period; (iii) all hoisting charges for reserving
                  and using the Building's freight elevators during normal
                  Building hours for the construction of the Work which use is
                  related to the Tenant's Work and any punchlist items; (iv) the
                  costs of trash removal and disposal (as described in SECTION
                  4(d) hereof); and (v) freight dock services and normal
                  Building security during Tenant's construction and move-in
                  period. Landlord agrees that Tenant shall not be required to
                  pay any sums in addition to the Coordination Fee for other
                  coordination services by Landlord unless such services are
                  requested in writing by Tenant.

         (d)      Landlord shall make payments of the Allowance only one time
                  per month upon receipt of invoices, sworn statements,
                  mechanics lien waivers as provided herein and such other
                  documentation as Landlord may reasonably request. Payment of
                  the Allowance shall be made by Landlord upon Tenant's
                  direction through a construction escrow with the title
                  insurance company selected by Landlord pursuant to escrow
                  instructions reasonably approved by Landlord and Tenant.
                  Landlord shall have no obligation to make any payment of the
                  Allowance at any time that Tenant is in Default hereunder.
                  Landlord shall pay the cost of the escrow.

         (e)      Prior to commencing Tenant's Work, Tenant shall submit to
                  Landlord a total project budget (the "Budget") outlining the
                  cost of the Tenant's Work plus the cost of all non-tenant
                  improvement items, including soft costs, cabling, and
                  telephone to be incurred by Tenant in connection with the
                  Premises (collectively, the "Tenant's Project Costs"). Tenant
                  shall deliver to Landlord an updated Budget with each draw
                  request for a payment of a portion of the Allowance. If, as of
                  the time any such draw request is made, the Tenant's Project
                  Costs pursuant to the current Budget exceed the amount of the
                  Allowance, Tenant shall deposit into the escrow the amount by
                  which the Tenant's Project Costs set forth in the current
                  Budget exceed the remaining amount of the Allowance. All
                  amounts so deposited by Tenant are herein collectively called
                  "Tenant Deposits".

         (f)      Tenant shall make draw requests on the escrow based upon the
                  percentage of Tenant's Project Costs incurred as of the date
                  of the draw request. Tenant shall present to Landlord and to
                  the title company which is acting as escrowee, a letter
                  requesting a disbursement of funds, invoices (or paid receipts
                  for each item paid by Tenant and for which Tenant is seeking
                  reimbursement), a copy of any


                                     B-4
<PAGE>

                  cancelled checks pursuant to which such invoice has been paid,
                  and, with respect to any construction to any portion of the
                  Premises, such lien waivers (for lienable items) required by
                  the title company or Landlord. The lien waiver from the
                  general contractor and from each subcontractor and material
                  supplier must be delivered with each draw request. Landlord
                  shall have no obligation to make a payment until all waivers
                  for the prior draw are submitted.

         (g)      Draw requests shall be submitted to Landlord and the title
                  company not later than the 23rd day of the calendar month. Not
                  later than the 20th day of the next calendar month Landlord
                  will review Tenant's Work and Tenant's draw request and advise
                  Tenant in writing of any respects in which the draw request is
                  disapproved and the reason for such disapproval. Such advice
                  need not comply with the notice provisions of the Lease.
                  Otherwise, the draw request will be deemed approved. Draw
                  requests submitted by the 23rd day of a calendar month shall
                  be paid, subject to the foregoing approval procedure, not
                  later than the 25th day of the following calendar month.
                  Landlord and Tenant agree to cooperate in attempting to
                  resolve disapproved portions of each draw request.

         (h)      Notwithstanding the foregoing, in the event, and only in the
                  event, that on the date that all Tenant's Work and all other
                  non-improvement items have been completed and paid for the sum
                  of the Allowance and any Tenant Deposits exceed the amount
                  disbursed by the escrowee on account of Tenant's Project Costs
                  (the amount of such excess being herein called the "Excess
                  Funds") and provided that Tenant is not then in Default under
                  the Lease, Landlord shall apply such Excess Funds in the
                  following order of priority until such Excess Funds are
                  exhausted:

                  (i)      Landlord shall pay to Tenant, within sixty (60) days
                           following the Commencement Date out of such Excess
                           Funds an amount not to exceed the Tenant Deposits, if
                           any;

                  (ii)     Landlord shall pay, out of any remaining Excess
                           Funds, Tenant Project Costs upon the delivery to
                           Landlord of such bills, invoices, receipts and other
                           supporting documentation as Landlord may reasonably
                           require to evidence Tenant's expenditure of such
                           other Tenant Project Costs; and

                  (iii)    The balance of such Excess Funds, if any, shall be
                           applied as a credit against Base Rent and Additional
                           Rent payable under the Lease beginning with the first
                           full monthly payments of Rent after the partial
                           abatement of Base Rent under SECTION 2(b) of the
                           Lease and the partial abatement of the Tax Adjustment
                           Amount and the Expense Adjustment Amount under
                           SECTION 3(e) of the Lease have all expired.

3.       ACCESS BY TENANT; WORK IN HARMONY.

Tenant agrees for itself and its agents, representatives, employees, suppliers,
contractors, subcontractors, workmen, mechanics, and suppliers, that all such
parties shall work in harmony and not unreasonably interfere with Landlord and
Landlord's agents, representatives, employees, suppliers, contractors,
subcontractors, mechanics, and workmen in doing work for other tenants and
occupants of the Building. Landlord agrees for itself and its agents,
representatives,


                                     B-5
<PAGE>

employees, suppliers, contractors, subcontractors, workmen, mechanics, and
suppliers, that all such parties shall work in harmony and not unreasonably
interfere with Tenant and Tenant's agents, representatives, employees,
suppliers, contractors, subcontractors, mechanics, and workmen in doing the
Tenant Work.

4.       CONSTRUCTION REQUIREMENTS.

         (a)      Tenant agrees that the entry into the Premises by Tenant and
                  its contractors shall be deemed to be under all of the terms,
                  covenants, conditions and provisions of the Lease except as to
                  the covenant to pay Rent, and Tenant further agrees that in
                  connection therewith Landlord shall not be liable in any way
                  for any injury, loss, or damage which may occur to any of
                  Tenant's Work and installations made in the Premises or to
                  property placed therein prior to the Commencement Date and
                  thereafter, the same being at Tenant's sole risk. In addition,
                  Tenant shall require all entities performing work on behalf of
                  Tenant to provide protection for existing improvements to an
                  extent that is satisfactory to Landlord and shall allow
                  Landlord access to the Premises, for inspection purposes, at
                  all times during the period when Tenant is undertaking
                  construction activities therein. If any entity performing work
                  on behalf of Tenant causes any injury to any person or any
                  damage to the Premises, the Building, any other property of
                  Landlord or any other person, then Tenant agrees to indemnify,
                  defend and hold Landlord harmless from any loss, damage or
                  injury suffered in connection with any such damage or injury.
                  Further, Tenant shall cause such damage to be repaired at
                  Tenant's expense and if Tenant fails to cause such damage to
                  be repaired promptly upon Landlord's demand therefor, Landlord
                  may in addition to any other rights or remedies available to
                  Landlord under this Lease or at law or equity cause such
                  damage to be repaired, in which event Tenant shall promptly
                  upon Landlord's demand pay to Landlord the cost of such
                  repairs;

         (b)      All contractors and subcontractors shall use only those
                  service corridors and service entrances designated by Landlord
                  for ingress and egress of personnel and the delivery and
                  removal of equipment and material through or across any common
                  areas of the Building shall only be permitted with the written
                  approval of Landlord and during hours determined by Landlord.
                  Landlord shall have the right to order Tenant or any
                  contractor or subcontractor who violates the above
                  requirements to cease work in the Building and leave the
                  Building and remove its equipment and its employees from the
                  Building and, at Landlord's option restore any portion of the
                  Building on which it has done work to its original condition;

         (c)      As part of the Coordination Fee Landlord shall allow Tenant
                  and Tenant's contractors to have use of the hoist serving the
                  Building during normal operating hours. To the extent Tenant
                  or Tenant's contractors require use of the hoist after normal
                  operating hours Landlord shall use reasonable efforts to
                  accommodate Tenant and the cost thereof shall be determined at
                  Landlord's reasonable discretion. Landlord shall not be
                  required to defer use of the hoist by Landlord or others until
                  after normal operating hours in order to allow use of the
                  hoist by Tenant or Tenant's contractors during normal
                  operating hours. Scheduling of


                                     B-6
<PAGE>

                  Tenant's work in the Premises and the use of said hoist shall
                  be at the reasonable discretion of Landlord or Landlord's
                  contractor;

         (d)      During the performance of Tenant's Work and Tenant's
                  fixturing, Landlord may provide trash removal service from a
                  location designated by Landlord. Tenant shall be responsible
                  for breaking down boxes and placing trash in Landlord's
                  containers at such designated location. Tenant shall
                  accumulate its trash in containers supplied by Landlord and
                  Tenant shall not permit trash to accumulate within the
                  Premises or in the corridors or public areas adjacent to the
                  Premises. Tenant shall cause each entity employed by it to
                  perform work on the Premises to abide by the provisions of
                  this Work Letter as to the storage of trash and shall require
                  each such entity to perform its work in a way that dust or
                  dirt is contained entirely within the Premises and not within
                  any other portion of the Building and shall cause Tenant's
                  contractors to leave the Premises in broom clean condition at
                  the end of each day. Should Landlord deem it necessary to
                  remove Tenant's trash because of accumulation, Tenant shall
                  pay to Landlord an additional reasonable charge for such
                  removal on a time and material basis. The cost to Tenant for
                  Landlord removing such trash will be based on reasonable and
                  competitive cost which Tenant could have secured independently
                  had Landlord not provided such service;

         (e)      Tenant agrees that all services and work performed on the
                  Premises by, on behalf of, or for the account of Tenant,
                  including installation of telephones, carpeting, materials and
                  personal property delivered to the Premises shall be done in a
                  first-class workmanlike manner using only good grades of
                  material and shall be performed only by persons covered by a
                  collective bargaining agreement with the appropriate trade
                  union;

         (f)      Tenant agrees to protect, indemnify, defend and hold Landlord
                  and its agents, partners, contractors and employees harmless
                  from and against any and all losses, damages, liabilities,
                  claims, liens, costs, and expenses, including reasonable
                  attorneys' fees, of whatever nature including those to the
                  person and property of Tenant, its employees, agents,
                  invitees, licensees and others arising out of or in connection
                  with the activities of Tenant or Tenant's contractors in or
                  about the Premises or the Building, and the cost of any
                  repairs to the Premises or the Building necessitated by
                  activities of Tenant or Tenant's contractors;

         (g)      Tenant shall secure, pay for, and maintain during the
                  continuance of its work within the Premises, policies of
                  insurance with such coverages and such amounts as Landlord may
                  reasonably require, which policies shall be endorsed to
                  include Landlord and its contractor and their respective
                  employees and agents and Landlord's mortgagees as additional
                  insured parties and which shall provide thirty (30) days prior
                  written notice of any alteration or termination of coverage,
                  in such amounts and insuring such risks as Landlord may
                  require. Tenant shall not permit Tenant's contractors to
                  commence any work until all required insurance has been
                  obtained by Tenant and certificates evidencing such coverage
                  have been delivered to Landlord; and


                                     B-7
<PAGE>

         (h)      Tenant's agents, subcontractors and vendors shall be required
                  to conform with the "Contractor & Vendor Guidelines" attached
                  hereto as SCHEDULE 4 and made a part hereof.

5.       MISCELLANEOUS.

         (a)      Except as expressly set forth herein, Landlord has no other
                  agreement with Tenant and has no other obligation to do any
                  other work or pay any amounts with respect to the Premises.
                  Any other work in the Premises which may be permitted by
                  Landlord pursuant to the terms and conditions of the Lease
                  shall be done at Tenant's sole cost and expense and in
                  accordance with the terms and conditions of the Lease.

         (b)      This Work Letter shall not be deemed applicable to any
                  additional space added to the original Premises at any time or
                  from time to time, whether by any options under the Lease or
                  otherwise, or to any portion of the original Premises or any
                  additions thereto in the event of a renewal or extension of
                  the initial term of the Lease, whether by any options under
                  the Lease or otherwise, unless expressly so provided in the
                  Lease or any amendment or supplement thereto.

         (c)      The failure by Tenant to pay any monies due Landlord pursuant
                  to this Work Letter within the time period herein stated shall
                  be deemed a Default under the terms of the Lease for which
                  Landlord shall be entitled to exercise all remedies available
                  to Landlord for nonpayment of Rent. All late payments shall
                  bear interest and shall be subject to a late charge pursuant
                  to the Lease.

         (d)      This Work Letter is being executed in conjunction with the
                  Lease and is subject to each and every term and condition
                  thereof, including without limitation, the limitations of
                  Landlord's liability set forth therein.

         (e)      Tenant shall be solely responsible to determine at the site
                  all dimensions of the Premises and the Building which affect
                  any work to be performed by or for Tenant hereunder.


                                     B-8
<PAGE>


Dated this 10th day of March, 2000.

                              LANDLORD:

                              TH TOWER LEASING LLC,
                              a Delaware limited liability company


                              By: /s/ Stephen E. Budorick
                              Its: Vice President


                              TENANT:

                              UNIVERSAL ACCESS, INC.,
                              a Delaware corporation

                              By: /s/ Robert Brown
                              Its: Vice President


                                     B-9
<PAGE>




                                   SCHEDULE 1

                           BUILDING STANDARD MATERIALS
                                   SEARS TOWER

CEILING GRID              -   The ceiling system will be a City of Chicago
                              approved plenum rated, suspended 2' x 2' grid for
                              acoustical lay-in tile, air supply and return will
                              flow through compatible light fixtures with
                              supplemental diffusers as required. The suspended
                              2' x 2' grid will be Chicago Metallic Corp.'s 3500
                              Series in white, Donn Fineline or a similar
                              substitute acceptable to Landlord.

CEILING TILE              -   2' x 2' panels;  "Cirrus  Travertone"  by
                              Armstrong or "Eclipse" by USG Interiors.

TENANT STANDARD           -   Tenant  Standard  Partitions per DeStefano and
PARTITIONS                    Partners  Drawing TN00.2. All core  corridors  to
                              be demised  and all  partitions  above  entryway
                              doors to be demised.  2"stud,  20 gauge,  24" O.C.
                              Floor to underside of deck.  Corridor  side 5/8"
                              sheetrock  and 1/2"  sheetrock.  Tenant side 5/8".
                              Sound batten insulation.

LIGHT FIXTURES            -   2' x 2' or 2' x 4' three fluorescent lamps, air
                              handling, separately fused for 20 AMP circuits,
                              with 18 cell parabolic lens electronic ballasts,
                              T8 lamps and 3500K lamp. 2 x 4 light fixtures to
                              be installed north to south direction.

EXIT & STAIR SIGNAGE      -   ALKO "Edge-glo" Series RPC-210-E-GLR-AP (ceiling
                              mounted).

SPRINKLER HEADS           -   Phantom 1, Model PH-1 concealed sprinkler with
                              flush cover plate, bright chrome, by Grunau
                              Sprinkler Manufacturing Co. or Model G1 concealed
                              sprinkler with flush cover plate, bright chrome,
                              by Reliable Automatic Sprinkler Co., Inc.  Note:
                              Flush covers are required.


VINYL COMPOSITION TILE

         1.       Composition 1 - Asbestos-Free
         2.       Class 2 (Through Pattern)
         3.       Gage: 1/8"
         4.       Wearing Surface:  Smooth

CARPETING                 -   Broadloom  tackless  with pad or carpet  tiles.
                              Note:  Direct glue down is not allowed.

WINDOW BLINDS             -   Thin slat  horizontal  blinds.  Perimeter  window
                              blinds  furnished and installed by building.

DOORS                     -   Full height, solid core (refer to Chicago code for
                              fire rating).


                                      1
<PAGE>

HARDWARE                  -   A.       Schlage lever handle,  L-series 01A625 on
                              public corridor doors and  Schlage compatible
                              hardware on all other doors.

                              B.       Hinges - Stanley or Hager,  in anodized
                              bronze finish,  2 pair per leaf, 4" x 4 1/2".

PUBLIC ADDRESS SYSTEM     -   Existing building emergency public address
                              speakers must be replaced to match base building
                              standard type: Wheelock ET-1080W. Existing speaker
                              wiring to be zoned throughout floor for building
                              standard speaker diffusion by tenant.

PRIVATE WASHROOMS         -   Private washrooms must have floor drains.

THERMOSTATS               -   One thermostat per bay for induction units
                             (optional).

VAV/DDC                   -   All new construction and remodeling must have VAV
                              boxes/DDC control. 1 box per useable 1600 sq. ft.

OPEN SITE DRAINS          -   Open site drains for Package A/C units are to be
                              installed at floor level or under sink cabinets.
                              Open site drains in plenum ceiling are prohibited.

CAD DRAWINGS              -   All architectural and MEP drawings must be
                              produced on CAD.

FLOOR MOUNTED A/C UNITS   -   All new floor mounted A/C units must have a floor
                              drain.

ACCESS PANELS             -   If broadloom carpet is specified, the architect
                              make provisions for future access to the under
                              floor cell system hand holes and all utilized
                              cells.

ELEVATOR LOBBIES          -   The design must account for code compliant egress
                              out of the passenger and freight elevator lobbies
                              at all times with access to a minimum of one exit
                              stairwell. The Tenant's security concerns should
                              be evaluated with respect to this requirement.

STONE INSTALLATIONS       -   If stone flooring is specified, please coordinate
                              the stone installation so that there is no
                              tripping hazard at the elevator sills due to
                              elevation differences.

CECO DOORS                -   The existing CECO doors on floors cannot be
                              disturbed. Only a decorative surface can be
                              applied to these doors with Landlord approval and
                              supervision. Modifications to core doors, frames
                              and hardware are prohibited.

INDUCTION UNIT AIR FLOW   -   Please design any fixed drywall partitioning,
                              furniture system, and equipment a minimum of 12" -
                              18' away and a minimum of 4" up from floor from
                              the induction units to allow for proper air flow
                              through and access to the units for building
                              maintenance and window washing.


                                    2
<PAGE>

                                   SCHEDULE 2

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------
                                   SEARS TOWER
----------------------------------------------------------------------------------------------------------------------------------
                          APPROVED GENERAL CONTRACTORS
----------------------------------------------------------------------------------------------------------------------------------
CONTRACTOR                                CONTACT                              PHONE #                  FAX #
----------------------------------------- ------------------------------------ ------------------------ --------------------------
<S>                                       <C>                                  <C>                      <C>
Clune Construction                        Chris Redath                         (312) 726-6103           (630) 419-8139
10 S. LaSalle Street, Suite 300
Chicago, IL  60603
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Exclusive Construction Services           Mike Rosner                          (630) 257-8527           (630) 257-8527
1224 133rd Court
Lemont, IL  60439
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Executive Construction Co.                James Pierzchalski                   (630) 472-5817           (630) 472-5858
2122 York Road, Suite 360
Chicago, IL  60523
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Fredrickson KRJ                           Don Haton                            (312) 875-9244           (312) 875-2166
233 S. Wacker, Suite 570
Chicago, IL  60606
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Interior Construction Group               Steve Zuwala                         (312) 553-4949           (312) 553-0649
230 West Monroe, Suite 2530
Chicago, IL  60606
----------------------------------------- ------------------------------------ ------------------------ --------------------------
JC Anderson                               David Goss                           (630) 834-1669           (630) 834-0142
245 Sydney Court
Villa Park, IL  60181
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Krahl Construction                        Doug Harner                          (312) 648-9800           (312) 648-4610
223 West Jackson
Chicago, IL  60606
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Leonard Companies, Inc.                   Rick DuPraw                          (312) 329-9556           (312) 329-9790
333 West Wacker Drive, Suite 250
Chicago, IL  60606
----------------------------------------- ------------------------------------ ------------------------ --------------------------
The Meyne Company                         Mark Evans                           (312) 207-2100           (312) 207-0488
1755 West Armitage Avenue
Chicago, IL  60610
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Pepper Construction Co.                   David Pepper                         (312) 266-4700           (312) 266-2792
643 North Orleans
Chicago, IL  60610
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Reed Illinois Corporation                 Joseph Bekken                        (312) 943-8100           (312) 943-8141
930 West Division Street
Chicago, IL  60622
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Turner Construction Co.                   Tom Wichlinski                       (312) 704-0770           (312) 704-0563
11 South LaSalle Street, Suite 1800
Chicago, IL  60603
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Victor Construction Co.                   Greg Kolinski                        (312) 944-6901           $312) 944-6927
950 North Michigan Avenue, Suite 1275
Chicago, IL  60611
----------------------------------------- ------------------------------------ ------------------------ --------------------------
Walsh Construction                        Steve Downey                         (312) 563-5400           (312) 563-5467
929 West Adams
Chicago, IL  60607
----------------------------------------- ------------------------------------ ------------------------ --------------------------
</TABLE>


<PAGE>

                                   SCHEDULE 3

                                                                   Revised 11/99

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                   SEARS TOWER

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

                          APPROVED PLUMBING CONTRACTORS

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

CONTRACTORS                            CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Great Lakes Plumbing & Heating         Gene Hyken                            (312) 876-0813            (312) 876-1932
4521 West Diversey
Chicago, IL  60639
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Johns Plumbing                         Mike Shudy                            (773) 286-9030            (773) 286-5073
3116 North Cicero
Chicago, IL  60641
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Pientka Plumbing                       Bob Klauk                             (847) 296-3326            (847) 296-3321
10 West Kathleen
Des Plaines, IL  60016
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>


<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                   SEARS TOWER

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

                          APPROVED HVAC SUB-CONTRACTORS

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

CONTRACTORS                            CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Anchor Mechanical                      Noel Daly                             (312) 492-6994            (312) 492-6996
600 West Jackson Blvd.
Suite 150
Chicago, IL  60661
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
James Anderson, Inc.                   Thad Bednarz                          (708) 345-2400            (708) 343-0581
2030 Janice Ave.
Melrose Park, IL  60160
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Climatemp                              Frank Senese                          (312) 829-3131            (312) 829-7510
315 North May
Chicago, IL  60607
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Hill Mechanical Group                  Warren Hill                           (773) 929-6600            (773) 929-9549
4241 Ravenswood
Chicago, IL  60613
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Midwest Mechanical                     Ron Hill                              (630) 655-4200            (630) 655-0730
540 Executive Drive
Willowbrook, IL  60521
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Talmar Metal Products                  Ed Slowinski                          (708) 280-0461            (708) 693-3106
7703 West 98th Street
Hickory Hills, IL  60457
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Thermflo                               Kevin O'Brian                         (847) 541-0029            (847) 541-0272
251 Holbrook Drive
Wheeling, IL  60090
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>

<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                   SEARS TOWER

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

                     APPROVED TELECOMMUNICATIONS CONTRACTORS

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

CONTRACTOR                             CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Continental Electric                   Joel Johnson                          (847) 677-1600            (847) 677-1668
5900 West Howard
Skokie, IL  60077
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Maron Electric Co.                     Allen Kazamie                         (847) 679-6500            (847) 679-6503
5401 West Fargo Avenue
Skokie, IL  60077
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Prime Electric                         Mike Magee                            (312) 433-9111            (312) 433-6493
215 South Aberdeen
Chicago, IL  60601
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Shamrock Electric Co.                  Lee Mattson                           (312) 876-2970            (312) 876-3908
1281 East Brummel
Elk Grove, IL  60007
-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>

<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                                           SEARS TOWER

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

                                               APPROVED ELECTRICAL SUB-CONTRACTORS

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

CONTRACTOR                             CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Commercial Light Co.                   Scott Morris                          (708) 449-6900            (708) 449-6942
245 Fencl Lane
Hillside, IL  60162

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Continental Electric                   Joel Johnson                          (847) 677-1600            (847) 677-1668
5900 W. Howard
Skokie, IL  60077

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
J.W. O'Brien Corp.                     Jack O'Brien                          (847) 965-7780            (847) 965-7796
6314 Lincoln Ave.
Morton Grove, IL  60053

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Maron Electric Company                 Allen Kazamie                         (847) 679-6500            (847) 679-6503
5401 W. Fargo Avenue
Skokie, IL  60077

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Prime Electric                         Mike Magee                            (312) 433-9111            (312) 433-6493
215 South Aberdeen
Chicago, IL  60601

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Shamrock Electric Co.                  Lee Mattson                           (312) 876-2970            (312) 876-3908
1281 E. Brummel
Elk Grove Village, IL  60007

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Palos Electric Company, Inc.           Brian Crehan                          (312) 251-1368            (312) 251-1435
4630 West 138th Street
Crestwood, IL  60445

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>
<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                                           SEARS TOWER

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

                                    APPROVED FIRE, LIFE SAFETY CONTROLS, SECURITY SUB-CONTRACTORS

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

                                                 FIRE, LIFE SAFETY CONTROLS, SECURITY

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

CONTRACTOR                             CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Advent Systems Inc.                    John Lothrop                          (630) 279-7171            (630) 279-7676
477 W. Wrightwood Ave.
Elmhurst, IL  60126

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Chicago Communication Systems          Luis Marrero                          (847) 956-8500            (847) 956-1593
1699 Elmhurst Road
Elk Grove, Illinois  60007

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Electronic Systems USA, Inc.           Mark Eggerding                        (708) 449-3334            (708) 449-3454
4413 Roosevelt Rd.,  110-B
Hillside, IL  60162

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Sentry Fire Protection Systems         Mary McDonnell                        (773) 489-6700            (773) 489-1197
1322 West North Avenue
Chicago, IL  60622

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

Note:  ESUSA must make ALL final terminations to Base Building System.


----------------------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                                           SEARS TOWER

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

                                          APPROVED TEMPERATURE CONTROL SUB-CONTRACTORS
----------------------------------------------------------------------------------------------------------------------------------

                                                      TEMPERATURE CONTROLS

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

CONTRACTOR                             CONTACT                               PHONE #                   FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Advent Systems Inc.                    John Lothrop                          (630) 279-7171            (630) 279-7676
477 W. Wrightwood Ave.
Elmhurst, IL  60126

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Electronic Systems USA, Inc.           Mark Eggerding                        (708) 449-3334            (708) 449-3454
4413 Roosevelt Road
Suite 110-B
Hillside, IL  60162

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Johnson Controls                       Joel Lehman                           (847) 364-1500            (847) 364-1536
3007 Malmo Drive
Arlington Heights, IL  60005

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Landis & Gyr Powers                    John Dwan                             1-800-339-7800            (847) 499-3454
5440 W. Fargo
Skokie, IL  60077

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Thermflo                               Kevin O'Brian                         (847) 541-0029            (847) 541-0272
251 Holbrook Drive
Wheeling, IL  60090

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>
<PAGE>

                                                                   Revised 11/99
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------

                                                           SEARS TOWER

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

                                         APPROVED SPRINKLER/PIPE FITTER SUB-CONTRACTORS

----------------------------------------------------------------------------------------------------------------------------------
CONTRACTOR                             CONTACT                               TELEPHONE #               FAX #

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
<S>                                    <C>                                   <C>                       <C>
Ewing-Doherty Mechanical               Doug Ewing                            (630) 766-5920            (630) 766-0734
304 North York Road
Bensenville, IL  60101

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Great Lakes Plumbing & Heating         Gene Hyken                            (312) 876-0813            (312) 876-1932
4521 W. Diversey
Chicago, IL  60639

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
Superior Mechanical Systems            Patrick Sullivan                      (708) 599-5008            (708) 599-5017
7738 West 99th Street
Hickory Hills, IL  60457

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
U.S. Fire Protection                   Mike Peterson                         (847) 816-0050            (847) 816-0098
28427 N. Ballard Drive
Lake Forest, IL  60045

-------------------------------------- ------------------------------------- ------------------------- ---------------------------
</TABLE>
<PAGE>

                                   SCHEDULE 4

                         CONTRACTOR & VENDOR GUIDELINES



                                     For the

                                   SEARS TOWER








                       TRIZECHAHN OFFICE PROPERTIES, INC.
                                November 1, 1999
<PAGE>

                                   SEARS TOWER
                                PROJECT DIRECTORY
<TABLE>
<CAPTION>
DIRECTORS                  TITLE                                                                   PHONE
---------                  -----                                                                   -----
<S>                        <C>                                                                   <C>
Alex Pappas                Director of Design & Construction.....................................875-3643
Tom Keaty                  Director of Operations................................................875-0492
Liz Iozzo                  Assistant to Directors of Operation, Design & Construction ...........875-9763

MANAGERS
--------

George Rumel               General Manager.......................................................875-9463
Peg Kelley                 Assistant to General Manager..........................................875-9463
Steve Budorick             Senior Vice President ................................................875-1848
Jocelyn Mousel             Assistant to Senior Vice Preisdent....................................875-1848

SECURITY
--------

Carlos Villarreal          Director of Security..................................................875-8817
Peg Kelley                 Insurance (Certificates of Insurance).................................875-9463
Debbie Vrtis               Command Center Supervisor.............................................875-0170
Mark Swiecionis            Fire & Life Safety Officer............................................875-0070
SECURITY CONSOLE                    .............................................................875-7711

TENANT SERVICES
---------------

Jill Piunti                Tenant Advocate.......................................................875-8785
Ashley Buchanan            Assistant Manager, Tenant Services....................................875-6785
Calysta Johnson            Assistant to Tenant Services..........................................875-6433

ENGINEERING
-----------

Tom Cronin                 Chief Engineer........................................................875-0491
Bob Edwards                Assistant Chief.......................................................875-0490
Mark Boswell               Assistant Chief.......................................................875-0493

EMERGENCY NUMBER                    .............................................................875-7711

BUILDING SERVICES
-----------------

Security Command Center               (24 Hours a day)...........................................875-7711
Engineering Control Room              (24 Hours a day)...........................................875-0488
Office of the Building                (7:30 am. - 5:30 pm. Mon. - Fri.)..........................875-0066
Shipping/Receiving                    (7:30 am. - 3:30 pm.)......................................875-0063
Fire & Safety Officer                 (24 Hours a day)...........................................875-0070
Dave Brumirski                        Locksmith..................................................875-0076


                                       1
<PAGE>

BUILDING HOURS OF OPERATION
---------------------------

Building Business Hours:            Monday - Friday..............................8:00 am - 6:00 pm
                  After Hours:      Monday - Friday..............................6:00 pm - 8:00 am
                                    Saturday, Sunday and Holidays.........................24 hours

Loading Dock Hours:                 Monday - Friday..............................5:00 am - 3:30 pm
                                    Saturday....................................7:00 am - 12:00 pm
                                    Sunday and Holidays.....................................CLOSED
Freight Service Hours:
                                    Monday - Friday..............................5:30 am - 3:30 pm
                                    Saturday....................................7:00 am - 12:00 pm
                                    Sunday and Holidays.....................................CLOSED

BUILDING HOLIDAYS
-----------------

New Years Day                       Memorial Day                Independence Day
Labor Day                           Thanksgiving Day             Christmas Day
</TABLE>

                                       2
<PAGE>

                                   SEARS TOWER

                         CONTRACTOR & VENDOR GUIDELINES

These guidelines have been developed by building management of Sears Tower to
provide information regarding procedures in the building. The purpose being to
facilitate the completion of projects in a timely and safe manner.

Cooperation is essential and although not all possible situations can be
foreseen, these guidelines deal with general areas of concern. Should any issue,
not dealt with herein arise, contact building management in the Office of the
Building during regular business hours or the Security Command Center after
hours.

It is expected that the contractor will abide by all legal City of Chicago
building codes, OSHA, NFPA, and EPA guidelines.

Security for the construction area during construction work is the
responsibility of the contractor. This extends to possessions as well as the
securing of the area upon completion of the work period. All temporary locking
devices are to be provided by the building locksmith.

We expect a contractor working in our building to realize that he and his
employees are invited guests and will be expected to exercise good judgment and
courtesy at all times. Furthermore, be aware that many other businesses are
operating within the building simultaneously and building management is
committed to providing them with a QUIET, CLEAN, AND SAFE ENVIRONMENT.

MANAGEMENT RESERVES THE RIGHT TO HALT OR DELAY ANY WORK IN THE BUILDING IF WE
DETERMINE THAT THE WORK INTERFERES WITH OUR TENANT'S ABILITY TO REASONABLY
CONDUCT THEIR BUSINESS. ALL LOUD NOISE RELATED WORK SHALL BE COMPLETED PRIOR TO
7:30 A.M. OR AFTER 6:00 P.M. Any and all work that results in noise affecting
areas in the building other than the floor under construction, including but not
limited to concrete coring or sawing, hammering, drilling, SHOOTING OF CEILING
HANGERS, cutting of pipes along the columns or within the concrete slab, SHALL
BE DONE AFTER REGULAR BUSINESS HOURS OR ON WEEKENDS, or with the prior
permission of the building Project Manager. Security measures will be taken if
required to assure compliance.

When after-hours work is required, building management and the Director of
Security must be notified no later than the close of business on the preceding
business day. Also, arrangements must be made at this time for freight elevator
or rubbish removal service. See Contractor After Hours Building Access
Authorization Form.

Prior to the start of work, the General Contractor must submit the permit,
insurance certificates and the names and addresses of all subcontractors,
together with the name and telephone number of a contact person for each
subcontractor to the building Project Manager. Also, the General Contractor must
introduce the job superintendent to the Project Manager, Chief Engineer,
Director of Security and Freight & Dock Services Master. See Project Information
Sheet.


                                      3
<PAGE>

INSURANCE REQUIREMENTS

The General Contractor, EACH subcontractor, architect, interior space planner,
and all of the Tenant's contractors and vendors must submit to the building
Project Manager, before the start of work, a current certificate of insurance
naming the Owner of the Building, its leasing agent and its mortgage lenders as
additional insureds in the following manner:

1.      The name and address of the CERTIFICATE HOLDER:

         TH TOWER LEASING LLC & PARTNERS TOWER, L.P. (OWNER)
         c/o TrizecHahn Office Properties, Inc.
         Attention:  Insurance Records Administrator
         233 South Wacker Drive, Suite 3330
         Chicago, Illinois  60606

2.       Your Certificate must correctly list the ADDITIONAL INSURED parties.
         The following should be covered as additionally insured parties with
         respect to general liability coverage:

         TRIZECHAHN OFFICE PROPERTIES, INC. (MANAGING AGENT)
         233 South Wacker Drive, Suite 3330
         Chicago, Illinois  60606

         TH TOWER LEASING LLC, PARTNERS TOWER, L.P., ATTORNEY FOR STATE STREET
         BANK & TRUST COMPANY, (OWNER), TRUSTEE UNDER A GRANTOR TRUST AGREEMENT
         DATED AS OF OCTOBER 31, 1994, AND KNOWN AS THE 233 SOUTH WACKER DRIVE
         TRUST

         c/o TrizecHahn Office Properties, Inc.
         233 South Wacker Drive, Suite 4600
         Chicago, Illinois  60606
         Attention Vice President

         METROPOLITAN LIFE INSURANCE COMPANY (MORTGAGE HOLDER)
         2001 Spring Road, Suite 400____________________________________________
         Oak Brook, Illinois  60521
         Attention:  Investment Officer - MPSAR


                                      4
<PAGE>

PLEASE MAIL THE CERTIFICATE TO:

                       TRIZECHAHN OFFICE PROPERTIES, INC.
                   ATTENTION: INSURANCE RECORDS ADMINISTRATOR
                          233 SOUTH WACKER DRIVE, #3330
                                CHICAGO, IL 60606

Certificates should state the following limits of coverage:

1.       Statutory Worker's Compensation for the General Contractor and each
         Subcontractor and Vendor and the Architect/Interior Space Planner.

2.       General Commercial Liability in the Amount of not less than $5 Million
         per occurrence for the General Contractor and $1 Million per occurrence
         for EACH Subcontractor, Vendor and the Architect/Interior Space Planner
         (Combined Single Limit for Bodily Injury and Property Damage).

3.       Automobile Liability in the Amount of not less than $3 Million for the
         General Contractor and $1 Million for EACH Subcontractor, Vendor and
         the Architect/Interior Space Planner (Combined Single Limit for Bodily
         Injury and Property Damage).

                  Medical Expenses - $5,000 per person per accident
                  Uninsured/Underinsured Motorists' Coverage - $1,000,000
                  Excess Liability Coverage - $5,000,000

4.       The General Contractor and EACH Subcontractor, Vendor and the
         Architect/Interior Space Planner must maintain Employer's Liability
         Insurance in the Amount of not less than $500,000 per accident and per
         disease, per employee.

5.       The General Contractor must maintain Owner's and Contractor's
         Protective Insurance in the Amount of NOT LESS THAN $5 Million per
         occurrence, and NOT LESS THAN $10 million per occurrence for any work
         associated on the exterior of the building (i.e., roofs, antennas or
         curtainwall work).

6.       The Architect/Interior Space Planner must maintain Professional
         Liability Insurance in the Amount of NOT LESS THAN $1 Million for
         projects costing less than $10 Million and NOT LESS THAN $2 Million for
         projects costing $10 Million or more.

Total Per Occurrence/Accident Limits for Commercial General Liability, Auto
Liability and Employer's Liability Insurance may be satisfied by a party with
any combination of primary and excess or umbrella liability policies totaling
the amount of the required insurance.

The General Contractor is responsible for coordinating ALL insurance
certificates for all subcontractors and vendors prior to mobilization and before
any work will be allowed to commence on site.


                                      5
<PAGE>

It is the intention of the Building Ownership that each lease and each
construction contract and subcontract contain a MUTUAL WAIVER OF SUBROGATION so
that the parties thereto eliminate any law right of subrogation of, or the right
to assign, by way of subrogation, to any insurance company carrying insurance
policies on any portion of the building and its contents, any cause of action
which any party to a lease or construction contract or subcontract may have
against the other party to such subcontract, contract or lease because of
negligence or other wrongful conduct as a cause for any loss which is thus
insured.

Inasmuch as the mutual waivers contained in the leases and construction
contracts and subcontracts will preclude the assignment of any aforesaid claim
by way of subrogation (or otherwise) to an insurance company (or any other
party), each party providing insurance under a lease or a construction contract
or subcontract must agree to cause each insurance company which has issued to it
policies of insurance, to consent to such waiver and to waive all rights of
subrogation against the parties named as additional insureds above.

TRADES PERSONS RULES

1.       UNIONS - All trades persons are to have the proper trade union or other
         affiliations as required by the local jurisdictional entities.

2.       ELEVATORS - TRADES PERSONS WILL USE FREIGHTS FOR ACCESS TO CONSTRUCTION
         FLOORS. Building management reserves the right to monitor and require
         specific rules for the use of elevators if it so warrants or to limit
         the use of the elevators if the privilege is abused.

3.       SECURITY IDENTIFICATION - All trades persons are to have Building
         Identification Cards. All General Contractor supervisors working on the
         project must display a building photo I.D. badge. (PICTURES ARE TAKEN
         MONDAY-FRIDAY, FROM 10AM-11AM AT THE TOWER HEALTH CLUB, LOCATED ON LL3
         OF THE SEARS TOWER). All other contractor employees and subcontractors
         working on the project must be issued a contractor ID pass. (see
         Contractor I.D. Authorization Form). This will allow them access into
         the building Monday-Friday, from 6am-6pm. Any required dock passes will
         also be issued at this time. The building I.D. badges are to be visibly
         worn at all times when within the building. The General Contractor will
         be responsible for any I.D. badges not returned upon completion of the
         project. Building security will monitor all trades persons. Building
         management reserves the right to interrupt any work in the building if
         any Contract Vendor Guidelines are not followed and the General
         Contractor will be responsible for delays caused as a result thereof.
         Please refer to the Contractor I.D. Authorization Form for further
         instructions on obtaining I.D.s.

4.       PUBLIC AREAS - The building does not permit anyone to loiter in public
         areas of the building and construction personnel may not loiter in the
         areas of the building where they are not working.

CONSTRUCTION DOCUMENTS & SPECIFICATIONS


                                      6
<PAGE>

No work will be allowed to proceed without Building Management first reviewing
the most current set of drawings outlining the scope of work. If the building
Project Manager requires the services of outside consultants, i.e., a structural
engineer to review load or coring requirements, the cost of such review will be
the responsibility of the contractor and/or tenant for whom the job is being
performed.

PERMITS

The following is required by the General Contractor prior to the start of
construction or the delivery of materials:

- A copy of the building permit must be posted at the job site;

- THE ORIGINAL BUILDING PERMIT must be kept on file in the management office of
the building, immediately upon receipt from the City of Chicago.

RUBBISH REMOVAL

The General Contractor will be responsible for bringing all rubbish to the
loading dock and placing it into a designated dumpster box. Scheduling for
freight elevator time required and dumpster box pick up and delivery is to be
coordinated by the General Contractor with the Director of Security.

ALL FOOD WASTE AND ANY OTHER DEBRIS THAT MAY CAUSE SAFETY HAZARDS, ODORS, OR ANY
OTHER BUILDING PROBLEM MUST BE REMOVED ON A DAILY BASIS.

Effective January 1, 1999, the Sears Tower will be issuing punch coupons for use
of building dumpsters at the loading dock.

Each coupon card will contain 25 punches to be used when dumping construction
debris into a dumpster at the Sears Tower loading dock. Each gondola, flat
truck, or "A" frame dolly brought to the loading dock will require one punch
from the coupon card.

If you are performing a remodeling project directly for an existing tenant of
the building, not in connection with a TrizecHahn contract or a new lease,
coupon cards must be purchased in advance by the contractor. The cost of each
card is $375 and contains 25 punches. (COST FOR ONE SQUARE YARD OF WASTE IS
EQUAL TO $15.00.)

If you are performing new construction and your contract is directly with
TrizecHahn, you must pick up coupon cards in advance.

All coupon cards will be issued directly to the contractor by the building
management for each project.

When dumping debris on the loading dock, a coupon card must be presented to the
Dock Manager (approx. one square yard of waste) for each gondola, "A" frame, or
flat truck load to be disposed.


                                      7
<PAGE>

Enclosed is an order form for your coupon cards. You must order your cards two
(2) weeks in advance. Please contact the Project manager should you have any
questions.

PREMIUM TIME SERVICE

The building will keep separate work tickets for the premium hours performed as
specifically requested. The premium time rate for personnel will be billed to
the tenant and/or contractor.

Note that there is a minimum charge of four (4) hours for each request of
premium time. This service should be scheduled a minimum of 48 hours, in
advance, with the Office of the Building.

FREIGHT ELEVATORS

The freight elevators are controlled by key card readers, which can be operated
by authorized key cards only or an operator, supplied by the building.
Scheduling should be arranged a minimum of 24 hours in advance with the Director
of Security.

FREIGHT CAR SIZES, CAPACITIES AND SPEEDS ARE LISTED BELOW:

<TABLE>
<CAPTION>
                                         Low         Tall        Outer         Outer
    Freight Car   Width      Length      Height      Height      Door Ht.      Door Wd.         Capacity       Elev.speed
    -----------   -----      ------      ------      ------      --------      --------         --------       -----------
    <S>           <C>        <C>         <C>         <C>         <C>           <C>              <C>            <C>
    F1            7'3"       6'1"        12'         15'7"       8'1"          4'               4000 lb.        @ 1200 fpm

         (Serves Floors:  LL3 - Lobby, 3, 31, 64, 66 - 102)

    F2            7'11"      6'7"        12'         15'7"       8'9"          5'8"             5000 lb.        @ 1000 fpm

         (Serves Floors:  LL3 - Rest 2, 33 - 63)

    F3            11'9"      7'6"        12'         15'7"       8'9"          7'11"           10000 lb.        @ 1200 fpm

         (Serves Floors:  LL1 - 102)

    F4            7'10"      6'7"        12'         15'7"       8'9"          5'9"             5000 lb.        @ 1000 fpm

         (Serves Floors:  LL1, 33 - 63)

    F5            7'11"      6'7"        12'         15'7"       8'9"          5'8"             5000 lb.        @ 1000 fpm

         (Serves Floors:  LL2 - Lobby, 3, 4 - 31, 63)

    F6            7'11"      6'7"        12'         15'7"       8'9"          5'8"             5000 lb.        @ 1000 fpm

         (Serves Floors:  LL1, 4 - 28, 63)
</TABLE>

Note: Special hoisting of oversized and/or heavy items must be done by building
elevator personnel. Coordination must be made through the building Project
Manager.


                                      8
<PAGE>

FREIGHT ELEVATOR LOBBY (TYPICAL FLOORS)

The design and construction phase must account for code compliant egress out of
the passenger and freight elevator lobbies at all times with access to a minimum
of one exit stairwell. The Tenant's security concerns should be evaluated with
respect to this requirement. (Maximum floor load is 75 lbs. per sq. ft. in
typical freight lobby).

THIS MEANS KEEP THE FREIGHT LOBBIES CLEAR OF ALL DEBRIS!

LOADING DOCK

All materials shall be brought into the building at the loading dock which is
located one level below grade and is accessible from Lower Wacker Drive or
freight elevators. All deliveries will be required to be scheduled and
coordinated with the Assistant Director of Security. The height restriction for
Lower Wacker Drive is 12'6". Trailer length restriction is 40'. A 48' maximum
trailer length may be accommodated during off hours only.

SITE SECURITY

The General Contractor is responsible for the security of the project site for
the duration of the work. Building security must have access to the site at all
times. The General Contractor is responsible to insure that building security
has the proper keys necessary for ALL such access.

HAZARDOUS MATERIAL STORAGE

All hazardous material must be properly stored on the job site. The location of
the stored hazardous material MUST BE listed and supplied to the building
Project Manager AND the Fire & Life Safety Officer. (In case of a fire, the
location of such material must be immediately available)

A list of all hazardous materials as well as copies of all MSDS sheets must be
supplied to the building Project Manager and Fire & Life Safety Officer.

WINDOWS/SOLAR WINDOW FILM

Building windows and solar window film must be protected during the construction
process. A site survey of the building windows will be performed both before and
at the conclusion of the project. Any damage not noted during the initial
walkthru will be the responsibility of the General Contractor at the end of the
construction. Any solar window film repair costs will be charged to the Tenant
or the General Contractor.

If there are any questions regarding the windows or window film, contact the
building Project Manager.

CARPETING


                                      9
<PAGE>

Both broadloom and carpet tiles are approved for installation at the Sears
Tower. Carpet glued down directly onto the concrete slab is NOT allowed. In the
case of broadloom carpet, tackless strip installation must be scheduled for
either before or after regular business hours or on a weekend.

No permanent glued down carpet is acceptable and will be rejected.

All carpeting should be delivered to the loading dock and taken to the location
of installation within the building upon delivery. Old carpet must be disposed
of by the carpet installer or the General Contractor.

The cost to repair or repaint a wall or walls damaged as a result of carpet
installation will be the responsibility of the carpet installer or the General
Contractor.

HVAC

The perimeter induction units must be clean at job completion and inspected by
the building Chief Engineer.

Any HVAC test and air balance reports are to be submitted to the building
Project Manager upon completion of work. To be forwarded to the Director of
Mechanical Operations for review.

FIRE PROTECTION SPRINKLERS

Modifications must comply with the plans approved by the building Director of
Mechanical Operations. Before any work may begin, the contractor must first
check in with the Chief Engineer who will isolate the floor on which the work
takes place.

All fire protection system work that is started on a given day must be completed
by 3:00 p.m. on the same day. The General Contractor is responsible for
coordinating this activity.

All penetrations are to be sealed with approved fire rated material.

No welding or any other work that has the potential of activating the building
fire/smoke detection system or has the potential of attracting outside attention
may commence without first informing the Chief Engineer/Engineering Control Room
and the Fire & Life Safety Officer/Security Command Center. It is MANDATORY that
welding, torching, and soldering permits be obtained from building security
prior to the start of work. Upon completion of the work, it is mandatory that
the Security Command Center and Engineering Control Room be notified. Contact
can be made with those listed below:

SECURITY COMMAND CENTER.............................................. ..875-7711
ENGINEERING CONTROL ROOM................................................875-0488
TRIZECHAHN/OFFICE OF THE BUILDING.......................................875-0066
FIRE & LIFE SAFETY OFFICER..............................................875-0070


                                      10
<PAGE>

Permits will be issued through the Fire & Life Safety Officer, or in an after
hours emergency through the security shift supervisor on duty. Please supply the
following information:

A.       Your company name
B.       Nature of the job, i.e., welding, sweating water lines, etc.
C.       The firm, floor, and specific location of the work area
D.       The approximate time involved, start to finish

No work shall be performed if a welding/cutting permit has not been issued by a
building security department representative. The General Contractor is
responsible for fire safety including providing watchman and extinguishers
during construction.

PLUMBING

Before any plumbing shutdowns may begin, the contractor must first check in with
the Chief Engineer. The General Contractor is responsible for coordinating the
activity. Futures (for future work) must be provided at wet columns, vent, and
drainage systems.

ACCESSIBILITY

All new or existing MEP items, whether behind walls or above ceilings, which
require maintenance must remain accessible at the completion of the project.

HOT TAPS

Hot taps are to be pressure tested prior to doing actual hot tap, and be checked
by the building engineer.

ELECTRICAL

A.       Panelboards shall be braced and rated for a minimum (10,000 AMP
         Interrupt Capacity A.I.C.) with copper buss only.

B.       Circuit breakers for panelboards shall be of the bolt on type, rated
         for switching duty and rated for minimum (10,000 A.I.C.) and are to be
         clearly marked with regard to use on the inside door of breaker panel.

C.       Branch circuit breakers of 2P and 3P configuration shall have a common
         trip.

D.       Wire and cable to be copper and minimum size wire to be #12 except for
         control wire.

E.       Thin wall fittings shall be steel compression type.

F.       Wire is to be installed in conduit unless otherwise approved.

G.       Existing wiring and/or conduit and any temporary wiring, existing or
         added, that is not to be reused shall be removed prior to the
         completion of the project.


                                      11
<PAGE>

H.       Emergency lights and exit sign wiring shall be separate conduit
         systems.

I.       City of Chicago plenum approved Flex must be used for installation of
         all new or relocated light fixtures.

J.       Electrical and telephone (if involved) closets are to be cleaned at
         completion of work. All penetrations to be sealed equal to fire wall
         rating. Panel directories are to be updated and inserted in panel door
         with a copy submitted to building Project Manager.

AS-BUILT DRAWINGS

All mechanical trades are required to submit copies of as-built drawings to the
General Contractor. The General Contractor will make one submission of three
copies of as-built drawings for all trades to the building Project Manager. All
as-built drawings are to be dated and signed by the appropriate subcontractor as
well as the General Contractor and submitted to Landlord's Building Engineer,
ESD Inc., within 30 days of substantial completion. A 12% final payment
retention will be held from General Contractor and all MEP subcontractors until
all as-built drawings are received and APPROVED by ESD at close of project.
There will be no exceptions.

GENERAL INFORMATION

Building security and engineering departments are on duty in the building
twenty-four hours a day, every day of the year.

FINAL CLEAN

Prior to the space being turned over to the tenant/building, the site must be
final cleaned, to standards appropriate for tenant occupancy. The final cleaned
condition must be approved by the Housekeeping Manager. If the condition is
unacceptable for occupancy, building management will have the situation
corrected and backcharge the General Contractor.

Note:  Building management is responsible for post-move in cleaning only.

SCHEDULED WORK

All work that does not take place during regular building business hours (refer
to page 1) should be noted on the After Hours Authorization form and sent to the
building Project Manager as soon as reasonably possible. It is important for
security and life-safety reasons that the security and engineering departments
be aware of contractor presence. If an after hours emergency arises, the
Security Command Center phone (875-7711) must be notified.

AFTER HOURS ACCESS

Entrance to the building after hours is controlled by the security department.
In order to facilitate after hours entrance or departure, it is important that
the building Project


                                     12
<PAGE>

Manager be notified of the need as soon as reasonably possible. This is of
particular importance regarding freight elevator service and the loading dock as
manpower may have to be scheduled to handle the need. If an after hours
emergency arises, you must notify the Security Command Center (875-7711).

PROPERTY PASSES

For anything leaving the building, including tools and parts, a property pass is
required. This pass must be signed by the General Contractor, Job Superintendent
or Foreman. Security officers will not accept them unless they are signed by
authorized personnel. These property passes can be requested from the building
Project Manager.

ACCIDENTS

All accidents must be reported to the Security Command Center immediately. The
security department will dispatch personnel and facilitate the emergency
procedures. In serious cases call 911 for the Chicago Fire Department Paramedics
first, then notify the Security Command Center (875-7711).

FIRES

All fires must be reported to the Security Command Center IMMEDIATELY
(875-7711).

LOCKSMITHING

The building has a full-time locksmith who may consult, order, and install all
locking mechanisms. The locksmith is responsible for all keys and all other
types of locks and the installation of all lock cylinders/cores. Contact the
Director of Mechanical Operations for assistance.

Contractor will be backcharged for lock mechanisms tampered with in construction
area.


                                      13
<PAGE>

                                   SEARS TOWER
                                SAFETY PRACTICES

All contractors and its employees must follow safety practices outlined by
employer, General Contractor and OSHA but not limited to: CONTRACTORS ARE
RESPONSIBLE FOR MAINTAINING AND ENFORCING THEIR OWN SAFETY RULES AND PROCEDURES.
Under no circumstances will Building Management or its employees accept
responsibility for monitoring general safety guidelines. The following
guidelines for safety in the building should be followed BUT IS NOT ALL
INCLUSIVE OF SAFETY PRACTICES REQUIRED BY LAW, OR ANY OTHER RULES THAT MAY
APPLY.

-        Take special precautions if welding or cutting in a confined space is
         stopped for some time. Disconnect the power on ARC welding or cutting
         units and remove the electrode from the holder. Turn off the torch
         valves on gas welding or cutting units, shut off the gas supply at a
         point outside the confined area, and, if possible, remove the torch and
         hose from area.

-        After welding or cutting is completed, mark hot metal or post a warning
         sign to keep workers away from heated surfaces.

-        Follow safe housekeeping principles.

         1.       Don't throw electrode or rod stubs on the floor - discard them
                  in proper waste container.

         2.       Keep construction area as free of debris as possible.

         3.       Keep chemicals secured in approved storage cabinets.

         4.       Keep floors dry and clean.

-       Hard hats must be worn at all times inside the construction area.

-        All contractors must supply a list of all hazardous materials and their
         locations as well as all MSD sheets to the building Project Manager.

-        Keep a fully stocked and clearly marked first aid supply kit on the job
         site at all times.

-        Make sure there are fully charged, appropriate fire extinguishers
         present on the job site.

-        An emergency brigade should be established and drills held. If you
         should need help in establishing a brigade or holding a drill, contact
         the building's Fire & Life Safety Officer.


                                     14
<PAGE>

                                   SEARS TOWER
                         GUIDELINES FOR CUTTING/WELDING

The following guidelines for cutting/welding in the building should be followed,
BUT IT IS NOT ALL INCLUSIVE OF SAFETY PRACTICES REQUIRED BY LAW, OR ANY OTHER
RULES THAT MAY APPLY.

- Make sure that sprinklers are in service.

- Make sure that cutting and welding equipment is in good repair.

PRECAUTIONS WITHIN 35 FEET

- Make sure floors are swept clean of combustibles.

- Combustible floors:  wet down, cover with damp sand or fire-resistive sheets.

- Flammable liquids are removed; other combustibles, if not removed, protected
  with fire-resistive tarpaulins or metal shields.

- Explosive atmosphere in area eliminated.

- All wall and floor openings are covered.

- Fire-resistive tarpaulins are suspended beneath work.

WORK ON WALLS OR CEILINGS

- Construction of the building structure is noncombustible and without
  combustible covering or insulation.

- Make sure combustibles are moved away from the other side of wall.

- Make sure all flammable liquids are purged from the work area.

- Any type of "Hot Work" requires a fire watch, appropriate extinguishers or
  fire hose, and a "Hot Work" Permit.

STRUCTURAL SLABS

- Saw cutting or trenching of floor slab is NOT permitted without prior written
  approval from Landlord and reviewed by building's structural consultant.

WORK ON ENCLOSED EQUIPMENT

- Enclosed equipment cleaned of all combustibles.

- Containers are purged of flammable liquids.


                                     15
<PAGE>

FIRE WATCH

* Fire watch will be provided by the Contractor during and for at least 60
   minutes after work, and during coffee or lunch breaks.(1)

* The fire watch is supplied with suitable extinguishers.

* The fire watch is trained in use of this equipment and in sounding alarm.

* Report the beginning and conclusion of the fire watch to the Security Command
  Center (875-7711).

*****PLEASE FILL OUT ALL APPLICABLE FORMS ATTACHED AND FAX COMPLETED FORMS TO
         ALEX PAPPAS, FAX NUMBER 312-906-1118 IMMEDIATELY UPON SIGNING OF THIS
         CONTRACT.


--------------------------
(1) According to City Code, NFPA, and Factory Mutual Insurance Standards.


                                      16
<PAGE>

                                   SEARS TOWER
                       CONTRACTOR I.D. AUTHORIZATION FORMS

Please fill out the information below as it is required before any I.D.s will be
made. These I.D.s will only allow access in the building Monday through Friday,
6am-6pm. Any work done outside of these hours must be authorized by the Project
Coordinator or General Contractor Superintendent.

Picture I.D.s will be issued to Construction Supervisors. All other contractors
will have non-photo I.D. contractor pass. I.D.s can be taken Monday-Friday from
10am-11am at the Tower Health Club, located on LL3 of the Sears Tower. Please
complete this form and return to the building Project Manager.

COMPANY CONTRACTED BY:__________________________________________________________
                                  (TENANT NAME)

OFFICE CONTACT/SUPERINTENDENT:__________________________________________________

PHONE NUMBER:___________________________________________________________________

FLOORS THAT WORK WILL BE DONE ON:_______________________________________________

ESTIMATED JOB COMPLETION DATE: _________________________________________________

CONSTRUCTION COMPANY NAME:______________________________________________________

SUPERVISOR:    1.____________________________PHONE:_____________________________
                 ____________________________PAGER:_____________________________
                 __________________________CELL PHONE:__________________________

(BACKUP)       2.____________________________PHONE:_____________________________
                 ____________________________PAGER:_____________________________
                 __________________________CELL PHONE:__________________________

NUMBER OF CONTRACTOR I.D.S NEEDED:______________________________________________
                                               (Number of IDs needed)

NUMBER OF DOCK I.D.S NEEDED*:___________________________________________________
________________________________________________________________________________
                                               (Number of IDs needed)

This form must be sent to the Director of Security before any I.D.s will be
issued. All I.D.s will be forwarded to the Project Coordinator or the building
Project Manager and not to the Contractor. All Contractor I.D.s must be returned
to the Office of the Building upon completion of the project. There will be a
$50.00 charge for any I.D.s not returned.

----------------------------------
* Dock IDs will only be issued to contractors who will be responsible for
deliveries/pickups and removing debris from the work area.


                                     17
<PAGE>

If a contractor must access the building during non-business hours, please use
the "After Hours Building Access Authorization Form".


                                     18
<PAGE>

                                   SEARS TOWER
                     CONTRACTOR AFTER HOURS BUILDING ACCESS
                               AUTHORIZATION FORM

Please make sure that all information is filled out correctly and send to the
attention of the building Project Manager.

COMPANY NAME: __________________________________________________________________

PROJECT COORDINATOR: ___________________________________________________________
(OR JOB SUPERINTENDENT)                    (PLEASE SIGN)

CONTRACTOR NEEDING ACCESS: _____________________________________________________

FLOOR:__________________________________ LOCATION:______________________________

DATE OF ACCESS: ________________________________________________________________

TIME PERIOD OF ACCESS:__________________________ UNTIL: ________________________

BRIEF DESCRIPTION OF WORK: _____________________________________________________

If access to occupied tenant space is necessary, please present evidence of
TENANT AUTHORIZATION with this form or forward a request for such access NO LESS
THAN 48 HOURS IN ADVANCE TO WHEN THE WORK WILL COMMENCE.

Anyone accessing the building will be required to show the security officer a
type of photo identification card and Company ID. Please indicate the Supervisor
who will be in charge and if at all possible the name of the construction
workers who will be working in your space. If specific names are not known then
please list the number of workmen per trade:

______________________________________________________________________
(Supervisor)
______________________________________________________________________

______________________________________________________________________

______________________________________________________________________

______________________________________________________________________
NOTE:  There is a service charge for any lock or unlock requests made of the
security department.

 ALL ACCESS NOTICES MUST BE RECEIVED BY BUILDING SECURITY 24 HOURS IN ADVANCE.


                                     19
<PAGE>

                                   SEARS TOWER
                            PROJECT INFORMATION SHEET

Please fill out the information listed below. This information must be completed
before any work can begin in your space. Once this information has been
completed please send to the building Project Manager, in the Office of the
Building.

PROJECT:________________________________________________________________________

LOCATION:_______________________________________________________________________

GENERAL CONTRACTOR:_____________________________________________________________

SUPERINTENDENT:_________________________________________________________________

DAYTIME PHONE NUMBER:___________________________________________________________

AFTER HOURS PHONE NUMBER:_______________________________________________________

PAGER NUMBER:___________________________________________________________________

NORMAL WORKING HOURS:___________________________________________________________

DURATION OF PROJECT:____________________________________________________________

SUBCONTRACTORS:  (INCLUDE M.E.P, CONTRACTORS AFTER HOUR PHONE NUMBER AND PAGER
NUMBER)

______________________________________________________________________

______________________________________________________________________

______________________________________________________________________

=======================================

This section to be completed by the Office of the Building

BUILDING                                                                 PROJECT
MANAGER:_____________________________EXT.__________


                                     20
<PAGE>

                                   SEARS TOWER
                        CONSTRUCTION BADGES REQUEST FORM


This receipt confirms that the number of badges listed below were received by
the signee. All badges are to be returned to the building Project Manager upon
completion of the project. There will be a $50.00 charge for any I.D.s not
returned.


ISSUED TO:______________________________________________________________________
                                            (YOUR NAME)

COMPANY NAME: __________________________________________________________________

NUMBER OF BADGES REQUESTED:_____________________________________________________



PROJECT:________________________________________________________________________

FLOOR: _________________________________________________________________________



RECEIVED BY:                                               DATE:

___________________________________             ________________________________
(PLEASE PRINT YOUR NAME)

___________________________________
(PLEASE SIGN YOUR NAME)


                                      21
<PAGE>

                                   SEARS TOWER
                              CONSTRUCTION DISPOSAL
                                COUPON ORDER FORM
                     (TO BE COMPLETED BY GENERAL CONTRACTOR)

NAME OF PROJECT_________________________________________________________________

PROJECT START DATE______________________________________________________________

NAME OF APPLICANT_______________________________________________________________

PROJECT COMPLETION DATE_________________________________________________________

CONTRACT WITH___________________________________________________________________

ESTIMATED YARDS OF WASTE FOR ENTIRE PROJECT_____________________________________

TOTAL NUMBER OF COUPONS REQUESTED TODAY_________________________________________

TO DATE  ___________________________________

--------------------------------------------------------------------------------
                 (TO BE COMPLETED BY TRIZECHAHN PERSONNEL ONLY)


TRIZECHAHN AUTHORIZATION________________________________________________________

COUPON NUMBERS          #________________THROUGH #_____________________________

AMOUNT OF PAYMENT RECEIVED $________CHECK #:__________________________


                                      22

November 1, 1999

<PAGE>

                                   SEARS TOWER
                   CONTRACTOR'S FREIGHT/DOCK DELIVERY REQUEST

TODAY'S DATE: __________________________________________________________________

CONTRACTOR: ____________________________________________________________________

TENANT NAME: ___________________________________________________________________

FLOOR #: _______________________________________________________________________

CONTACT: ___________________________________ TELEPHONE #:_______________________

THIS WILL SERVE AS A WRITTEN REQUEST FOR PRIORITY FREIGHT ELEVATOR/DOCK SERVICE
FOR THE ABOVE-MENTIONED CONTRACTOR/TENANT.

DELIVERY DATE: _____________________________

DELIVERY TIME: _____________________________TO__________________________________
                       (START TIME)                  (STOP TIME)

TIMES WILL BE STRICTLY ENFORCED.
AVAILABLE TIMES ARE BETWEEN 4:00 AM AND 6:00 AM

PURPOSE: _______________________________________________________________________
                  (TYPE OF DELIVERY)

A SERVICE FEE OF $30.00 PER HOUR WILL BE CHARGED TO THE CONTRACTOR/TENANT.

COMMENTS: ______________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________


FOR OFFICE USE ONLY:

APPROVED AND FORWARDED BY: _____________________________________________________

DISTRIBUTION:     LEROY BROWN
                  SECURITY - LL3
                  CARLOS VILLARREAL


                                      23

November 1, 1999

<PAGE>

                                    EXHIBIT C
                              RULES AND REGULATIONS

1.       Tenant shall not in any manner deface or injure the Building or any
         part thereof, nor do anything tending to injure the reputation of the
         Building or its occupants.

2.       Except as provided in Section 26(v) of the Lease, Tenant shall not
         install any sign, lettering, picture, notice, advertisement or object
         unacceptable to Landlord against glass partitions, doors or windows
         which would be visible from the Building's corridors, or place same on
         any outside window or in a position visible from outside the Building.
         Tenant agrees to promptly remove same upon notice from Landlord. Any
         sign, lettering, picture, notice or advertisement installed within the
         Premises which is visible to the public from within the Building shall
         be installed at Tenant's cost and in such manner, character and style
         as approved by prior written consent of Landlord.

3.       Tenant shall not, in advertising or other publicity, without prior
         written consent of Landlord, use the name of the Building (Sears Tower)
         or use pictures or illustrations of the Building.

4.       The Tenant's mailing address shall include:

                  (Name of Company)
                  233 South Wacker Drive
                  Chicago, Illinois  60606-________

5.       Tenant shall not obstruct sidewalks, entrances, passages, courts,
         corridors, vestibules, halls, elevators, loading docks, escalators and
         stairways in and about the Building.

6.       Tenant shall not make noises, cause disturbances or vibrations or use
         or operate any electrical or electronic devices or other devices that
         emit sound or other waves or disturbances, or that create a fire
         hazard, or create odors, any of which may be offensive to other Tenants
         and occupants of the Building or that would interfere with the
         operation of any device or equipment or radio or television
         broadcasting or reception from or within the Building or elsewhere, and
         shall not place or install any projections, antennae, aerials or
         similar devices inside or outside the Premises.

7.       Tenant shall not make any canvass in the Building to solicit business
         or for any other reason.

8.       Tenant shall not exhibit, sell or offer to sell, use, rent or exchange
         any item or service in or from the Premises unless ordinarily embraced
         within the Tenant's use of the Premises specified herein.

9.       Tenant shall report all peddlers, solicitors and beggars immediately to
         the office of the Building or as Landlord otherwise requests.

10.      Tenant shall not waste water and agrees to cooperate fully with
         Landlord to assure the most effective operating of the building's
         heating and air conditioning, and shall refrain from adjusting any
         controls other than room thermostats installed for Tenant's use, and


                                      C-1
<PAGE>

         shall keep public corridor doors closed, and shall not block any
         heating and air conditioning induction units.

11.      Tenant shall not employ persons to do janitor work in the Premises and
         no persons other than the janitors of the Building shall clean the
         Premises without prior written consent of Landlord. With prior written
         consent of Landlord, any person employed by Tenant to do janitor's work
         shall, while in the Building, either inside or outside of the Premises,
         be subject to and under the control and direction of the manager of the
         Building (but not as agent or servant of said manager or Landlord).

12.      Tenant shall not:

         (a)      Cook in the Premises;

         (b)      Place vending or dispensing machines of any kind in or about
                  the Premises;

         (c)      At any time sell, purchase or give away, or permit the sale,
                  purchase or gift of, food in any form;

         however, with prior written consent of Landlord, such activities may be
         permitted in lounges or other facilities specifically designated for
         this purpose.

13.      Tenant shall not:

         (a)      Use the Premises for lodging or for any immoral or illegal
                  purposes.

         (b)      Use the Premises to engage in the manufacture or sale of, or
                  permit the use of, any spirituous, fermented, intoxicating or
                  alcoholic beverages on the Premises.

         (c)      Use the Premises to engage in the manufacture or sale of, or
                  permit the use of, any illegal drugs on the Premises.

14.      Tenant shall not install any equipment utilizing an ammonia process or
         using any ammonia products or any other noxious process necessitating
         venting.

15.      Tenant shall not bring firearms into the Premises.

16.      Tenant shall keep doors and other means of entry to the Premises closed
         and secured.


                                     C-2
<PAGE>

                                    EXHIBIT D

                       FORM OF TENANT ESTOPPEL CERTIFICATE

                              ESTOPPEL CERTIFICATE

Landlord:                  TH Tower Leasing LLC

Tenant:

Address of Tenant:         Suite _____ consisting of approximately _____ square
                           feet of Rentable Area on the _____ Floor(s) of the
                           Building

Lease:                     That certain Lease, dated ______________________,
                           199__, by and between Landlord and Tenant, including
                           the Work Letter and the Condenser Water Addendum, if
                           any,and the following amendments, if any, (the
                           "Lease", a copy of which is attached and made a part
                           hereof).

Commencement Date:

Expiration Date:

Security Deposit                    $_______________

Monthly Base Rent:                  $_______________

Monthly License Fee:                $_______________

Monthly Base Rent and

License Fee Paid Through:

Percentage Rent:  ___% of Sales in excess of $___ Monthly

Current Estimated Monthly
Installment of the Expense
Adjustment Amount:                  $_______________

Current Estimated Monthly
Installment of the Tax
Adjustment Amount:                  $_______________

Lenders: Metropolitan Life Insurance Company and Partners Tower, L.P. (and/or
additional lenders, their respective successors and assigns).

1.       In order to induce Lenders to make loans secured by, among other
         things, Mortgages on property (the "property") which includes the
         Premises, Tenant hereby certifies as true and correct the following
         statements:


                                      D-1
<PAGE>

         (a)      The Lease is a true, correct and complete agreement between
                  Landlord and Tenant with respect to the premises described
                  therein (the "Premises").

         (b)      The Lease is in full force and effect and constitutes the
                  entire agreement between Landlord and Tenant. The Lease has
                  not been amended, modified, supplemented or changed, whether
                  in writing or orally (including, without limitation, any
                  agreement by Landlord to assume any lease of Tenant covering
                  space in other property), except as disclosed herein.

         (c)      Tenant is in sole possession of and is occupying the Premises.
                  Except as specified below, Tenant is not in any respect in
                  default under the Lease and has not subleased all or any part
                  of the Premises or assigned the Lease, or otherwise
                  transferred or hypothecated its interest in the Lease or the
                  Premises.

         (d)      The Commencement Date and Expiration Date of the term of the
                  Lease are correctly stated above. Tenant has no options or
                  rights of renewal, extension, expansion, purchase or first
                  refusal concerning the Lease, the Premises or other space
                  within the building of which the Premises are a part, except
                  as may be stated in the Lease. Tenant has not exercised any
                  option or rights to renew, extend, amend, modify, or change
                  the term of the Lease, except as may be stated in the Lease.
                  Tenant does not have any preferential right to purchase all or
                  any part of the property of which the Premises are a part.

         (e)      The Monthly Base Rent (License Fee and Percentage Rent) and
                  other amounts payable under the Lease are correctly stated
                  above. Monthly Base Rent (and License Fees) has (have) been
                  paid through the date stated above. Tenant has not prepaid any
                  rent for more than one (1) month and is paying rent under the
                  Lease on a current basis with no offsets, credits, claims or
                  setoffs. Tenant has not been given any free rent, partial
                  rent, rebates, rent abatements, or rent concessions of any
                  kind, which are unexpired, except as disclosed herein.

         (f)      Tenant has deposited the Security Deposit stated above with
                  Landlord, and to the best of Tenant's knowledge, none of the
                  Security Deposit has been applied by Landlord to the payment
                  of rent or any other amounts due under the Lease.

         (g)      As of the date hereof, Landlord has fully performed all of its
                  obligations under the Lease and has satisfied all commitments
                  made to induce Tenant to enter into the Lease. To the best of
                  Tenant's knowledge, Landlord is not in default under the terms
                  and conditions of the Lease and no event has occurred which
                  would constitute a default under the Lease, either upon
                  service of notice or passage of time. To the best of Tenant's
                  knowledge, no claim, controversy or dispute exists between
                  Tenant and Landlord. As of the date hereof, Tenant is not
                  asserting that the Lease is not fully enforceable by Landlord
                  in accordance with its terms.

         (h)      All construction, build-out, improvements, or alterations to
                  the Premises required under the Lease have been fully
                  completed in accordance with the plans and specifications
                  described in the Lease and all contributions required to be
                  made by Landlord on account thereof have been made.


                                      D-2
<PAGE>

         (i)      Landlord has not previously given any consent to Tenant (i.e.,
                  consent to sublease or alter the Premises) that is required
                  under the Lease before the taking of any action by Tenant,
                  except as disclosed herein.

         (j)      Tenant is not insolvent and is able to pay its debts as they
                  mature. There are no actions, whether voluntary or otherwise,
                  pending against Tenant under the bankruptcy or insolvency laws
                  of the United States or any state thereof.

2.       Tenant agrees that from and after the date hereof, Tenant will not pay
         any rent under the Lease more than thirty (30) days in advance of its
         due date.

3.       Tenant hereby certifies that the address for notices to Tenant under
         the Lease is correctly set forth above.

         This certificate has been given to Lenders with the understanding that
Lenders will rely hereon in connection with loans which will be secured by the
property of which the Premises constitute a part. The undersigned hereby
certifies that he or she is duly authorized to sign and deliver this Estoppel
Certificate.

         IN WITNESS WHEREOF, Tenant has caused this Estoppel Certificate to be
executed by its duly authorized representative as of the ____ day of
___________, _____.

                                        TENANT:


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

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

                                     D-3
<PAGE>

                                    EXHIBIT E

                            CONDENSER WATER ADDENDUM

This Condenser Water Addendum constitutes a part of the Lease, dated March 10,
2000, between TH TOWER LEASING LLC, a Delaware limited liability company, as
Landlord, and UNIVERSAL ACCESSS, INC., a Delaware corporation, as Tenant, for
premises as described in the Lease located at 233 South Wacker Drive, Chicago,
Illinois (the "Premises").

         WHEREAS, Landlord has constructed and is operating an auxiliary
condenser water system (the "System") for its use and the use of tenants in the
Building; and

         WHEREAS, Tenant is desirous of connecting certain facilities to the
System to be indicated on the plans;

         NOW, THEREFORE, the parties agree as follows:

Tenant shall advise Landlord of its requirements for condenser water use,
determined separately for each floor of the Premises, and furnish to Landlord
plans and specifications of its facilities which it proposes to connect to the
System.

Upon Landlord's approval thereof and payment of Landlord's costs in connection
therewith, Landlord shall grant to Tenant the right to connect its facilities to
the System which connection shall be made only by Landlord's approved
contractor.

Prior to making said connection, Tenant shall pay Landlord a one time
"Connection Fee" of $500.00.

Tenant shall pay to Landlord a "Monthly Fee" for its dedicated capacity on the
System. The fee shall be calculated as follows:

                  CONDENSER WATER RATE -

                  (GPM x 60) x 728 hours per month x cost per gallon = Monthly
                  Fee

                  (GPM is to be calculated by using the equipment manufacturer's
                  technical specifications based on a condenser entering water
                  temperature (EWT) of 85 degrees Fahrenheit and a condenser
                  water temperature rise (WTR) of 10 degrees Fahrenheit).

All proposed changes in Tenant's facilities shall be submitted to Landlord in
advance for Landlord's approval. No changes shall be made in Tenant's facilities
without prior written approval of Landlord. Landlord shall have the right to
designate such conditions and charges for the making of Tenant's changes as
Landlord deems appropriate. It is expressly agreed that Landlord may refuse to
make any changes which increase the amount of condenser water supplied to
Tenant.


                                      E-1
<PAGE>

All the terms and conditions of the Lease shall apply to this Addendum.

This Addendum shall become effective on the Commencement Date and will terminate
on the termination of the Lease.

         IN WITNESS WHEREOF, Landlord and Tenant have caused this Condenser
Water Addendum to be duly executed this 10th day of March, 2000.



                                        LANDLORD:

                                        TH TOWER LEASING LLC,
                                        a Delaware limited liability company


                                        By: /s/ Stephen E. Budorick
                                           ------------------------------------

                                        TENANT:

                                        UNIVERSAL ACCESS, INC.,
                                        a Delaware corporation


                                        By: /s/ Robert Brown
                                           ------------------------------------


                                     E-2
<PAGE>

                                    EXHIBIT F

                               GENERATOR LOCATION


                                     F-1
<PAGE>

                                  EXHIBIT G

                                   SIGNAGE









                                     G-1
<PAGE>

tenant work letter switched for version 2 VPM 12-07-99









                                     G-2