4450 Fashion Boulevard (Saginaw Township, MI) Lease Agreement - Saginaw Video Associates and Concentric Network Corp.


                                LEASE AGREEMENT
                                ---------------


     THIS AGREEMENT made the 1st day of November, 1996, effective the 11th day
of March, 1996, by and between SAGINAW VIDEO ASSOCIATES, a Michigan General Co-
Partnership, d/b/a Saginaw Conference Center, of 5195 Hampton Place, Saginaw,
Michigan 48604-9576 ('Landlord'), and CONCENTRIC NETWORK CORPORATION, a Florida
Corporation, authorized to do business in the State of Michigan, with offices at
400 Forty-First Street, Bay City, Michigan 48708 ('Tenant').  Landlord and
Tenant are also collectively referred to as the 'parties.'

     1.   Premises.  Subject to the terms and conditions herein contained,
          --------                                                        
Landlord leases to Tenant, and Tenant leases from Landlord, the following space,
including rights of ingress, egress and parking:

          (a) Existing Space.  An existing 11,600 square foot conference center
              --------------                                                   
located at 4450 Fashion Square Boulevard, Saginaw Township, Saginaw County,
Michigan, more particularly described as follows, to-wit:

          'A parcel of land being a part of the so-called North 55
          acres of the Southwest 1/4 of Section 2, Town 12 North,
          Range 4 East, Saginaw Township, Saginaw County, Michigan,
          described as follows: To fix the Point of Beginning
          commence at the South 1/4 corner of said Section 2; thence
          North 00(degrees)-03'-45' East on the North and South 1/4
          line of said Section, 2,621.31 feet to the center post of
          said Section; thence North 89(degrees)-45'-53' West on the
          East and West 1/4 line of said Section, 650.00 feet; thence
          South 00(degrees)-03'-45' West, parallel with said North
          and South 1/4 line, 43.00 feet to a point on the South line
          of Schust Road right-of-way and the Point of Beginning of
          this description; thence continuing South 00(degrees)-03'-
          45' West, parallel with said North and South 1/4 line,
          412.08 feet; thence North 89(degrees)-49'-39' West, on a
          line which is parallel with and 454.44 feet, measured at
          right angles, North of the South line of said so-called
          North 55 acres, said South line being evidenced by the
          remains of a fence line which if extended would intersect
          the West line of said Section at a point 911.68 feet, South
          00(degrees)-00'-00' West, on the West 1/4 corner of said
          Section and also would intersect the North and South 1/4
          line at a point 908.81 feet, South 00(degrees)-03'-45' West
          of the center of said Section, 334.66 feet; thence North
          03(degrees)-06'-33' West on the Easterly right-of-way line
          of Schust Road, 357.52 feet to the Point of Beginning'

 
          (b) Additional Space.  New space consisting of approximately 10,000
              ----------------                                               
square feet, being an addition to the Existing Space located at 4450 Fashion
Boulevard, Saginaw Township, Saginaw County, Michigan.

     Existing Space and Additional Space are also collectively referred to as
the 'Premises.'

     Attached as Exhibit 'A,' and incorporated as part of this Lease is a site
plan which indicates driveways and parking areas.

     2.   Initial Lease Term.
          ------------------ 

          (a) Existing Space.  The Initial Lease Term for the Existing Space
              --------------                                                
shall be for a period of approximately sixty-nine (69) months, commencing the
15th day of March, 1996, or on the date possession is given to Tenant, if later,
and terminating the 31st day of December, 2001, unless otherwise terminated or
extended as provided herein.

          The parties acknowledge occupancy with respect to the existing space
as of March 11, 1996.

          (b) Additional Space.  The Initial Lease Term for the Additional
              ----------------                                            
Space, shall be for a period of approximately sixty-three (63) months,
commencing the 1st day of October, 1996, or on the date possession is given to
Tenant, if later, and terminating on the 31st day of December, 2001, unless
otherwise terminated or extended as provided herein.

          Notwithstanding the foregoing, the Lease, with respect to the
additional space, shall not commence until all of the following have occurred:

          (i)       Landlord has substantially completed the Tenant improvements
('Tenant Improvements'), Landlord is required to construct pursuant to the
'Binding Lease Commitment' between the parties dated February 8, 1996.
                    
          (ii)      There remains no incomplete or defective item of Tenant
Improvements which would materially, adversely affect Tenant's intended use of
the Premises.

          (iii)     Landlord has delivered possession of the Premises to
Tenant.

          (iv)      Landlord has obtained all approvals and permits from the
appropriate governmental authorities required for the legal occupancy of the
Premises for Tenant's intended use. Landlord shall be obligated to construct the
Tenant Improvements using new materials and equipment of good quality, in a good
and workmanlike manner and in accordance with applicable laws.  Tenant may be
granted early entry rights to construct its improvement work, subject to all of
the terms and conditions of the Lease, except for the payment of rent.

                                      -2-

 
          (c) Acknowledgment.  The parties shall execute an Acknowledgment
              --------------                                              
acknowledging commencement of the Initial Lease Term.  If, as a result beyond
its reasonable control, Landlord is unable to deliver possession of the Premises
by the date specified for commencement of the Initial Lease Term, Landlord shall
not be liable for any damage caused for failure to deliver possession and the
Lease shall not be void or voidable.

     3.   Extended Lease Term.  Provided Tenant is not in default under this
          -------------------                                               
Lease, Tenant shall have the right to extend the Initial Lease Term for the
Premises for one (1) additional term of sixty (60) months commencing the 1st day
of January, 2002, and terminating the 31st day of December, 2006, unless
otherwise terminated as provided herein ('Extended Lease Term').  In the event
Tenant desires to extend the Initial Lease Term, Tenant shall give notice to
Landlord, in writing, at least one hundred eighty (180) days prior to expiration
of the Initial Lease Term in conformity with the notice provisions of this
Lease.

     4.   Rent.
          ---- 

          (a) Initial Lease Term.  During the Initial Lease Term, Tenant shall
              ------------------                                              
pay to Landlord, as rent for the Premises, the sum of TEN ($10.00) DOLLARS, per
square foot.

          Until commencement of the Initial Lease Term, as it relates to the
Additional Space, Tenant shall pay to Landlord, rent for the Existing Space in
the amount of NINE THOUSAND SIX HUNDRED SIXTY-SEVEN ($9,667.00) DOLLARS per
month.

          Upon commencement of the Initial Lease Term, as it relates to the
Additional Space, the exact square footage of the Premises (Existing and
Additional Space), shall be calculated and Tenant shall be obligated to pay rent
to Landlord, on an exact square foot basis, at the rate of TEN ($10.00) DOLLARS,
per square foot.

          At that time, the parties agree to execute and attach to this Lease, a
Certificate of Agreed Square Footage certifying the total square footage of the
Premises and total rent payable based on that square footage for the balance of
the Initial Lease Term and the first (1st) year of the Extended Lease Term.

          (b) Extended Lease Term.  During the Extended Lease Term, Tenant shall
              -------------------                                               
pay to Landlord, as rent for the Premises, the sum of TWELVE ($12.00) DOLLARS,
per square foot. Exact rent, based upon square footage, shall be calculated
pursuant to Subsection 4(a), entitled 'Rent/Initial Lease Term.'

          Rent during the remainder of the Extended Lease Term shall be adjusted
as follows: commencing as of the first (1st) day of the thirteenth (13th)
calendar month following the commencement date of the Extended Lease Term, and
continuing on each annual anniversary of such day throughout the remainder of
the Extended Lease Term (each such day being referred to as a 'Rent Adjustment
Date'), the monthly rent shall be adjusted to equal the product of the monthly
rent in effect for the calendar month immediately preceding the Rent Adjustment
Date multiplied by a 

                                      -3-

 
fraction, the numerator of which shall be the Consumer Price Index published for
the month immediately preceding the Rent Adjustment Date in question and the
denominator of which is the Consumer Price Index published for the month
immediately preceding the commencement of the Extended Lease Term (with respect
to the first rent adjustment), or the immediately preceding Rent Adjustment Date
(with respect to each other rent adjustment); provided however, that unless the
Consumer Price Index increases by ten (10%) percent over that published for the
month of March, 1996, in no event shall the monthly rent on a Rent Adjustment
Date be more than four (4%) percent greater than the monthly rent due for the
immediately preceding period. The term 'Consumer Price Index' shall mean the
Consumer Price Index for the Detroit Metropolitan Area, which is currently
published by the United States Department of Labor, Bureau of Labor Statistics.
if however, this Consumer Price Index is changed so that the base year is
altered from that used as of the commencement of the Extended Lease Term, then
the Consumer Price Index shall be converted in accordance with the conversion
factor published by the United States Department of Labor, Bureau of Labor
Statistics, to obtain the same results that would have been obtained had the
base year not been changed. If no conversion factor is available, or if the
Consumer Price Index is otherwise changed, revised or discounted for any reason,
there shall be substituted in lieu thereof and the term 'Consumer Price Index'
shall thereafter refer to the most nearly comparable official price index of the
United States Government to obtain substantially the same result as would have
been obtained had the original Consumer Price Index not been changed, revised or
discontinued, which alternative index shall be selected by Landlord and shall be
subject to Tenant's reasonable, prior, written approval.

          (i) Except as otherwise expressly set forth herein, all rent shall be
due and payable in full and without right of set-off or other deduction in
advance on the first (1st) day of each and every month during the Initial Lease
Term and any extension thereof; provided however, that Tenant shall not be
liable for rent until Landlord delivers possession to Tenant.  Rent shall be
pro-rated on a per diem basis, payable in advance, for any partial months.

     All rents shall be paid to Landlord by direct deposit into Landlord's
Account No. ________________ maintained at Citizens Bank, N.A., Saginaw,
Michigan, or at such other place as Landlord may reasonably designate from time
to time, in writing.

     5.   Deposit.  Tenant shall not be required to tender a security deposit to
          -------                                                               
Landlord under this Lease.

     6.   Condition of Premises/Representations.  Except as Landlord and Tenant
          -------------------------------------                                
may otherwise agree in writing, Tenant's entry into possession shall constitute
conclusive evidence against Tenant that Tenant has inspected the Existing Space
and found the same to be in good order and satisfactory condition at the time of
entry and that Tenant has accepted the Existing Space in its present 'as is'
condition.  Tenant agrees to keep the Existing Space in a like condition as when
possession was given to Tenant, normal wear and tear expected.  Except as
expressly set forth herein, neither Landlord, nor Landlord's agents have made
any representations or promises with respect to the physical condition of the
Existing Space, or any portion thereof, or any other matter pertaining to the
Premises.

                                      -4-

 
     Electricity, water, janitorial, heating, ventilating, air conditioning and
other services, at levels generally provided for office uses in comparable
buildings in the vicinity of the Premises, shall be available to Tenant at all
times during the Lease Term.

     Tenant shall have the right to submit a written 'punch list' to Landlord,
setting forth any defective item of Tenant Improvements, and Landlord shall
cause such items to be corrected promptly.  Tenant's acceptance of the Premises
or submission of a 'punch list' shall not be deemed a waiver of Tenant's right
to have defects in Tenant Improvements or the Premises repaired by Landlord at
no cost to Tenant.

     Landlord and Tenant shall reaffirm the provisions of this Section as to the
Additional Space at such time as Tenant enters into possession of the Additional
Space; provided however, that to the best of Landlord's knowledge, Tenant's use
of the Premises will be permitted by all fire underwriter's requirements, and
all rules, regulations, statutes, ordinances, laws and building codes
(collectively 'Laws').

     7.   Appurtenant Rights.  Tenant shall have full and unimpaired access to
          ------------------                                                  
the Premises at all times during the Initial Lease Term and any extension
thereof.

     8.   Taxes and Assessments.
          --------------------- 

          (a) Real Property Taxes.  Landlord shall bill Tenant for, and Tenant
              -------------------                                             
shall pay, prior to delinquency, all real property taxes, including general and
special assessments, levied or assessed against the Premises during the Initial
Lease Term and any extension thereof.  Landlord's billing shall include a copy
of all underlying tax bills.  Taxes shall be pro-rated on a per diem basis for
any partial years.  Taxes shall be deemed paid in advance and shall be based
upon the most recent tax bill, utilizing a due date basis.

          (b) Personal Property Taxes.  Tenant shall pay, prior to delinquency,
              -----------------------                                          
all taxes, assessments, license fees and other charges, levied or assessed
against Tenant's personal property installed or located in, on or about the
Premises, or that become payable during the Initial Lease Term and any extension
thereof.

     Tenant shall, at Tenant's sole cost, have the right to seek a reduction of
the assessed valuation of the Premises or to contest any real or personal
property taxes to be paid by Tenant.

     Tenant's obligation to pay taxes shall be conditioned upon Tenant's prompt
receipt of any tax bills received by Landlord with respect to the Premises.
Additionally, Tenant's obligation to pay taxes shall not include any taxes,
assessments or other governmental levies and any increases in the foregoing
occasioned by or relating to:  (i) land and improvements not reserved for
Tenant's exclusive or non-exclusive use; (ii) a voluntary or involuntary change
of ownership or other conveyance of the real property of which the Premises is a
part; or (iii) assessments and other fees for improvements and services which do
not benefit the Premises.

                                      -5-

 
     9.   Maintenance.  Tenant shall, at Tenant's sole expense, maintain the
          -----------                                                       
Premises in good condition.

     Landlord shall not have any responsibility to maintain the Premises, except
for structural elements of the Premises, including foundation, load-bearing
walls, structural roof system, and the roof membrane (in water-tight condition).

     Tenant shall not be responsible for the performance of any repair,
maintenance or improvement:

          (a) Necessitated by the acts or omissions of Landlord or Landlord's
agents.

          (b) Occasioned by the power of eminent domain.

          (c) Required as a consequence of any violation of Laws or construction
defect in the Premises as of the commencement date of the Lease.

          (d) For which Landlord has a right of reimbursement from others.

     Additionally, Tenant shall have no obligation to undertake any repairs
costing in excess of $5,000.00 which could be treated as capital improvement
under generally accepted accounting principles.  Instead, Landlord shall be
required to undertake such repairs, the cost of which shall be amortized over
the useful life of the improvement in question in accordance with generally
accepted accounting principles.  Tenant shall be responsible for payment of the
monthly amount of the improvement as so amortized during the Lease Term.

     10.  Insurance.
          --------- 

          (a) Public Liability/Property Damage Insurance.  Tenant shall, at
              ------------------------------------------                   
Tenant's sole expense, maintain public liability and property damage insurance,
with liability limits not less than $1,000,000.00 per person and $2,000,000.00
per occurrence, and property damage limits of not less than $500,000.00 per
occurrence with an aggregate coverage of $2,000,000.00 insuring against all
liability of Tenant and Tenant's authorized representatives, arising out of or
in connection with Tenant's use or occupancy of the Premises.

          All insurance policies shall name the Landlord as an additional
insured and shall contain cross-liability endorsements.

          (b) Fire Insurance.  Tenant shall, at Tenant's sole expense, maintain
              --------------                                                   
on the building and all other improvements which are part of the Premises, a
policy of standard fire and extended coverage insurance, with vandalism and
malicious mischief endorsements, to the extent of full replacement value.  The
policy shall be issued in the name of Tenant as insured, with Landlord and
Landlord's lender as an additional insured under a standard mortgagee
endorsement.

                                      -6-

 
     Subject to the provisions of Section 15, entitled
'Destruction/Restoration,' Tenant shall indemnify and hold Landlord and any
mortgagees harmless from all claims, demands, actions, losses, damages and
liabilities, and all fees, costs and expenses, including reasonable legal fees,
relating to or in any way arising from Tenant's use of the Premises, from any
cause whatsoever; provided however, that Tenant shall have no obligation to
indemnify Landlord, or any other party, from any claims, demands, losses or
other liability with respect to the Premises to the extent that same arises from
the negligence or wilful misconduct of Landlord or Landlord's employees, agents
or contractors.

     All insurance policies covering the Premises, including fire and liability,
shall provide for a thirty (30) day right of notice to Landlord prior to
cancellation for any reason.

     Tenant shall not do, bring, or keep any item, article, object or thing in,
on or about the Premises which may cause a cancellation of any insurance
covering the Premises.

     Landlord and Tenant hereby release each other from any and all liability or
responsibility (to the other or to anyone claiming through or under them by way
of subrogation or otherwise), or any loss or damage to Premises caused by fire
or any of the extended coverage or supplementary contract casualties, even if
such fire or other casualty shall have been caused by the fault or negligence of
the other party, or anyone for whom such party may be responsible, provided
however, that this release shall be applicable and in force and effect only with
respect to loss or damage occurring during such time as the releasor's policies
contain a clause or endorsement to the effect that any such release shall not
adversely affect or impair said policies or prejudice releasor's right to
recover thereunder. Landlord and Tenant each agree that their policies shall
include such a clause or endorsement so long as the same shall be obtainable
without extra cost, or if extra cost shall be charged, so long as the other
party pays the extra cost.  If extra cost shall be chargeable, each party shall
advise the other of the amount of the extra cost, and the other party, at its
election, may pay the same, but may not be obligated to do so.

     11.  Utilities.  Tenant shall make arrangements for and be responsible for
          ---------                                                            
the payment of all utilities and services furnished to the Premises or used by
Tenant, including, without limitation, gas, electricity, water, telephone
service, trash collection, and all connection charges.  Landlord shall not be
liable to Tenant for damages or otherwise for any failure or interruption of any
such service furnished to the Premises, provided that such failure or
interruption was not due to the negligence or wilful misconduct of Landlord or
its agents, employees, contractors or invitees.

     12.  Use of Premises.  Tenant shall occupy and use the Premises as general
          ---------------                                                      
offices for its computer networking operation, sales, research, development and
marketing, and for no other use without the prior consent of Landlord, which
consent shall not be unreasonably withheld or delayed.

     13.  Compliance.  Tenant shall promptly observe and comply with:
          ----------                                                 

          (a) All present and future environmental laws, ordinances,
requirements, orders, directions, rules and regulations of the federal, state,
county and township governments, and of all 

                                      -7-

 
other governmental authorities, having or claiming jurisdiction, directly or
indirectly, over the Premises.

          (b) All present and future laws concerning the Premises or Tenant's
use of the Premises, including, without limitation, the obligation of Tenant, at
Tenant's sole expense, to alter, maintain or restore the Premises in compliance
and conformity with all laws related to the condition, use or occupancy of the
Premises.

          (c) Landlord warrants that, as of the commencement date of this Lease,
the Premises conforms to all underwriter's requirements and Laws applicable
thereto.

     14.  Alterations.  Tenant shall not make any alterations to the Premises
          -----------                                                        
without the prior, written consent of Landlord, which consent shall not be
unreasonably withheld.

     All alterations shall be made in a workmanlike manner so as not to weaken
the building on the Premises or lessen the value of the Premises.  Tenant shall
pay all bills arising out of labor and materials for work performed, and shall
cause to be removed of record, within thirty (30) days after filing, all notices
and affidavits for construction liens filed with respect to the Premises, or any
part thereof.  Tenant, at Tenant's option, may bond around any construction
liens.  Tenant shall indemnify, defend and hold Landlord harmless against all
liability, loss, damage, costs and all other expenses arising out of claims of
lien for work performed or materials furnished to or for the benefit of Tenant.

     Landlord may impose conditions with respect to such alterations or
renovations concerning the disposal or removal of same upon termination of this
Lease.

     All alterations made shall remain on, and be surrendered with the Premises
upon expiration of the Initial Lease Term or any extension thereof, or upon
termination of the Lease, unless Landlord requires removal, with restoration of
the Premises to the condition existing prior to the alterations.

     15.  Destruction/Restoration.  If during the Initial Lease Term or any
          -----------------------                                          
extension thereof, the Premises is damaged or destroyed, in whole or in part,
rendering the Premises totally or partially inaccessible or unusable, Tenant
shall restore the Premises, or the part thereof so damaged, as nearly as
possible to the value, condition and character of the Premises immediately prior
to the occurrence of such damage or destruction.  Tenant shall not be entitled
to any reduction or an abatement of rent in the event of destruction to the
extent that such destruction interferes with Tenant's use of the Premises.

     Notwithstanding the foregoing, Tenant's obligations under this Section 15
shall in no event require the Tenant to expend more than $1.25 million.

     16.  Eminent Domain.  If all or any material part of the Premises shall be
          --------------                                                       
taken or condemned by any competent authority for any public use or purpose, the
current Lease Term shall, at the option of Landlord, and as of the date of the
actual taking.  If the Premises may not reasonably 

                                      -8-

 
be used for the purpose contemplated by this Lease following any taking, Tenant
may terminate this Lease. In either case, there shall be no apportionment to
Tenant of any portion of the award or damages for such taking; provided however,
that Tenant shall be entitled to any funds awarded it for moving expenses or
business interruption, loss of goodwill and the unamortized value allocable to
the remainder of the Lease Term of any trade fixtures, alterations or other
improvements installed in the Premises at Tenant's expense. This Lease shall
otherwise remain in full force and effect without apportionment to Tenant of any
portion of the award or damages.

     In the event of a termination pursuant to this Section, rent shall be
apportioned to the date of such taking.

     17.  Assignment and Subletting.  Tenant shall not have the right to:  (a)
          -------------------------                                           
assign or encumber its interest in this Lease or in the Premises; (b) sublet all
or any part of the Premises; or (c) allow any other person or entity to occupy
or use all or any part of the Premises without the prior consent of Landlord,
excepting however, that Tenant shall have the right to sublet the Premises or
assign this Lease, without Landlord's consent, to:  (d) a subsidiary, affiliate,
division or corporation controlling, controlled by or under common control with
Tenant; or (e) a successor corporation related to Tenant by merger,
consolidation, non-bankruptcy reorganization or government action. Landlord's
consent to any permitted assignment or subletting shall not be unreasonably
withheld or delayed.

     Tenant acknowledges that Landlord is in the process of converting from a
General Co-Partnership to a Limited Liability Company under Michigan statute,
and that following conversion, all rights and responsibilities of Landlord under
this Lease shall vest in such Limited Liability Company by way of assignment.

     18.  Default.  If Tenant shall abandon or vacate the Premises contrary to
          -------                                                             
the provisions of this Lease, or if default is made by Tenant in the payment of
rent, then Landlord shall have the right to re-enter the Premises and remove
Tenant and all persons therefrom and further, to terminate this Lease, at the
option of Landlord, subject to all applicable due process requirements.

     With respect to any breach by Tenant of any of its covenants under this
Lease other than the payment of rent, Tenant shall not be deemed in default
unless Tenant's failure to perform such covenant continues after Tenant's
receipt of written notice of default from Landlord for a period of seven (7)
days or such longer time as may reasonably be required to cure the default.
Landlord shall not be in default unless Landlord fails to perform its
obligations hereunder within a reasonable time, but in no event later than seven
(7) days after its receipt of written notice from Tenant specifying the nature
of any such non-performance; provided, however, that if the nature of Landlord's
obligation is such that more than thirty (30) days are required for performance,
then Landlord shall not be in default if Landlord promptly commences performance
within such seven (7) day period and thereafter diligently prosecutes the same
to completion.

                                      -9-

 
     19.  Landlord's Remedies and Default Cure.
          ------------------------------------ 

          (a) Following any default on the part of either party, the non-
defaulting party shall have the right to cure the default, at the defaulting
party's cost, and to have immediate recovery of said amount, with interest at
the rate of ten (10% per annum from the date the sum is paid by Landlord until
reimbursement.

          (b) Landlord shall be entitled to Court costs, attorney fees and
expenses, and any other amount necessary to compensate Landlord for all
detriment proximately caused by any default of Tenant.

          (c) Upon termination of Tenant's right to possession:

               (i)       Landlord shall have the right to recover from Tenant,
the fair market value of any unpaid rent earned at the time of termination of
the Lease.

               (ii)      The balance of any unpaid rent for the balance of the
Initial or Extended Term, as appropriate, following termination of Tenant's
right of possession and the computation of the amount determined under Section
19(c)(i), subject to paragraph (f) below.

          (d) Landlord shall have such other further rights and remedies as
shall be available at law or in equity.

          (e) All rights and remedies shall be cumulative.

          (f) Landlord and Tenant shall be required to mitigate damages in all
events.

     20.  Signage.  Tenant shall, at Tenant's sole expense, have the right to
          -------                                                            
place, construct and maintain on the Premises, one or more signs advertising its
business at the Premises and no other signs.  All signage shall comply with
state and local laws and ordinances.

     21.  Landlord's Entry on Premises.  Landlord and Landlord's authorized
          ----------------------------                                     
representatives shall have the right to enter the Premises at all reasonable
times for any of the following purposes:

          (a) To determine whether or not the Premises are in good condition and
whether Tenant is complying with its obligations under the Lease.

          (b) To perform any necessary maintenance or other restoration to the
Premises.

          (c) To shore the foundations, footings or walls of the building and
other improvements which are part of the Premises.

          (d) Except in the case of emergencies, Landlord and Landlord's agents
shall give Tenant at least forty-eight (48) hours oral or written notice prior
to entry of the Premises.  Any such 

                                      -10-

 
entry by Landlord or Landlord's agents shall comply with all reasonable security
measures of Tenant and shall not impair Tenant's operations more than is
reasonably necessary. During any such entry, Landlord and Landlord's agent shall
be accompanied by Tenant.

     22.  Subordination/Estoppel.  This Lease shall not be subject to or
          ----------------------                                        
subordinate to any ground or underlying lease or to any lien, mortgage, deed of
trust, or security interest now or hereafter affecting the Premises, nor shall
Tenant be required to execute any documents subordinating this Lease, unless the
ground Lessor, lender, or other holder of the interest to which this Lease shall
be subordinated contemporaneously executes a recognition and nondisturbance
agreement which (i) provides that this Lease shall not be terminated so long as
Tenant is not in default under this Lease and (ii) recognizes all of Tenant's
rights hereunder.  Further, Tenant shall have no obligation to attorn to any
successor-in-interest or ground lessor, nor to execute any documents evidencing
attornment, unless the successor-in-interest or ground lessor in question
assumes, in writing, all obligations of the Landlord under this Lease.  If
Landlord sells or otherwise conveys its interest in the Premises, Landlord shall
not be relieved of its obligations under the Lease accruing from and after the
effective date of such transfer, unless and until the successor assumes in
writing the obligations to be performed by Landlord on and after the effective
date of the transfer.

     Each party shall, within ten (10) days after notice from the other, execute
and deliver to the other, in recordable form, a certificate stating that the
Lease is unmodified and in full force and effect, or in full force and effect as
modified and stating the modifications.  The certificate shall also state the
amount of minimum monthly rent, the date to which rent has been paid in advance,
and the amount of any security deposit or prepaid rent.

     23.  Attorney Fees.  In the event either party commences an action against
          -------------                                                        
the other arising out of or in connection with this Lease, the prevailing party
shall be entitled to recover from the losing party, reasonable attorney fees and
costs of suit.

     24.  Surrender of Premises.  Upon expiration or termination of this Lease,
          ---------------------                                                
Tenant shall surrender the Premises to Landlord, together with all Tenant's
improvements and other alterations, except for such alterations which Tenant has
the right to, or is obligated to remove.

     If Tenant fails to surrender the Premises to Landlord as required, Tenant
shall hold Landlord harmless from any damages resulting from Tenant's failure to
surrender the Premises, including without limitation, claims made by a
succeeding Tenant resulting from Tenant's failure to surrender the Premises.

     25.  Holding Over.  If Tenant, with Landlord's consent, remains in
          ------------                                                 
possession of the Premises after expiration or termination of the Initial Lease
Term, or any extension thereof, or after the date in any notice given by
Landlord to terminate the Lease, such possession by Tenant shall be deemed to be
a month-to-month tenancy, terminable upon thirty (30) days notice given at any
time by either party.  All provisions of this Lease, except those relating to
Initial and Extended Terms, shall apply to any month-to-month tenancy.

                                      -11-

 
     26.  Consent of Parties.  Whenever consent or approval of either party if
          ------------------                                                  
required, that party shall not reasonable withhold such consent or approval.

     27.  Brokerage Fees.  The parties acknowledge that no broker has been
          --------------                                                  
utilized as a part of this transaction and as such, no brokerage fee or other
commission shall be paid as a part of this transaction.  Each party shall
indemnify and hold the other harmless from any and all liability arising out of
a breach of this Section.

     28.  Notices.  Any notice or demand required or permitted to be given
          -------                                                         
pursuant to this Lease shall be deemed effective only if in writing and
delivered either personally or by certified mail, postage fully prepaid, return
receipt requested, addressed as follows:

     If To Landlord:          Saginaw Video Associates
                              c/o James J. Shinners
                              5195 Hampton Place
                              Saginaw, Michigan 48604-9576

     If To Tenant:            Mr. Donald C. Schutt
                              Vice-President and General Manager
                              Concentric Network Corporation
                              4450 Fashion Square Boulevard
                              Saginaw, Michigan 48604

or to such other address as may be designated by either party, from time to
time, in writing and in conformity with the terms of this Section.  Any such
notice or demand shall be deemed to have been received:  (a) on the third (3rd)
business day after mailing, if notice was given by certified mail, return
receipt requested; or (b) upon delivery if notice was given by personal
delivery.

     29.  Binding Effect.  This Lease and the covenants herein contained shall
          --------------                                                      
be binding upon and inure to the benefit of the parties and their respective
successors and assigns.

     30.  Authorization.  The Officers executing this Lease on behalf of
          -------------                                                 
Landlord and Tenant represent that they are authorized to execute this Lease and
bind the respective Landlord and Tenant entities.

     31.  Covenant of Further Assurances.  The parties covenant, each with the
          ------------------------------                                      
other, and their respective heirs, administrators, representatives, successors
and assigns, that each party shall, at any time and at all times hereafter, upon
reasonable request, make, do, execute and/or deliver all such other and further
reasonable assurances, acts, deeds, documents and things as in the opinion of
competent counsel may be necessary or proper to effectuate the intentions of the
parties and complete this transaction.

     32.  Merger/Modification.  This Lease sets forth the entire agreement of
          -------------------                                                
the parties with regard to the lease of the Premises.  All prior agreements
between the parties with regard to the lease 

                                      -12-

 
of the Premises have been merged herein and shall be of no further force of
effect. No modification of this Lease shall be effective unless in writing and
executed by all parties.

     33.  General Construction.  This Lease shall be governed in all respects,
          --------------------                                                
whether as to validity, construction, capacity, performance or otherwise, by the
laws of the State of Michigan.  It is deemed by the parties that each has
executed this Lease in the County of Saginaw, Michigan, each party consenting to
the jurisdiction thereof.  Words of any gender in this Lease shall be held to
include the other gender and the words in the singular number shall be held to
include the plural when the context so requires.  Unless the context clearly
indicates to the contrary, time shall be deemed to be of the essence in the
interpretation of this Lease.  The titles or captions given to the Sections of
this Lease have been utilized solely for the purposes of convenience.  In no
event shall any such title or caption be deemed to be part of this Lease or
interpretive of any of its language or intent.  No provision of this Lease is to
be interpreted for or against any party because that party or that party's legal
representative drafted the Lease or its provisions.

     34.  Severability.  In the event any provision of this Lease is deemed
          ------------                                                     
invalid or unenforceable, said invalidity or unenforceability shall not affect
the other provisions hereof, and this Lease shall be construed in all respect as
if such invalid or unenforceable provision were omitted.

     35.  Hazardous Materials.  To the best knowledge of Landlord, (i) no
          -------------------                                            
Hazardous Material is present on the Premises or the soil, surface water or
groundwater thereof, (ii) no underground storage tanks are present on the
Premises; and (iii) no action, proceeding or claim is pending or threatened
regarding the Premises concerning any Hazardous Material or pursuant to any
environmental Law.  Under no circumstance shall Tenant be liable for, and
Landlord shall indemnify, defend and hold harmless Tenant, its agents,
contractors, stockholders, directors, successors, representatives, and assigns
from and against, all losses, costs, claims, liabilities and damages (including
attorneys' and consultants' fees) of every type and nature, director or
indirectly arising out of or in connection with any Hazardous Material present
at any time on or about the Premises, or the soil, air, improvements,
groundwater or surface water thereof, or the violation of any Laws, relating to
any such Hazardous Material, except to the extent that any of the foregoing
actually results from the release or emission of Hazardous Material on or about
the Premises during the term of the Lease by Tenant or its agents or employees
in violation of applicable environmental Laws.  As used herein, 'Hazardous
Material' shall mean any material which is now or hereafter regulated by any
governmental authority or which poses a hazard to the environment or human life.

                    *** INTENTIONAL DRAFTING PAGE BREAK ***

                                      -13-

 
                    *** INTENTIONAL DRAFTING PAGE BREAK ***

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

WITNESSES:                          SIGNED AND SEALED:

                                    SAGINAW VIDEO ASSOCIATES,
                                    a Michigan General Co-Partnership, d/b/a
                                    Saginaw Conference Center, Landlord


/s/ Dana M. Harris                  /s/ James J. Shinners
------------------                  ---------------------
DANA M. HARRIS                      By:  JAMES J. SHINNERS
(As To Landlord Only)               Its: Authorized Partner


/s/ Genevieve J. Nowak
----------------------
GENEVIEVE J. NOWAK
(As To Landlord Only)
                                    CONCENTRIC NETWORK CORPORATION,
                                    a Delaware Corporation, Tenant


/s/ Dana M. Harris                  /s/ Donald C. Schutt
------------------                  --------------------
DANA M. HARRIS                      By:  DONALD C. SCHUTT
(As To Tenant Only)                 Its: Vice-President and General Manager


/s/ Patricia A. Peters
----------------------
PATRICIA A. PETERS
(As To Tenant Only)



Prepared By:
SHINNERS & COOK
By:  James J. Shinners (P23942)
Attorneys at Law
5195 Hampton Place
Saginaw, Michigan 48604-9576
Telephone:  

                                      -14-

 
              ADDENDUM TO SAGINAW VIDEO/CONCENTRIC LEASE AGREEMENT
                         (MARCH, 1996 RENT PRO-RATION)
                          ---------------------------    



Monthly Rent (Existing Space):                     =    $9,667.00
-    11,600 square feet x $10.00 / 12                    
                                               
Per Diem (Existing Space):                         =    $  311.84
 -   $9,667.00 / 31                                      
                                               
03/11/96 - 03/31/96 (21 days)                      =    $6,548.64
$311.84 x 21                                       

PRO-RATED RENT DUE LANDLORD FOR MARCH, 1996:                  $6,548.64
                                                               ========
 
                                     *****

                                      -15-

 
                                   EXHIBIT A


                          Floor Plan of the Premises
                               [Graphic Omitted]

                                      -16-