Exhibit 10.10.2
                                                                 ---------------


                            THIRD AMENDMENT TO LEASE

         THIS THIRD AMENDMENT TO LEASE (this "Third  Amendment") is entered into
as of the 1st day of September 1998 (the  "Effective  Date") by and between 6715
Kenilworth Avenue General Partnership ("Landlord") and Pathnet, Inc.
("Tenant").

                                 R E C I T A L S

         A.  Landlord  and Tenant are parties to that  certain  Lease  Agreement
dated August 9, 1997, as amended by that certain  Amendment to Lease dated March
5,  1998  and that  Second  Amendment  to Lease  dated  May 1,  1998  (together,
the"Lease").

         B. Landlord and Tenant desire to add certain  premises to the Lease and
make certain other  modifications  to the Lease as more  particularly  set forth
herein.

         NOW, THEREFORE,  in consideration of the mutual promises of the parties
and other good and valuable consideration,  the receipt and sufficiency of which
are hereby acknowledged, the parties hereby agree as follows:

1.                PREMISES.   From  and  after  the  Effective  Date,  the  area
                  described  in Exhibit  A,  attached  hereto  and  incorporated
                  herein,  located on the first floor of the building containing
                  the  Premises and  consisting  of  approximately  1,500 square
                  feet,  is  hereby  incorporated  into  the  Premises  for  all
                  purposes.

2.                RENT.  In  Paragraph 3 of the Lease,  as amended by the Second
                  Amendment  to Lease,  (i) the number  "$305,860.00"  is hereby
                  deleted and the number  "335,860.00" is inserted in its place;
                  and (ii) the number  "25,488.33"  is hereby  deleted,  and the
                  number "27,988.00" is inserted in its place.

3.                SECURITY DEPOSIT. As of the date hereof,  Tenant has increased
                  the  Security   Deposit  under  the  Lease  by  delivering  to
                  Landlord, and Landlord hereby acknowledges receipt of, the sum
                  of $2,500.  The parties  acknowledge that the Security Deposit
                  is currently $19,493.33.

4.                IMPROVEMENTS.    The   parties    acknowledge   that   certain
                  improvements will be constructed in the Premises pursuant to a
                  separate agreement.

5.                CAPITALIZED  TERMS.  All capitalized  terms not defined herein
                  shall have the meanings ascribed to such terms in the Lease.

6.                RATIFICATION.  Except as expressly  modified herein, the Lease
                  remains in full force and effect in accordance with its terms.

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         EXECUTED, under seal, as of the day and year first written above.

                                             LANDLORD:

                                             6715 KENILWORTH AVENUE
                                             GENERAL PARTNERSHIP


                                             BY:  /s/David Schaeffer
                                                ---------------------
                                                     David Schaeffer
                                                     General Partner

                                             TENANT:

                                             PATHNET, INC.


                                             BY:  /s/William R. Smedberg V
                                                 --------------------------
                                                     William R. Smedberg V
                                                     Vice President, Finance and
                                                          Corporate Development