Exhibit 10.13

                                 PROMISSORY NOTE

$70,000,000.00                                                    March 30, 2000


         FOR VALUE  RECEIVED,  PATHNET  TELECOMMUNICATIONS,  INC., a corporation
duly  organized  under  the laws of the  State of  Delaware  (the  "Purchaser"),
promises to pay to Pathnet,  Inc., a Delaware corporation,  at 1015 31st Street,
Washington,  DC 20007  ("Seller"),  or at such other place as the holder of this
Note may from time to time designate in writing, the principal amount of SEVENTY
MILLION  AND NO/100  DOLLARS  ($70,000,000.00),  together  with  interest on the
unpaid  principal  amount  of this Note  computed  from the date of  Closing  as
defined  in  the  Assignment  and  Acceptance  Agreement  (the  "Assignment  and
Acceptance")  by and between  Purchaser  and Seller,  dated the date hereof,  as
amended from time to time, until the entire indebtedness is paid, at the rate of
twelve and one quarter percent (12-1/4%) per annum. The principal amount of this
Note shall be due and payable on March 31, 2010. Accrued interest  calculated on
the outstanding  principal  amount as described above shall be payable yearly on
the last day of each year  commencing with the year ended December 31, 2000. All
payments  hereunder  shall be made in  lawful  money  of the  United  States  of
America.

         The unpaid  principal amount of this Note may be prepaid in whole or in
part at any time.

         The entire  unpaid  principal  amount of this Note or any  extension or
renewal hereof,  together with accrued interest and all charges owing under this
Note or the Assignment and Acceptance,  shall immediately become due and payable
at the  option of the holder of this Note,  without  demand or notice,  upon the
occurrence of any of the following Events of Default:

         (a) Purchaser  fails to pay the principal  amount of this Note when the
same  becomes  due and  payable  (whether  on the date on which  such  principal
becomes due or upon acceleration or otherwise); or

         (b)  Purchaser  fails to pay any interest when the same becomes due and
payable  hereunder  and such failure to pay continues for ten (10) business days
after the date on which such payment of interest was due.

         If this Note, after maturity,  whether by acceleration or otherwise, is
placed in the hands of an attorney  for  collection,  whether suit is brought on
the same or not,  Purchaser  shall pay to the holder of this Note all attorneys'
fees as are incurred for the purposes of collection hereof.


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         Each  Obligor  under this Note  (which  term shall  include all makers,
guarantors,  endorsers and other persons assuming  obligations  pursuant to this
Note) hereby waives presentment,  protest,  demand, notice of dishonor,  and all
other  notices,  and all defenses and pleas on the grounds of any  extensions of
the time of payments or the due dates of this Note, in whole or in part,  before
or after maturity, with or without notice. No renewal or extension of this Note,
no release or surrender of any  collateral  given as security for this Note,  no
release  of any  Obligor,  and no  delay  in  enforcement  of  this  Note  or in
exercising  any right or power  hereunder,  shall  affect the  liability  of any
Obligor.

         This  Note  may not be  changed  orally,  but only by an  agreement  in
writing  which is signed by the party  against whom  enforcement  of any waiver,
change, modification or discharge is sought.

         IN WITNESS WHEREOF,  Purchaser has caused this Note to be duly executed
on its behalf as of the date set forth at the beginning of this Note, as the act
and deed of Purchaser.


                                PATHNET TELECOMMUNICATIONS, INC.


                                By: /s/ Mary McDermott
                                   -------------------------------------
                                Name: Mary McDermott
                                Title: Senior Vice President, General Counsel
                                        and Secretary




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