EXHIBIT 23.1
 
                        CONSENT OF INDEPENDENT AUDITORS
 
We consent to the references to our firm under the captions "Summary
Consolidated Financial Data," "Selected Consolidated Financial Data" and
"Experts" and to the use of our report dated March 16, 1998 relating to the 1997
and 1996 financial statements of Metromedia Fiber Network, Inc. in the
Registration Statement (Form S-4) and related Prospectus for the registration of
$650,000,000 of its 10% Series B Senior Notes due 2008.
 
                                          /s/ Ernst & Young LLP
                                          Ernst & Young LLP
 
New York, New York
January 22, 1999