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 4, 1999 in Amendment No. 2 to
the Registration Statement (Form S-4 No. 333-71129) and related Prospectus of
Metromedia Fiber Network, Inc. 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
April 9, 1999