The Free On-line Dictionary of Computing (30 December 2018):

GNU archive site
GNU mirror site

    The main GNU FTP archive is on gnu.org but copies
   ("mirrors") of some or all of the files there are also held on
   many other computers around the world.  To avoid overloading
   gnu.org and the Internet you should FTP files from the machine
   closest to yours.  Look for a directory like /pub/gnu,
   /mirrors/gnu, /systems/gnu or /archives/gnu.

   GNU Project FTP server (https://ftp.gnu.org/).

   (2014-12-04)