The complete data set is 55 gigabytes in size.  Each of the almost 7,000 color anatomical cross sections is 7 megabytes.  The data set is made up of almost 7,000 files, each file containing one of the cross sections.  The data set can be downloaded from a password protected FTP site via the internet.

     It was clear to us right from the start that files of this size would take considerable time to download over the internet.  For this reason the data set was also made available on digital tape.  But for many people, FTP over the internet was the preferred mode of access.  When licensees outside of North America tried to download even a single 7 megabyte file it was obvious that this would require an heroic effort.  The problem was the available bandwidth across the oceans.  It was at that point that NLM was approached by colleagues in Europe, Asia and South America who suggested that we authorize mirror sites for our Visible Human® data sets at key communications sites outside of North America.  They also volunteered the communications links, computers and disk storage space necessary to build the mirror sites at no cost to the NLM.

      The "VISIBLE HUMAN DATASET - MILANO MIRROR SITE^®" (VHD-MMS) (Figure1) is an initiative of cooperation promoted between the National Library of Medicine and the Politecnico di Milano. It has been built up with the technical help and the administrative assistance of CILEA. This is the more than 25 y.h. Consortium established, among the universities of the Lombardia region, for organizing and delivering services of advanced calculus.
 
      The "VISIBLE HUMAN DATASET - MILANO MIRROR SITE^®" has the mission of providing the Continental-Europe users of the "Visible Human® Data Set"-i.e. the 55-Gigabytes largest bank of multimodal bioimages we have never seen-with the best possible services, better than those available while crossing the Atlantic Ocean on Internet. To do so, it "mirrors", i.e. it repeats, in Milano the entire "Visible Human® Data Set", originally made available at the Bethesda main-site of the National Library of Medicine only. This effort has been supported from four non-competitive multinational sponsors, two of them with head home in USA and two in Europe. This way NLM should reduce its own FTP traffic, from countries nearly the existing mirror site.
     The knowledge if mirror initiatives have produced, or are still producing, this effect become an imperative, both for NLM and single mirror sites.