Escher gallery
Searchable gallery of m.c. escher's amazing artworks. download m.c. escher desktop patterns and wallpapers.
http://www.eschergallery.com/
Escher in het paleis
Escher in het paleis
http://www.escherinhetpaleis.nl/
M.C. escher
M.C. escher
http://www.mcescher.nl/
Universiteit Leiden
This project is an initiative of Hendrik Lenstra of the Universiteit Leiden. and the University of California at Berkeley. Bart de Smit of the Universiteit Leiden runs the project. Their joint paper is the main resource for this site.
http://escherdroste.math.leidenuniv.nl/