Useful links

Illusions and impossible figures
An old web project about illusions by Al Seckel (English)
Very large collection of images with illusions and impossible figures. Many pictures by famous artists. (English and dutch languages)
A large site about illusions and impossible figures with animations and Java-applets. (English)
Large collection of impossible figures (Hungarian language)
Large website about illusions (French)
There's kindred site about fictitious figures at
Large collection of illusions and impossible figures including (Russian)
A site about illusions - an english variation of the site above (English) NEW
Blog about optical illusions by Brad Honeycutt

M. C. Escher
Big gallery with Escher's artworks, competitions, electronic shop etc. (English)
Official M. C. Escher website (English)
The one of the biggest collection of Eschers's artworks in Internet (English)
Detailed Escher's bigraphy (English)
Collection of rare Escher's artworks 

Oscar Reutersvard
Much original images by Oscar Reutersvard. (Italian language)
Big collection of Escher's, Sandro del Prete's and Reutersvard's images. (English)
Few images by Reutersvard. (Swedish language)
A site with various Reutervärd based images. (English)

Sandro del Prete
Official Sandro del Prete's site. (English)
Leonardo On-line gallery. Collection of images by Sandro del Prete, Jos de Mey, Istvan Orovits and others. (English)

Istvan Orosz
Istvan Orosz's website. (English)
Three artworks by Orosz with well quality. (Hungarian language)
Extensive collection of images by Orosz. (English)

Miscellaneous (NEW)
Official website of Irvine Peacock (English)
Website of russian artist Dmitry Rakov. (Russian and english languages) (NEW)
Website of russian artist Igor Achkasov (Russian and english languages)
Website of german artist Guenter Albrecht-Buehler (English)
About mathematical art. (Dutch language)
A small book about impossible figures. (English and german language)
Article at electronic magazine "Computer News On-line" about illusions. (Russian language)
Website focused on how to learn magic.