See also optical illusions and patterns/textures.
Contributed by George Triantafyllakos
Contributed by Sandoll Inc.
Contributed by Jorge Iván Moreno Majul
Contributed by Marçal Prats
Contributed by Florian Hardwig
Photo(s) by Buro Destruct on Flickr.
Contributed by Swiss Typefaces
Contributed by Edgar Walthert
Contributed by Type@Cooper
Contributed by Milos Mitrovic
Contributed by 205TF