Beautiful Mathematical Images My Maths department is re-branding itself, and we've been asked to find suitable images for the departmental sign. Do you have a favourite mathematical image that could be used for the background of an A1-sized sign?

Penrose tiling, an example: 

http://en.wikipedia.org/wiki/Penrose_tiling
Or any basic first year theorems (or more advanced) theorems like MVT, Taylor, BW, cardinalities, ordinals etc, in nice fonts or even as sculpture.
Complex but symmetric 3D objects like the Wolframram Alpha star for example, see also George Hart.
