Amazing optical illusions (or visual illusions)

check out this page, with (at the time of writing) 59 amazing visual illusions, and each one with an explanation of how it works, history of how/who discovered it, etc. very nice work put together

you can fint it here:

59 Optical Illusions & Visual Phenomena

I specially like these ones:
Frazer's Spiral

“Rotating Snake” Illusion

enjoy