These are all perfect squares, but the lines seem to bend because of their position. The first time this illusion was spotted was on the outside wall of a café in Bristol. The wall was covered with black and white tiles, showing the same result as seen here. This is also called a Muensterberg figure. Derived :Café wall illusion (animated) :: Bristol Café wall Sites :An Analysis of the Cafe Wall Illusion Number of ratings : 42.
Paradox Box Not really a book but a collection of visual playstuff in a box.
The Art of Optical Illusions Al Seckel has done a wonderful job of assembling this great collection of visual illusions. It is lavishly illustrated - mostly one illusion per page - with the majority in full color, allowing the reader a generous view of the eye-teasing pictures.
Little Giant Book of Optical Illusions With about 300 images, this book covers the most basic illusions you'll ever come across.
How to Really Fool Yourself This book features over 70 activities to fool all five senses. Each illusion is followed by a fascinating "Why You're Fooled" section that explains the science and history behind the "magic."
The Great Book of Optical Illusions A lot of the best illusions of this site in full color.