.Cafe Wall Illusion
What to see and do: Click and drag the box at the bottom to see that the rows of blocks are straight and not crooked like it appears. Drag the block to find out where the illusion works the best.
What's happening: The illusion only works when the black boxes are partly lined up. The explanation for this illusion is very complicated. If you would like to read one explanation, visit http://www.brainconnection.com/teasers/?main=illusion/cafe-wall
Credit: This illusion was discovered by Dr. Richard Gregory. He noticed this pattern on a cafe wall in Bristol, England.