The Café Wall Illusion is a famous optical illusion composed by black and white squares where perfectly straight, parallel horizontal lines appear to be tilted.

Your brain is tricked by a specific combination of geometry and contrast. Three exact criteria must be met to trigger the effect:

• Staggered Tiles: The black and white squares must be shifted by half a tile width.
• Mortar Lines: The horizontal divider lines must be visible.
• High Contrast: The squares must have strong alternating dark and light values.

The pattern was first documented in 1898 as the Münsterberg illusion. It was later rediscovered in 1973 by researcher Richard Gregory, who noticed the striking effect on a tiled wall of a café in Bristol, England.

You can manipulate it below. Move the slider back and forth to create the illusion.