What is the Café Wall Illusion?

The Café Wall Illusion is a geometrical-optical illusion, which appears on the “Workhouse Café” at the bottom of St Michael’s Hill. It has come to be a great Bristol Landmark. The illusion is made of green and cream tiles that, although perfectly straight and parallel, appear to be long wedges. A quick Google search reveals many images of the Café Wall Illusion – not only on café walls, but on large buildings across the world.

This illusion greatly intrigued Richard Gregory FRS CBE, professor of neuropsychology who worked nearby in his Brain and Perception Laboratory of the University of Bristol University. Richard Gregory wrote several books on vision and was especially interested in explaining illusions. In order to understand this mysterious illusion, he first built a wooden chessboard where every other row could be slid across. He found that there was no illusion if there was no gap between the rows; so he had to add a metal strip, then there was a good wedge illusion which could reversed by moving the sliding tiles. More experiments were done in his lab and it became rather famous.

Why we need your help

A few years ago there was a traffic accident at the bottom of St Michael’s hill; a bus crashed into the wall, which broke off some tiles. These Victorian-era tiles and the original Café Wall Illusion is at risk of being lost forever: the tiles now lie cracked and broken and are in desperate need of repair.

Today we’re asking for your help. Your support will help repair and replace the tiles and sections of the wall. Specialist tiles are needed to match the exact colouring and ensure the illusion is retained.

Can you help us to mend this unique Bristol Landmark, so that it will live on at bottom of St Michaels Hill in Bristol, to be appreciated by those that pass by?