Optical illusions are older than you think. The first optical illusions date back to 20,000 BC and took the form of cave sculptings. Nowadays they are found all over the place – on screens, in books ...

A truly mind-bending optical illusion is attracting attention over on Reddit – and I can see why, I've been staring at it for many minutes. The illusion looks simple at first – it's a set of stairs ...