They defy the rules of space, but captivate the mind. Most of these visions can't exist in the real world - only here, where artists play with perspective in the most remarkable ways. "An Impossible Staircase" goes up and down endlessly, with no highest or lowest step. How is that possible? And take a look at a very unique elephant: would it have trouble walking on its unusually-constructed legs? From the strangely three twisted rings in "Cosmic Wheels" to a meandering Celtic knit that you can try to untie, all the images are mind-boggling. Full colour optical illusions Fourth title in the Super Visions series of optical illusion puzzles Clever and fun puzzles.