Release Message:  Two arches are placed on top of each other. They are similar in size, but not the same. The inner radius of the upper arch is the same as the outer radius of the lower arch.

Description:  The oldest reference to this illusion can be found in The World of Wonders, an 1873 book about curiosities of nature, science and art. The Jastrow illusion has been compared with other optical illusions, such as the Fat Face illusion, the Leaning Tower illusion and the Ponzo illusion.