"Relativity", 1953 (lithograph) by M.C. Escher This is perhaps Escher's best-known print on the theme of relativity. It also is a fine example of Escher's focus on unusual, and often conflicting, points of view.
Dice optical illusion The dice appear to form an impossible triangle. If the position of the camera was to shift slightly, you would see that in reality the 'triangle' is actually created by three lines of dice arranged in the shape of the letter 'Z'