Möbius Strip, Maurits Cornelis Escher, 1961
At first sight this depiction by Escher seems fairly straightforward. Upon closer inspection, however, it appears to be a single strip rather than two continuous ones: brown on one side, and green on the other. The twists make it look like two intertwined threedimensional loops. Escher is actually illustrating a Möbius Strip, a mathematical spatial construction.