Details: This poster is of M.C. Escher's Belvedere. It shows a belvedere built with impossible dimensions. On the floor of the lower platform, that is to say indoors, stands a ladder which two people are climbing. But as soon as they arrive a floor higher they are back in the open air and have to re-enter the building.
M.C. Escher was known for his often mathematically inspired works which feature impossible constructions, explorations of infinity, and tessellations. His works include Dolphins, Castrovalva, Bridge, Atrani, Still Life with Spherical Mirror, Hand with Reflecting Sphere, Regular Division of the Plane, Still Life and Street, Metamorphosis, Reptiles, Magic Mirror, Three Spheres, Another World, Drawing Hands, Stars, Curl-up, House of Stairs, Puddle, Gravitation, Relativity, Convex and Concave, Three Worlds, Belvedere, Ascending and Descending, Waterfall,