Feast your eyes upon M.C. Escher's Relativity from 1953.  You've probably seen some of his work before such as the fish that become birds or the two hands that are drawing each other.  He was a prolific artist who liked to create what I would call visual puzzles. Here in Relativity you have one such puzzle.  Where do the stairs begin?  What is the top?  What is the bottom?  The traditional approach to how space transitions on a 2 dymensional plain does not apply here.  Escher plays with those transitions and creates a complex visual world for us to explore.