If you walk far enough, you'll fall off the edge of the world. For this world is not round, but flat. What lies beyond the edge? No one knows. In ancient history, many cultures believed the Earth was flat. Certainly the curvature is so slight that it wasn't until the Greeks that the spherical Earth theory took hold (contrary to popular belief, Columbus didn't have to try and convince people that the earth was round). A subtrope of Bizarre World Shapes. Not be confused with an animation called Flatworld. Examples of Flat World include: