An earlier posting (Maps have been lying to you) showed the effect that the Mercator map projection has on the way we perceive the world. The challenge of portraying on a flat surface the essentially spherical shape of our planet has puzzled cartographers for centuries. The job cannot be done without distortion and this is demonstrated beautifully on this page of map projection transitions. The ellipses are Tissot indicatrices that describe distortion at a single point.
Photo by anna_t