Bytopia is one of the Outer Planes in the Planescape setting for AD&D. Otherwise known as the Twin Paradises, it has two layers, Shurrock and Dothion, which are flat-earth environments of apparently unlimited extent, with a common sky-plane: that is, if you are in Shurrock and look up, above the luminescent haze which lights the plane, you will see Dothion, upside down. This is just one of the many mind-bending locales in the Planescape setting. The gnome gods live here, along with a grab-bag of others. This is the plane of Good Lawful Good, between Mount Celestia and Elysium.