Gran Pulse

Gran Pulse Versions
Final Fantasy XIII
Final Fantasy XIII-2

Gran Pulse is the name of the world in Final Fantasy XIII and its sequels. It's unknown how long the world has had inhabitants, but evidence suggest several thousand years of advanced civilization (albeit all in ruins in the current day), and at least on one timeline the last of the civilization would extend until around 700 years in the future of XIII-2's events, after which all or most living things in the world were destroyed.

Gran Pulse has an unknown number of natural moons, as well as one artificial one known as Cocoon, the last of them relatively low in the skies. While advanced civilizations on the ground withered and died away, the civilization on Cocoon (a portion of the original Pulsians who moved up to the skies) flourished and advanced. Cocoon fell from the skies the end of the original game, but was thereafter held up by a Crystal Pillar, rendering the moon partially habitable still. It bears noting that the inhabitants of Cocoon lived on its inner surface, not outer surface.

Not too much about the geography of Gran Pulse is known. There are great mountains, great plains, and quite likely great all other types of geographical areas. Ancient metropolises litter the landscape. The only current-day (and future) city still alive with inhabitants was built around the Crystal Pillar.