Midgar

Gaia's land area is comprised of three major landmasses. The Eastern Continent is where the game begins. To the west across the ocean is the Western continent and the Northern continent lies to the north of both of them. Smaller inhabited landmasses lie to the west and south of the main continents.
Midgar is the de-facto capital of Gaia, controlled by the Shinra Company. It sits in the middle of a large plain on the northwestern corner of the eastern continent. The area around the city has become drained, lifeless and polluted as a result of the use of Mako reactors. The city's prosperity was due to the abundance of Mako Energy in the vicinity, and the reactor complex meant that there was no vegetation within the city or in close proximity to it, with exception to the church where Aerith and later two children tend to flowers. The area where the city stands also appears to be in a state of constant darkness even during daylight hours. This was made obvious when the Sister Ray was fired; at that moment, it was dark in Midgar, but clearly daylight where the Mako beam struck the Diamond WEAPON (just outside the city). Whether or not this constant darkness is also related to the use of Mako reactors is unclear, although by the time of Advent Children, after the city had been destroyed and mako generation had ceased, daylight had returned to Midgar.
The city of Midgar is a circular plate elevated 50 meters above the ground and supported by both a central pillar and a system of smaller columns. A network of maintenance platforms are also suspended beneath the plate. Commercial and residential complexes, as well as recreational facilities such as bars and theaters are located on the plate. The plate itself is divided into eight numbered sectors with each sector punctuated by two walls and a Mako reactor. Each of these sectors once had a name, but no one in Midgar remembers them. The Shinra Company headquarters, Sector 0, is located at the center of the upper plate, and serves as the tallest structure in the city with 70 floors, the top ten of which are restricted access. There also appears to be a built-up ring outside the main perimeter of the city. The upper plate would remain incomplete for the entirety of its history.