The Slums, Sector 5 of Midgar. Who's living here is usually rather poor and not part of Soldier or the Turks, they are often just normal inhabitans. Monster often can be found down here too and as well there is a mall you can buy some stuff. Just don't forget, people down there don't really like the ones from the other sectors, just because they are the poorest. As Soldier you often need to have a lot of patience.