Before the Great War of the Republic and the Confederation, the nations of Terra had come together to form one giant underground bunker. This bunker would be called Level 8. The name came from how many layers of the Earth were cut into to make this in the thousands. In simple terms, it was 8000 feet under the ground. There was slight dispute over the name but the leaders settled with Level 8 because it sounded more appealing.
Level 8 is all throughout the main lands of Terra and is one giant apartment complex. There's rumored to be about enough room to fit double the current Terran population down there, which is 2.5 billion, as of now. Level 8 is not just used for emergency scenarios but some people live in the underground complex normally. The people who live here are just slightly better off than those from the Slums or Terra. Like the Slums there's violence and without immediate government involvement for all cases, it's easy to see why.
The people of Level 8 work on Terran sewers and mines. They typically don't go to the upper levels and have grown accustom to life underground and in the darkness of the shadows.