The Inverted City is the colloquialism for the bottom half of the Public Sector of Titan Station. Known sections of the Inverted City are the Titan Elementary School, Solar Array Access areas, the Fuel Core areas, and the Hydrogen Processing areas.
The name "Inverted City" comes from Dead Space: Ignition. When you take Path B, Franco Delille and Sarah Andarsyn choose to enter the Inverted City. Going down the elevator, they talk about whether or not the people who live in the Inverted City call the Upright City the Inverted City. Sarah says they would because down is where your feet are.
It is unknown exactly what areas of the Sprawl are in the Inverted City or which elevators are able to access it. However, in Dead Space: Igniton, upon taking Path B, you can see the elevator that Franco and Sarah are taking from the outside. When it reaches the bottom of the Upright City, the elevator stops at a gear. The gear rotates the elevator upside down.
From the outside, you can see the elevator still going down, but you can see that the silhouettes of Franco and Sarah are upside down. This means that the gear switches the gravity in the elevator to match that of the Inverted City's. Interestingly, the top floor of any building in the Inverted City is actually the bottom-most floor in the Upright City.
While walking down a hallway in the Inverted City during Path B, Sarah tells Franco that she knows the Inverted City is not as densely populated as the Upright City, but she knows it should look more crowded than it does. This means that less people lived in the Inverted City than the Upright City.
During Dead Space: Ignition, it is reported that no reports of an outbreak are coming from the Inverted City. Later, it is discovered that the Inverted City was completely wiped out before the Upright City became infected. This might prove that the Inverted City was the first place the Necromorphs entered in the Public Sector. With the explosions on the Sprawl caused by Isaac's destruction of the Site 12 Marker, it is known that the Inverted City was completely and utterly destroyed.