The Inverted City was 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" came from Dead Space: Ignition. When you took Path B, Franco Delille and Sarah Andarsyn chose to enter the Inverted City. Going down the elevator, they talked about whether or not the people who lived in the Inverted City called the Upright City the Inverted City. Sarah said that they would because down was where your feet are.
It was 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 reached the bottom of the Upright City, the elevator stopped at a gear. The gear rotated 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 meant that the gear switched the gravity in the elevator to match that of the Inverted City's. Interestingly, the top floor of any building in the Inverted City was actually the bottom-most floor in the Upright City.
While walking down a hallway in the Inverted City during Path B, Sarah told Franco that she knew that the Inverted City was not as densely populated as the Upright City, but she knew that it should look more crowded than it did. This meant that fewer people lived in the Inverted City than the Upright City.
During Dead Space: Ignition, it was reported that no reports of an outbreak are coming from the Inverted City. Later, it was 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 that the Necromorphs entered in the Public Sector. With the explosions on the Sprawl caused by Isaac's destruction of the Site 12 Marker, it was known that the Inverted City was completely and utterly destroyed.