Location from Attack on Titan by Hajime Isayama
The innermost wall. Where the wealthy, the powerful, and the royal government shelter behind two walls' worth of buffer zone. Safety purchased by other people's deaths.
Wall Sina is where you live if you can afford to never think about Titans. The interior is a world apart from the frontier districts — clean streets, functioning institutions, nobles who consider the Survey Corps a waste of tax revenue. The royal government operates from within Sina, or at least the puppet government does. The real power — the Reiss family, inheritors of the Founding Titan — lurks beneath the surface, literally and figuratively. The Military Police maintain order here, which mostly means protecting the interests of the elite and making sure uncomfortable truths stay buried. The Underground City festers beneath its streets, a shadow version of the prosperity above. Sina's residents tell themselves they're safe. They are the least safe of anyone, because they have the most to lose when the truth comes out.
Also known as: Sina, the inner wall, the interior