Layer of the eighteenth floor with a rickety wooden floor, sitting above the Hunting Grounds and Larracos.
Studying the funnel walls of Larracos and realizing they are nothing more than a hole in the ground rather than the walls of the volcano, Carl turns the floor's construction over in his mind. The Over City had a wooden floor that seemed downright rickety in places. The Hunting Grounds were jungle with solid, physical ground and even a deep river running through them — yet supposedly if one spent too much time digging up there, one would break through and fall into the Larracos area below.
Carl concludes it is all fake, all game setup, and the Larracos area is the same. But he decides it is still important to know exactly how all of it works, since the geometry of the layers is going to matter once the fighting starts.
A city built on a wooden floor that feels downright rickety in places.
The uppermost layer of the eighteenth floor's stacked construction.
Also appears in books you've already read — spoiler-safe to their endings: