The catacombs are a network of tunnels which run under the marketplace. Most of the catacombs are occupied by the Cats of the Cressida Lock, save for the parts that are too narrow, filled with concrete, too close to the sewers, or infested with rats and crammed with rubbish.
The road is mentioned to be an endless concrete pathway with huge machines running on them. It circles around the marketplace, on the far side of the park, and right up to the edge of the terraces upstream. The machines run very quickly and can kill a cat with ease. There was a case of a death on a road.
The Cats of the Cressida Lock have a unique naming system. Every catling is to be given a normal name, such as Ria. When they earn their first accomplishment or catch their first prey, they will earn a suffix. For example, if a cat hunts a mouse, they might be known as "[name], Slayer of Mice" or something that gives the same effect. This honor is marked by a short ceremony at the following full-moon meeting.
When a cat earns greater respect, a second suffix is added at the end of the title, being either courageous for a hunter or fighter, and sagacious for a thinker, and for anyone else who is respected despite not being able to hunt or fight. (Examples: Arabella the Courageous, Fink the Sagacious)
The title Pirrup is only earned by high-ranking cats who have done something incredible to contribute to their kin. For example, Pangur earned the title "Pirrup" by defeating the previous chef in open combat.