Closet

A closet is a single square located behind a door. Often the door is a secret door, and sometimes has ad aerarium written in the dust outside, indicating the closet contains a vault teleporter.

Sometimes closets are generated without doors leading to them. The only way to get to these is for a corridor to be generated adjacent to them, or to teleport in. If there is a scroll inside these closets, it is almost certainly a scroll of teleportation. If you find yourself inside a closet with no means of exit or escape, praying can get you out.

Monsters can be generated inside closets just like on any other square.