Undercity

An undercity is the sum of the subterranean areas of a city, or more broadly, any shady areas frequented by thieves and other criminals, whether above-ground or not. The most prominent undercity is the one under Nibennium, which has even spawned its own subculture and language. Other notable locations include the Ratway of Riften, the subterranean ruins of Markarth, and the Black Kiergo of Senchal.