The Coruscant underworld, lower levels, undercity, underground, underlevels, or Lower Coruscant, were terms used to describe the lowest regions of the city–planet of Coruscant, laid with a mixture of ancient and forgotten ruins from the planet’s prehistory along with modern-looking, crime-ridden venues and clubs. During the Clone Wars, a massive ventilation shaft offered access to the heart of the underworld.
Different regions and levels ranged from the merely seedy (such as the Uscru Entertainment District and 1313), progressively worsening as one descended, ending in areas of unending darkness populated solely by hypertrophied vermin and zombie-like devolved humanoids. The underworld’s streets were riddled with thugs and the walls and streets were home to all manner of strange creatures.
Most of the underworld rested more than a kilometer below the urban surface and city platforms. It was beneath some of the greatest skyscrapers in the galaxy and other closely-spaced spectacular buildings of Coruscant where few rays of light filtered through to the gloomy section known as the Underworld.