Coruscant Underworld

The Coruscant underworld, also called the lower levels or undercity, were the levels underneath the surface structures of the planet Coruscant. Skyscrapers towered above the surface structures, the highest livable level on Coruscant being Level 5127, but under the surface structures the levels of Coruscant descended down all the way to Level 1 which was deemed uninhabitable. The various levels of Coruscant were accessible by huge portals that also served as ventilation shafts. Covered by the surface structures, sunlight did not reach the lower levels leaving them in a perpetual state of darkness illuminated only by artificial lights for thousands of years.