Undermountain

Undermountain is a vast labyrinth of caverns in the Underdark under the area of Waterdeep. It was created by Ed Greenwood in 1975. This was the first dungeon for his fledgling Forgotten Realms campaign setting, and he used the Undermountain in both his Dungeons & Dragons and Advanced Dungeons & Dragons games. In 2003, Waterdeep and Undermountain served as part of the setting for the Neverwinter Nights computer role playing game expansion, Neverwinter Nights: Hordes of the Underdark.