Moria is a fictional underground city from J.R.R. Tolkien's Middle-earth, primarily featured in "The Lord of the Rings" and "The Hobbit." It was originally a dwarven kingdom known for its vast halls and rich deposits of mithril, a valuable metal. Moria is also referred to as Khazad-dûm and is located beneath the Misty Mountains. The city fell into darkness after the dwarves awakened a fearsome creature known as the Balrog. This led to the decline of Moria, making it a dangerous place filled with remnants of its former glory. The Fellowship of the Ring travels through Moria in their quest to destroy the One Ring.