Khazad-dûm is an ancient underground city and the greatest of the Dwarven realms in Middle-earth. Located beneath the Misty Mountains, it was renowned for its vast halls, intricate architecture, and rich deposits of mithril, a precious metal. The Dwarves, led by Durin, established this stronghold, which became a center of trade and craftsmanship. Over time, Khazad-dûm fell into darkness due to the awakening of the Balrog, a powerful creature that drove the Dwarves away. Eventually, the city was abandoned, becoming a haunted place known as Moria. It plays a significant role in The Lord of the Rings as a site of peril and adventure.