Moria

Khazad-dum was the greatest of the Dwarf realms in Middle-earth. Its vast and beautiful halls lay under the Misty Mountains. From its mines came great riches and it was the only source of the precious metal called mithril. But a Balrog slept in the deeps beneath Khazad-dum, and when it awoke the Dwarves were driven from their home. The halls of Khazad-dum were taken over by Orcs and other evil creatures and it became known as Moria, the Black Chasm, and was a place of fear and dread.