Utumno was the first fortress of Morgoth in the far North of Middle-earth before he destroyed the Two Trees of Valinor and before even the First Age.

Utumno was delved very deep into the flesh of the Earth. Here Morgoth built his first of many dungeons and deep halls of obsidian, fire, and ice. Utumno had many hundreds of caves, tunnels, corners, and rooms, which allowed many things to remain hidden and secret for a very long time.