Angband, the Fortress of Morgoth

Angband, also known as the Iron Prison, was the ancient fortress of Melkor in the depths of the Iron Mountains that was built after the destruction of the Two Lamps as an arsenal of Utumno, but later it became the Dark Lord's primary stronghold from which he constantly tried to dominate Arda. Angband was finally destroyed by the Host of the West at the conclusion of the War of Wrath.