The Fortress of Utumno

Utumno, also named Udûn, was the first fortress of Melkor in the far north of Middle-earth, before the First Age.

Utumno was carved very deep into the flesh of the Earth by Melkor himself. Through time, much of the subterranean domain had been cast from obsidian, fire, and ice beneath it.

During the time of the Lamps, before the First Age, Melkor first dug the great Pits of Utumno deep beneath the mountains of the North. The fortress was constructed here in the Iron Mountains (over one thousand miles from the later location of Angband) where the light of the lamps did not reach.[1]

 
Here Melkor gathered to him all the evil powers of the World. Creatures were also bred here such as trolls, "made in mockery of the Ents" as stated by Treebeard. Cruel spirits, phantoms, wraiths, and evil demons stalked the halls of Utumno and haunted the surrounding forests.

From Utumno, Melkor poisoned and interfered with all the Valar's work done during the Spring of Arda. Soon afterwards, Melkor and his servants waged his war and struck down the lamps, ruining the world, and forcing the Valar to move further west to the continent of Aman.

Utumno endured for millennia well into the early years of the Elves at Cuiviénen during the Years of the Trees. Taking advantage of the new arrivals, Melkor captured some of them and thus, the hideous race of Orcs was bred. Knowing that Melkor would continue to be a blight upon the world, the Valar decided to protect the Elves by ending his power in the north. Amidst the sounding of the trumpets, the Valar came out of the west, and after the Battle of the Powers Utumno was besieged and destroyed in YT 1099, and Melkor was chained for about three thousand years.