Um'taran

Um'taran was the gigantic, mostly subterranean fortress of the Dark God, built first during the Dawn Age by the Flesh-Angels and then expanded during the First Wars.

Description
Um'taran was built deep into 'the flesh of the earth' below the northern edge of the Blacklace Mountains as they swing west. The first line of defence consisted of an enormous curtain wall built from black iron and obsidian, which guarded the Great Gate, the entrance to the fortress. They stood at almost 200 feet tall and were so thick that no power of sorcery could breach them. The first gate was built into an enormous guardhouse so squat and thick-set that it was impossible to destroy by force. The mines and pits within stretched for countless miles under the ground until they reached the Nethermost Pit: the lair of the Dark God. It was considered to easily be the greatest fortress in recorded history.

History
Um'taran was first constructed by the Flesh-Angels once they had escaped from the Old Ones. The Dark God took them under his control and bid them create for him hordes of twisted creatures he called his Weapon Races: the Keth, Trolls and other obscene creatures. The pits below it were steadily expanded until they went hundreds of miles deep into the ice and basalt. During the First Wars, Um'taran was besieged by the Eldar for a century before its walls were broken and the caverns within scoured of all life. But the Dark God survived, and during the First Cataclysm raised another curtain wall, this one far larger and greater than the first. Throughout the conflict, no mannish army ever breached the walls, and it remained mostly intact for millennia afterwards.

During the march of the Host of Man to the dread fortress in 4145, the Keth hordes were withdrawn into the deepest caverns. The famed curtain walls were indeed breached; however, the Slave Gate slammed shut and the hordes prepared for siege. The Host encamped outside the Gate, unaware that hundreds of thousands of Keth were marching on them from their rear. The Dark God was then summoned, and the Host destroyed.

Upon the Dark God's final death in 4176, Um'taran was abandoned as his creatures perished. It was never again inhabited and the battlements remained ruined.