Brass Citadel

The Brass Citadel is a structure within the Realm of Chaos, towering over the ageless desolation of Khorne's realm. The walls of this unholy bastion are jagged, thick with crusted blood and hung with gibbets and gallows. The moat of the brass citadel is filled not with water, but with the boiling blood of Khorne's victims. Iron gargoyles snarl from every parapet, hatred flashing in their eyes and molten metal boiling in their bellies. Flesh Hounds prowl the space between the outer walls and the keep, gnawing at ancient bones and longing for fresh meat.

Khorne himself dwells within a great vault at the black heart of the citadel's central keep. Eight iron pillars vanish into the ebon gloom to shoulder the inconceivable weight of the throne room's ceiling. Each pillar is inscribed with one of the commandments of Khorne, edicts that speak to the unholy virtues of rage, martial skill and defiance. In the center of the room the Blood God sits upon a mighty throne of brass rooted atop a vast mountain of skulls.

In the very direst of need, when his armies are overwhelmed and his citadel beset, Khorne rises from his throne, his armoured footfalls shaking the Realm of Chaos to its core.

Source
1 Warhammer Armies: Daemons of Chaos (8th Edition)

1a -- pg. 8

1b -- pg. 9