Citadel

From the White Wolf Wiki, the most complete White Wolf reference

The visible Heart of a Necropolis and the visible symbol of the Hierarchy, a Citadel is a massive haunt, usually constructed around one or more buildings reinforced with soulsteel doors and other accoutrements. Citadels are specifically designed to survive a Great Maelstrom, and are consequently built as heavily reinforced and generally hideously baroque fortresses.

A Citadel will also serve as the administrative nerve center for the Hierarchy; as a result, they are usually used as a communal haunt by the legions of bureaucrats which keep Stygian society running.