Citadel

The Citadel is a Forerunner urban habitat located inside the shield world Trevelyan. It served as the base camp for Blue Team and the other human survivors of the Battle of Onyx for the majority of the time they spent stranded in the shield world. It consisted of numerous buildings; towers, multi-story blocks, domes and various sprawling low-rise structures, all made of characteristic silver-gray Forerunner material, stretching as far as one could see. The interiors were pristine and perfectly clean due to constant maintenance by the shield world's resident Huragok, and had gravity lifts which could be used to access different floors. The buildings had no solid furniture; instead, in typical Forerunner fashion, they could generate hard light furnishings at will. Many of the doors had ornately decorated frames.

List of appearances

• Halo: Glasslands (First appearance)