The Citadel is the Brotherhood of Steel's main base in the Capitol Wasteland. It used to be the Pentagon. It is were Cywren Caster escapes to after the Enclave took over the Project Purity. This place is were we first seen Daxius's new form, Liberty Prime. It is divided into several sections: The Courtyard where the Initiates train and sleep. The Laboratory where the Scribes work, the Armoury is located and where Daxius' is usually located. A Ring where the Archives, The Great Hall and the Lyons' Pride Den is located. B Ring where the Infirmary, where Cywren wakes-up in after activating the Purifier, and the sleeping quarters for the Knights, Scribes and Elder Lyons is located. Outside Brotherhood Paladins and turrets patrol for Super Mutants and other threats.