The Citadel

The Citadel is the heavily defended headquarters of the Brotherhood of Steel in the Capital Wasteland in 2277. It is built into and beneath the ruins of the Pentagon, the pre-War headquarters of the U.S. military. Located on the west end of Francis Scott Key Bridge, northeast of Arlington Library, it initially consists of four interior sections.

Background
The ruling council of the Brotherhood of Steel, based in the Lost Hills bunker in Southern California, decided to send a contingent of soldiers to the East Coast to recover any and all advanced technology from Washington, D.C. and The Pitt, as well as to investigate reports of super mutant activity.

The Pentagon, as feared, was largely destroyed. However, its sub-levels remained intact and contained enough pre-War technology and weaponry to keep Brotherhood forces going indefinitely. But there was something else as well: Liberty Prime—a technological marvel that, if restored, could help the Brotherhood rebuild their strength and reputation, which had both been steadily declining for years.

The discovery was significant enough to earn Paladin Owyn Lyons a battlefield promotion to Elder, and a new directive from his superiors—to establish a new, permanent Brotherhood base in the Capital Wasteland and continue the search for any other advanced technology hidden in the capital's ruins.

Lyons accepted his new post gladly and founded the Citadel, built into and beneath the ruins of the Pentagon. It was a fortress the Brotherhood of Steel desperately needed and one they rushed to fortify.

Exterior
The Citadel is a large fortress with walls of stone and steel. It retains the shape which gave it its name, the "Pentagon." It only has a single entrance: a large metal gate usually guarded by multiple paladins and one sentry bot. (After the water purifier is completed and operational, these guards no longer appear.) A small corridor leads from the main gate to a door which provides access to the inner bailey.

The inside is inaccessible until the quest The Waters of Life is completed. Entry is scripted as part of the completion of this quest. Before then, the guard commander Paladin Bael will gruffly deny entry.

Bailey


The fairly large bailey serves as a training and sparring area. Under the command of Paladin Gunny, new recruits practice various skills from unarmed combat to firearm usage. To this end, the bailey contains shooting ranges and other installations for combat practice. A large hatch in the middle of the courtyard connects to the laboratory, although it cannot be used as an entrance by the player character. The laboratory and A ring, sections of the buildings which surround the yard, can be accessed through doors opposite and next to the main entrance. There are several beds here for the player character and initiates to use.

Citadel – A Ring
The A Ring is a small sector within the Citadel, which can be accessed directly from the bailey. The entrance is on the right upon entering the Citadel.

The A Ring contains the Lyons' Den, the Great Hall, the Library and entrances to B Ring as well as the Citadel laboratory. The Lyons' Den is the quarters of Lyons' Pride while the Great Hall serves as a briefing room for high-ranking Brotherhood members and the Pride. This is where the Pride gathers and waits for new action orders.

In the library, the Lone Wanderer can find the Vault-Tec terminal they need to consult as part of Picking Up the Trail. Another terminal reveals some background information on the Maxson family and various tidbits of information about the history of the Brotherhood. Another terminal contains information on a UFO that crashed shortly before the war and a plan to send mutant rodents to weaken China.

Citadel – B Ring
The B Ring is another section within the Citadel which can only be reached from the A Ring via two doors in the back. It consists mostly of sleeping quarters for all Brotherhood of Steel members as well as a medical bay and the private quarters of Owyn Lyons and Arthur Maxson. Lyons' unique laser pistol is in his safe in his private quarters.

Squire Maxson's room contains a hackable terminal in which, among various children's stories and other personal entries, one can find reference to a Guns and Bullets magazine under the bed in the Lyons' Den (A Ring).

The medical bay is home to Sawbones, a unique Mister Gutsy robot who is doctor of the Citadel, which Knight Artemis finds "creepy."

Citadel – Laboratory
The laboratory is the third sector of the Citadel, connected to both the bailey and the A Ring. It spans two levels and consists of the main working area, the armory and sleeping quarters for the scribes. Various terminals with technical background information on weaponry are scattered all over the place.

The lab is naturally the working place for most of the scribes, save those of the Order of the Quill. While they are conducting research on various fields such as threat assessment, weaponry and defensive technologies, their main focus is the work on Liberty Prime, a gargantuan pre-War robot which was the main reason the Citadel base was established.

Scribe Rothchild, who is part of various main quests, is usually to be found in the area just in front of the robot, on the bottom level. In the vicinity of the robot dock, there's also a terminal with progress information on the work on Liberty Prime which allows one to run a sound check.

On the wall at the bottom level, there is a digital map display from which the Lone Wanderer can extrapolate the location of the Vault-Tec vaults in the Capital Wasteland if they have not already found them. After Scribe Rothchild has used it to show the location of Vault 87, the map markers will automatically be added to the Lone Wanderer's Pip-Boy 3000.

There is a graphical error in the location of Vault 108 between the Pip-boy 3000 and the vault map on the wall. The wall map shows it north of Canterbury Commons and the Pipboy shows it south of Canterbury Commons.

The armory is located in an extra room on the bottom level and is run by Knight Captain Durga. She will trade with the Lone Wanderer if they have Elder Lyons' permission, which is easily obtained.

Inside the laboratory on the same floor entered from, there is a room to the east. The companion Star Paladin Cross is located in that room, along with a set of power armor in poor condition.

Citadel armory
If the Lone Wanderer chooses to destroy the Citadel in Who Dares Wins, they will find a door leading to the armory within the crater and one on the far side of the circular path around the crater. This section is not to be confused with the regular armory located in the laboratory.

Within this armory, there is a terminal describing several "incident reports" and a wall safe (unlockable through the terminal) containing Callahan's Magnum.

Inhabitants

 * ¹ After the quest Death From Above

Appearances
The Citadel appears in Fallout 3 and is mentioned in Fallout 4. The pentagon is referenced in Fallout 76.

Behind the scenes
"The Citadel" was the original name of the Cathedral of Fallout in early design documents (like the Vault 13: A GURPS Post-Nuclear Adventure timeline), as it was also the name of a similar structure in Wasteland.

Bugs

 * There are at least two Brotherhood of Steel initiates using the firing range, and one is firing a laser rifle. Nobody will become hostile if you shoot the laser rifle out of his hands, and he will start throwing frag grenades at the target. Many of his throws will either be off target or ricochet in various directions, causing numerous casualties among the nearby Brotherhood of Steel. When attempting this by using V.A.T.S., it is possible that if targeting the "weapon" too many times, the initiate will take out a grenade almost instantaneously after the rifle is shot. If this happens, you may accidentally shoot the grenade and kill the initiate and anybody close.
 * The radio in the bailey will continue to play GNR as if Three Dog is still alive after the player has killed him.
 * It is possible to gain access to the Citadel as early as level 2 through a nearby hole north of the Citadel, atop a pile of rubble. The player can then speak to Paladin Gunny and receive Power Armor Training.
 * Utilizing this same method to access the Citadel, and then reading the Vault-Tec Terminal's entry on Vault 87 will prematurely trigger Picking Up the Trail, bypassing most of the questline and allowing players to potentially finish the main quest without even entering Vault 112, as well as cancelling out most of the Enclave's invasion of the Capital Wasteland (Enclave encampments do not appear unless The Waters of Life is finished, though troops still appear at Vault 87, Raven Rock, etc.). Characters will also speak as though James was dead, even if the relevant stage of The Waters of Life hasn't been reached, and Madison Li and her colleagues will speak as though they were already at the Citadel, even if they haven't departed from Rivet City. Also, the option to fast-travel to the Jefferson Memorial will still be available, as this also only becomes disabled by completing The Waters of Life.
 * However, the above glitch will have to be utilized again to complete The American Dream, as the Citadel's entrance will still be sealed shut, though it will open for Lyons' Pride during Take it Back!. This may also lead to complications with The Waters of Life and Trouble on the Homefront depending on when the glitch is executed.


 * It is possible for Angela Staley to spawn outside the Citadel upon fast traveling. She is capable of all her dialogue options as if she was in Rivet City. She immediately begins walking back to Rivet City, but can be spoken to.
 * At the firing range, the Brotherhood of Steel initiate using a laser rifle will shoot through the wall every time he shoots.
 * If, when the Citadel gate first opens, you walk against the door until you can get through, then open the door before the gate finishes opening, you cannot gain bad karma and can take anything without anybody considering it stealing and you won't get attacked by anyone for any reason. This glitch never goes away and the game and story can continue as normal.