Vault-Tec Headquarters

The Vault-Tec Headquarters building is located in the Vernon Square area of the Washington, DC ruins.

Building History
This was Vault-Tec's base of operations around the DC area. From this location (specifically, from the Vault-Tec Mainframe), you can learn where Vaults 87, 92, 106, and 108 are. This is helpful in the Optional portion of the quest Agatha's Song.

Enemies
The only resistance inside the building are the leftover security robots and a few turrets. The models inside are regular Protectrons, Sentry Bots, Robobrains and Mister Gutsies. Also, there is one special model of the Robobrain on the level where the Mainframe is. It is called the Masterbrain and is hostile towards you. You can turn off the Masterbrain, and all other security bots in the Headquarters, if you use the correct command on three employee terminals in the Mainframe area. Alternatively, you can destroy Masterbrain and use it to shut off all other security bots.

Super Mutants have also been found fighting the robots in the Guest Relations area. It seems they have been using the Vault-Tec HQ as a massing point, as Gore Bags, which are a common find within Super Mutant bases, are located in the Guest Relations men's restrooms.

Guest Relations

 * A Tales of a Junktown Jerky Vendor book on a table up the broken stairs on the right side of the room, in the cafeteria area. It is meant to only be accessible when you go down from Administrations again. However, with some with tricky jumping it can also be reached if you jump from the highest point of the broken staircase.
 * (Xbox360 - also confirmed on PC) as above, even if the player doesnt make the jump it is possible to land on a small ledge practically on the mezzanine. as you cant jump from here walk to the right and open the door to the administration block to be loaded into that portion of the building. walking back through the door will load you onto the mazzanine proper.

Corporate Offices

 * 1 Nuka-Cola Quantum It is located in the most Northwestern room on the second floor. It is on the bottom shelf of a bookcase. There's a door covering a hole in the floor in this room.
 * Big Book of Science in the room east of the room containing the Nuka-Cola Quantum on the second floor. The room with the book should have almost no floor. When you stand in the doorway and look straight through at the opposite wall, you will see two bookshelves slightly off to the right on the eastern wall. The Big Book of Science is on the top one. The easiest way to obtain it is to shoot it down.
 * Stealth Boy; northwest corner, top floor, in a storage closet just above the room with a random loot safe that also sometimes contains a Stealth Boy. (You have to walk around the edge of the missing floor to get to the closet.)
 * A Pre-War Book on top of a garbage can next to aforementioned safe.
 * Possibly a Power Fist opposite the shelf that the big book of science is on, on top of big wooden shelving in a footlocker.
 * In the second floor ladies' room near the exit to Administration, there should also be a Scoped .44 Magnum (with ammo) hidden in the cistern of the second toilet from the end, on the left hand side of the bathroom.

Administration

 * An issue of Grognak the Barbarian on a curved desk in a private office. The room is at the very west of the area.

Bugs
This editor found navigating Vault-Tec HQ particularly difficult with Dogmeat and Charon as followers on Xbox 360 with the 1.1 Patch. Upon reaching the second floor, both followers would run off in separate directions to attack unseen threats, usually resulting in Dogmeat meeting his demise rather quickly at the hands of a Sentry Bot or Mister Gutsy. For this reason, players might want to have Dogmeat wait before advancing past Guest Relations.

Masterbrain might not shut down in addition to the mainframe door not opening.

Easy Access to Top Level
It is possible to jump from the broken stairs of the Guest Relations Room to bypass the entire second floor. Just position yourself (preferably in third person) on the highest point of the stairs, and you should be able to do it in a few tries. Then, simply take the door to your right and go up the stairs. However, be aware that you will end up right near Masterbrain, so if you were intending to use the terminals to shut him down you may have a more difficult time.

Another possible method to get up the broken stairs is to wait for the Protectron to pass overhead, then as it is directly in front of you, target it with a melee weapon in V.A.T.S mode and then attack, and the player should be warped next to the Protectron. This may take a few tries but I can confirm it works (PC, 360 and PS3).

Activating the Vault-Tec Mainframe
Some people have reported that getting to open the doors to the Vault-Tec Mainframe does not work for them, i.e. selecting the proper command on all of the three terminals still does nothing to the doors, they remain shut. . (This may be due to deactivating the Masterbrain's uplink before entering the Mainframe or if you have already gotten the Vault locations from the Citadel- not confirmed [confirmation for Xbox 360: confirmation on PS3: Doors did not open even with no interaction with Masterbrain]) There is an alternative way to reach the Mainframe...

The player can activate the the Mainframe terminal from below, by jumping from the corner pipes to the right as you enter the room. From the pipes, jump on to any of the the big computers, and walk up as close to the Mainframe as possible. The option to interact with it should appear.

Master Brain
Destroying Master Brain prior to accessing the three employee terminals and examining Masterbrain and choosing to turn off all others can have the result of the Xbox 360 to hang.

Exploit Bug: After turning off the Masterbrain, a lot of the robots throughout the building (even the dead ones) will regain 1 hp and you can kill and loot them anew. Even if their "prime components" are missing, such as a leg or a head. Additionally, this is true even for bots reduced to ash/goo, attack them to gain more loot and XP as well.

Note that the Master Brain might have no visible brain.

Sometimes the defenses don't turn off after being deactivated (Xbox 360, PC)

Behind the scenes

 * Over the front desk right when you enter the building, suspended from the ceiling is Vault 101's door, as an example of Vault-Tec's technology.


 * On the Administration level there is an employee computer in which you can order Vault-Tec accessories. Upon selection of an item, the terminal will say that the item's cost has been deducted from the employee's salary. It is unlikely that you can acquire those items. When you select "Vault-Tec Bobblehead", it outputs: "Only Available to Executive Level Employee." While this may lead you to believe there is a Bobblehead located in the building, there is not. (Edit: Actually, this is a reference to the Xbox360 (and PC?) achievement/ PS3 Trophy for collecting all 20 bobbleheads: Vault-Tec C.E.O.)

Related Quests

 * Agatha's Song

YouTube Videos
Locating Vault-Tec Headquarters lzpGSXalvNE