Vault-Tec Headquarters

Vault-Tec Headquarters is located in the Vernon Square area of the Washington, D.C. ruins.

Background
Vault-Tec's base of operations in the DC area is located east of the Vernon Square metro station. Accessing the mainframe requires authorization from all three system operation terminals. Station 3 is on the first floor of the administration room, with terminals 1 and 2 upstairs of the facility.

Inside the building, automated turrets, protectrons, sentry bots, robobrains, Mister Gutsies are found. One named model of the robobrain, the Masterbrain, is on the same floor as the mainframe. One can turn off the Masterbrain and all other security robots in the Vault-Tec headquarters by using the correct command on the three employee terminals in the mainframe area. Alternatively, one can destroy Masterbrain and use it to shut off all other security robots. Super mutants fight the robots in the guest relations area.

Guest Relations

 * A Tales of a Junktown Jerky Vendor skill book on a table in the cafeteria beyond the broken stairs, which can be accessed from the Guest Relations door in the northwest of the administration area. The book is on the right side of the room, in the cafeteria area.
 * Two boxes of Sugar Bombs, which can be used for the unmarked quest Sugar Bombing Run, are also located near the table with the Tales of a Junktown Jerky Vendor book, in the area beyond the broken staircase.
 * Two Vault-Tec lunchboxes in the same cafeteria.

Corporate Offices

 * One Nuka-Cola Quantum 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.
 * A Big Book of Science in the room directly east of, and connected to, the room containing the Nuka-Cola Quantum on the second floor. The room with the book should have almost no floor. The book is located on top of the higher bookshelf on the wall across from the entrance, if you approach it from the left crouching on the edge and look up, the book sticks out a little and you can just grab it.
 * A Stealth Boy on a shelf in the northwestern-most room on the second floor. The door to the room can be accessed by walking along the left edge of the missing floor, and also contains ammunition boxes.

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.
 * Seven Vault-Tec lunch boxes are located in a closet in the most northeast room.

Related quests

 * Agatha's Song: The Vault locations retrieved here help with the optional portion of the quest.
 * The Nuka-Cola Challenge: There is a Nuka-Cola Quantum and a Nuka-Cola vending machine with a chance of spawning a Nuka-Cola Quantum.

Appearances
The Vault-Tec Headquarters appears only in Fallout 3.

Bugs

 * It is entirely possible that once you've killed the Masterbrain, and attempted to shut down all other robots, that all other robots and turrets will remain active and hostile.
 * It is possible to get double XP by destroying all robots then by using Masterbrain to shut everything down, on your way back/out, all the robots killed will have 1 bar of HP. Shoot them again and you will get the XP again. Robots you have vaporized or melted with energy weapons will not be revived but their inventories will be broken.
 * It is extremely likely (if the player character has already finished Agatha's quest) that the door which leads to the mainframe can't be opened, even if one manages to get the right authorization from all three system operation terminals. The mainframe terminal can still be accessed by entering the first floor of the mainframe room and jumping on to the pipe coming out of the wall in the south east corner of the room. From there it is possible to jump onto the computer on the south wall. Then, looking up at the terminal overhead, jump and access the terminal while in the air. Alternatively, the door can be opened with the "" -command when selected in the console.
 * There is a shopping cart outside the building located in between the vending machine and the entrance which, when brought to a specific spot, will disappear and reappear several times, depending on where your character is facing.
 * If you jump on top of the filing cabinets in the southern part of the corporate office, next to an industrial vacuum cleaner, you will get stuck under the ceiling. These are the filing cabinets blocking the hallway, so you might attempt to climb over them.
 * If you place a marker down on Vault-Tec headquarters, it may lead into the opposite direction in some occasions.