Vault 3

Vault 3 is one of the undeground complex, the so-called Vaults constructed before the War. It was constructed in the southwestern part of Las Vegas, on the outskirts of the city's industrial sector. Save for some flooding in the lower levels, the Vault is still in working condition. It is occupied by the Marauders.
Due to the unlimited, invisible, mental attacks at the entrance, Vault 3 is very dangerous to explore for anyone until a defense is figured out. DR boost is NOT a defense.
 
==Layout==
The Vault is located under a building in the South Vegas ruins and is the base of operations for a Marauders force. 
The surface area is walled up, and patroled by Marauder Suiciders and Grunts. The two gates on the wall are besieged by Military men, with eastern gate is harder than western gate. 
The Vault door, which is opened by the adjacent control panel, is connected directly to the South Vegas ruins and therefore provides no loading point for the Vault interior. This explains the lack of a door opening sequence.
Inside the entrance is a Marauders guard team, with random chance of an Iron Priest spawned near the entrance area. Worst of all, there's unlimited invisible mental attack that DR boost only provide a minimal defense (even at 90)
The walls of the Vault are covered with graffiti, presumably done by the occupying force. Much of the graffiti in the Vault is the same as that which can be found on the bunkers in Hidden Valley. In one of the toilets, there is graffiti on the wall of a stick man and woman. It's an enlarged version of the one in Hidden Valley. Overall, there are about five hackable terminals inside the Vault, which contain information about the Vault's history.
Vault 3 consists of three areas:
===Recreation area===
Vault 3 seems to have a much larger recreational area than the other Vaults. The recreation area also includes several pool tables and some minor loot. There is a locked door containing multiple Coca-Cola bottles, and one Nuka-Cola Fascism. Within the recreation area, there is a locked door leading to the maintenance wing.
===Maintenance wing===
The throne room in the northern part of the maintenance wing 
===Living quarters===
On the main floor of the living quarters, there is a cage 
Two of the rooms in the living quarters each have a deceased Fiend on a bed, surrounded by empty syringes, Jet and Psycho. Around the southern part of the living quarters is a bedroom containing a terminal with an administrator "Billy boy" and a function called "Compose Automated Blast Message." However, this does nothing, stating that the system is offline. Some of the Vault is flooded, and the flooded areas are long and difficult to swim through with enough time to return for air before taking drowning damage. In addition, the water is irradiated at 1 rad/sec. The rebreather or Turbo will aid in searching these areas. 
===Recreation area=== 
* Behind a Very Easy locked door (northwestmost room) connected to the main part of the recreation area is a room with a Nuka-Cola Quartz, Nuka-Cola Victory, and 20-30 pool cues.
* Several bobby pins in front of every locked door, lying on the floor. They are barely noticeable due to their size and low visibility.
* 90 empty Nuka-Cola bottles and 17 milk bottles spread throughout the area.
===Living quarters=== 
* A Chinese Army: Special Ops Training Manual on the bookshelf, in the large bedroom behind a door secured with an Average locked terminal, immediately opposite the entrance to the living quarters from the recreation area. The book is on a shelf immediately to the right upon entering.
* Sunset Sarsaparilla star bottle cap on a desk in a room next to a bottle of Sunset Sarsaparilla in a southern room of the living quarters, one floor above the flooded area. It's in the room across the hall from the room with a terminal that says "Hello Billy boy!" when accessed.
* A pair of binoculars are on the bookshelf outside the overseer's office. Another pair are on the shelf next to the observation window in the overseer's office.
* There's a 25% chance of finding a Vault 3 utility jumpsuit in the 25 lockers spread throughout the living quarters and maintenance wing.
===Maintenance wing=== 
==Notes==
* If the Courier stands outside the Vault door with Veronica as a companion, it triggers a point for her companion quest.
* If the Courier enters the cafeteria area of this Vault with Lily Bowen, she will comment about herself when she was a small girl and will reminisce about her first kiss.