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The Mechanist's lair, formerly the United States of America Robotics Technology Facility RB-2851,[1][2] is a location and settlement in The Commonwealth in 2287 that appears in the Fallout 4 add-on Automatron.


The Mechanist's lair was hidden underneath the RobCo Sales & Service Center which primarily sold and maintained terminals. Employees of the service center were told specifically not to interact with any abnormal crates, or else they would be "taken to see our friends below." In a storage room for the center, a large door which requires an M-SAT to enter leads into a large underground pre-War facility that was used for the development & construction of Robobrains (jointly run with General Atomics and the United States Army Robotics Division). Part of it functioned as a pseudo-prison which housed prisoners, who were later operated upon to remove their brains. After wiping their brain of memories and passing assorted tests, the brains would then be housed in a Robobrain head and mounted to any of a number of devices, including the bodies of a normal Robobrain, controlling stretchers or even controlling operations inside the control center.

Sometime before the events of Automatron, Isabel Cruz discovered the facility while scavenging and took it upon herself to use it to create an army of robots to save the Commonwealth from anything which may hazard humans.


The lair is located on the map slightly north of the East Boston Preparatory School. It is behind an unmarked building, and near a warehouse by a bridge and a small wharf. A freight elevator inside the building (enter the door named "garage") will take the Sole Survivor directly to the underground location. Upon completion of the add-on, the location becomes a new settlement.

Settlement information

  • Despite being another interior settlement, this has significantly more customization options than Home Plate but will have a settlement building limit, unlike Home Plate.
  • The Mechanist's lair functions like an exterior settlement, in that settlers can be moved here, and supply lines can be established.
  • The following settlement crafting options are unavailable:
  • There are some patches of 'earth' on the top level in the northernmost corner, just outside the entrance to the facilities wing, where water pumps can be placed. Some can be placed on the workshop's level.
  • The crafting stations spread across the complex outside the construction area are linked to your workshop as if they are part of the settlement.
  • The upper levels of the settlement area are at the correct height to structure objects.


Notable loot

  • Eyebot model - On top of some filing cabinets in the locked room with a skeleton hanging out the window, across from the generator.
  • Facilities director's holotape - Next to a locked (Novice) ammo box by the facilities management terminal.
  • Forfeiture terminal password - Located behind a desk as you enter the research wing, below the watch station terminal, gives access to the property storage lockup terminal.
  • RobCo Sales and Service Center key - Directly to the left on a file cabinet when entering the lair. Opens a door and a safe.
  • A Mr. Handy model and the lead engineer's holotape are located on a desk next to the chief engineer's terminal in the quality control area.
  • A fusion core - Found in a generator after entering the Mechanist's lair. Lefthand side before the laser grid.
  • Perfectly preserved pie - Inside an Eat-o-tronic in the room with the button-operated platform and garage door.
  • A Vault-Tec lunchbox - By a skeleton at the end of the robot storage area (underneath a yellow eye protection poster). Another is located behind the generators at power substation B on a red stepladder.
  • Day Tripper - One floor above the desk which contains the Mr. Handy model. It's on the left desk which has a dead researcher in front of it.
  • Four Nuka-Cola Quantums.
    • One can be found in a crate after the fourth gate.
    • Two can be found in a crate on the raised left side when the ramp goes down, by Jangles the Moon Monkey and a cymbal monkey playing video games.
    • Another can be found in the room with the assembly lines.
  • Several robot parts models are scattered around throughout the interior.
    • In a locker just after the power substation A where the floor becomes flooded.
    • A second model is located on a shelf behind a Master-locked terminal in the research wing.
    • A third model is in the brain extraction area of the research labs near a terminal.
  • Mr. Gutsy model - Behind the watch station terminal desk just after entering the research wing.


  • Protectron model - Found in a surgical tray by a terminal in the cell observation area located above the cells.
  • Stealth Boy - Located at the end of the cell observation area on a box to the right of a hole in the floor.

Brain extraction area

Mechanist's headquarters


  • The player character can confront the Mechanist directly by loading the lead engineer's, facilities director's and chief scientist's holotapes into the terminal in the room directly next to the decontamination/laser tripwire hallway near the lair's entrance, lifting the security lockdown and enabling the use of the elevator.
Alternatively, the player can listen to the holotapes from the Pip Boy when near the terminal. Upon, closing the Pip Boy while the tape is playing, an automated voice will acknowledge the speaker's voice. Once all three tapes are played, the automated voice will indicate that the player needs to confirm the manual override by using the terminal.
  • The area with the overhead conveyor lines spawns robots on the spot, each with a chance of being a legendary robot generating a new legendary loot result each time the game is loaded here. However, only a limited number of robots from each line can be knocked down before they stop production.
  • Outside of the Mechanist's bedroom is a small button on a coffee machine that opens up a hidden door at the end of the hallway. The room contains a terminal, missile launcher, missiles, locked safe, and a few packets of Mentats in a drawer. It is possible to lock oneself in this room.
  • This is one of the few interior locations which can be fast traveled to and from.
  • The exterior door cannot be opened until the quest Restoring Order is active.
  • After entering the facilities wings, continue until reaching the descending grated ramp. On the left, jump onto the ledge and over the pipe, one will find a Jangles the Moon Monkey and a cymbals monkey appearing to play pong while drinking two Nuka-Cola Quantums.
  • The doors in the lair open in a similar pattern to the ones by the original Mechanist in his lair at the robot repair center from Fallout 3.


The Mechanist's lair appears only in the Fallout 4 add-on Automatron.


  • Icon pc.png Icon ps4.png Icon xboxone.png After completing the final quest, leaving the building may cause the game to crash. [verified]
    • Fast traveling directly to another location, rather than leaving through one of the doors, may solve the issue.
  • Icon pc.png There is a chance for a saved game that the Mechanist's lair cell may become graphically glitched when facing certain directions. Textures may pop in and disappear as you angle the camera and FPS drops dramatically when looking in that direction. There is no known fix for this issue so far. The only way to circumvent this bug. [verified]
  • Icon ps4.png Location and power armor locations can appear in the incorrect location on the map when inside the Mechanist's lair. This is corrected upon leaving the building. [verified]



  1. Sign at the entrance and below the Mechanist's logo in the settlement area
  2. RobCo Sales & Service Center terminal entries