The Mechanist's Lair

The Mechanist's lair, formerly Robotics Technology Facility RB-2851, is a location and settlement that appears in the Fallout 4 add-on Automatron.

Background
The Mechanist's lair was hidden underneath a RobCo sales and 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.

Layout
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 Mechanists 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:
 * Food
 * Scavenging station
 * Garden plot
 * Recruitment radio beacon
 * Trading post
 * 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.
 * 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, making for easy development.

Inhabitants

 * The Mechanist
 * Sparks

Cells

 * 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

 * Chief scientist's holotape - In the brain extraction area of the research labs near the cerebral reconditioning terminal, on a shelf under the table next to a robot parts model.
 * Medical terminal password - Can be found on a Quantum robobrain guarding the facilities management room.

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

Behind the scenes
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. Although, unlike Fallout 3, the doors cannot be closed.

Bugs

 * After completing the final quest, leaving the building may cause the game to crash.
 * Fast traveling directly to another location, rather than leaving through one of the doors, may solve the issue.
 * 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 unfortunately no known fix for this issue so far. The only way to circumvent this is by starting a New Game and hope for the best. Note that this issue does not make it impossible to finish the quest but makes it really tedious. (Tested on version: 1.5.157, Automatron and Far Harbor installed)
 * 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.