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 facility that pre-War 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 a building that is unmarked, and near a warehouse that is 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, it is a new player character home.

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
 * Brahmin feed trough
 * 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

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 from 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.
 * Using the cargo elevator immediately behind the original spawn point may cause robot companions to disappear, sometimes permanently.
 * 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 Mechanists lair. This is corrected upon leaving the building.
 * If you use a multiple companion mod you may run into the problem that a robot with an installed M-SAT (like Ada) won't open the Access Port doors in the Mechanist's Lair. This is because the door opening script calls the wrong companion to do the blue beam animation. Curie and Piper have been reported to open the doors even when the module was installed on Ada. If the other companion aren't near the access port it looks like nothing happens. This is especially confusing after the moving platform since you intuitively bring only your M-SAT robot with you while the rest are temporarily left behind. Bring all your active companions there before ordering the robot to use the Access Port.