The Switchboard

The Switchboard is an unmarked location in the Commonwealth in 2287.

Background
Before the Great War, the bunker was used as a secret base of operation for the Defense Intelligence Agency as can be seen written on the floor in the main hall. It was later discovered by the Railroad, who repurposed it as their headquarters. They also uncovered the Predictive Analytic Machine, a pre-War advanced robot designed to predict the future with extreme precision and accuracy, using the most complex formulas, methods, and algorithms based on the data provided.

It was not long before the Railroad's enemy, the Institute, discovered the location. Synths were later dispatched to wipe out the Railroad, forcing them to relocate to the crypts beneath Old North Church, leaving the bunker in the hands of the Institute.

Layout
The entrance is unmarked but can be easily found when looking for a drainpipe, found a short distance from the train wreckage located directly west of the Lexington map marker. Start at the train carriage that sits on its side in the middle of the road and look east, just below the road, for the drainpipe. The exit is an elevator in the basement of a Slocum's Joe, a pre-War doughnut shop west from Super Duper Mart.

Entry can be gained either by hacking a master locked terminal oneself at any time or by having Deacon do it during the Tradecraft quest. It is not necessary to be on the quest in order to obtain the perk magazine.

Clearing the location takes one on a journey through utility tunnels until a hole in the wall provides access to the bunker. All Railroad agents present are dead, but some of their defense systems still function and can be activated to help fight the synths that have invaded. After working through the opposition, one can restore power to the basement elevator to allow an exit through Slocum's Joe.

If Tradecraft is active, Slocum's Joe will be guarded by synths, turrets, and mines.

Railroad members
Exploring the Switchboard's tunnels, one will encounter many deceased Railroad characters:

Notable loot

 * Two fusion cores - One in the lower level generator room, near where the sewer entrance empties into the building, the other right near the end, behind a locked security gate, just before the elevator that leaves the area.
 * U.S. Covert Operations Manual issue #1 - In the central area flanked by two sets of staircases. Go up the stairs, it will be on the right side of the desk. The room overlooks a computer-filled work area.
 * Carrington's prototype - In the vault.
 * Two hazmat suits - Found on a table on the second floor, in the room where Carrington's prototype is located.
 * One mini nuke - On a shelf to the right of Carrington's prototype.
 * Two Stealth Boys - On a metal shelf with the prototype.
 * Deliverer - A silenced pistol obtained during the Tradecraft quest.

Appearances
The Switchboard appears only in Fallout 4.

Behind the scenes
The Switchboard is likely based on "The Notch", a Post-Attack Command and Control System Facility located under Bare Mountain in Hadley, Massachusetts, designed to survive a nuclear war and maintain communications links for the US Military. The interior is very similar, including the glass fronted balcony the player sees when they enter the facility.

Bugs
When using the terminal in the main hall underneath the office with the U.S. Covert Operations Manual, it is possible to get stuck in between the chair and the desk. Saving and reloading will fix this.