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.
The entrance is unmarked but can be easily found when looking for a drainpipe, found a short distance from the train wreckage due southeast towards the Lexington map marker. Start at the train carriage that sits on its side in the middle of the road and head directly southeast. 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 the 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 though 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.
Exploring the Switchboard's tunnels, one will encounter many deceased Railroad characters:
- 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 #1 - In the central area flanked by two sets of staircases. Go up the stairs, it'll be on the right side of the desk. The room it's in 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.
- If one selects "system diagnostics" on the turret section of the elevator control terminal, it says that the turret it is connected to is both online and is 53169116662270134434550000000000000000.00 meters away.
- One of the terminals in this area lists DEFCON reports, and suggests that it may have been the Chinese that were the first to strike during the Great War (terminal specifically states "poss." as in "possibly"). The last entry shows that the system went offline at 09:47 hours, the same time shown on most of the clocks in the Commonwealth and the Capital Wasteland.
- In the databanks room is a poster which shows mixed and matched robots. These are early prototype designs of P.A.M.
The Switchboard appears only in Fallout 4.
- Xbox One 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. [verified]
- Saving and reloading will fix this.