The headquarters of the affluent Garrahan Mining Company not only emphasize the splendor of the Garrahans, but also the mining history of Appalachia, burrowing deep underground beneath the exclusive township of Bramwell. Unlike the Hornwrights, who opted to erect the seat of their corporate power in downtown Charleston, the Garrahans stayed on the southern edge of Mount Blair, with the company headquarters stretching in the shadow of their Mega Mansion.
The lobby of the headquarters is sunken beneath the surface of the ground, with glass panels letting in sunlight to illuminate the interior. The main lobby is below ground, accessible either through the doors in the atrium, which deposits the player right in the lobby, through the monorail tunnel, which delivers the player down the tunnel to the station inside the headquarters, and finally through the parking lot, which leads to the break room and security checkpoint in the research wing.
The lobby has several points of interest. On the ground floor, on the western face, is the cafeteria and the conference room. Just up the stairs is the admin department, with a locked safe (level 3) controlled by a terminal (level 2) and the Garrahan estate access key on the desk. Directly opposite the entrance to the lobby is the CEO Vivian Garrahan's office, with the somber musings on the challenge she issued to Hornwright and the dire straits the company ended up in when they failed. The office also contains a bobblehead spawn point and a steamer trunk.
On the eastern face, by the CEO's office, is the control room for Garrahan activities. Right next to it is the corridor which leads to the development laboratories, where the Excavator power armor was created. The fabrication and testing room to the east contains two power armor stations, three spawns for Excavator armor components, with a magazine spawn point to cap it all off. There is also a weapons, armor, and chemistry workbench inside.
The testing, control, and assessment lab to the west contains a tinker's workbench and a power armor frame spawn point. Just next to it is the control room where the power armor was registered and a small excavated cavern where it underwent iterative development. The northern end of the corridor leads to the mezzanine and break room, which then goes to the parking lot beyond.
- Plan: Chemistry workbench - Inside the R&D lab, on a desk with an auto-miner, to the right of a chemistry workbench.
- Plan: Tinker's workbench - Inside the R&D lab, to the left of a tinker's workbench.
- Random Vault-Tec bobblehead - Inside the CEO's office, back shelves.
- Random magazine - Inside the middle of the R&D lab, between the power armor stations, on a counter.
- Random power armor mod plan - Inside the R&D lab, on a desk with a broken terminal in the southwestern corner.
- Garrahan Estate access keycard - On the CEO's desk. The key will allow access to the Garrahan Estate elevator on the second floor (one floor down from the lobby) at the U-shaped desk at the back of the room. A second one can be found in the side office in the nearby Admin area.
- Excavator power armor plans - In a project manager's terminal on the bottom floor while completing the side quest Miner Miracles
- Power armor chassis with T-series armor pieces in the R&D Department at a power armor station. Multiple power armor pieces can also spawn on the counters in the middle of the room.
- Fat Man - On the monorail line. Climb to the monorail platform outside the main building and then onto the station roof. Drop onto the monorail line and follow it away from the Headquarters. It will spawn just before a break in the line.
- Fusion core - In a fusion generator in the carpark, behind a Picklock 0 door.
- Charleston Herald - Man vs. Machine - Note, beside the terminal on the reception desk in front of the CEO's office.
- Charleston Herald - Hornwright wins! - Note, beside the terminal on the CEO's desk.
- Civic Center booth key - Under the CEO's desk.
- Harold Frost's R&D holotape - Holotape, on a desk by the tinker's workbench in the R&D section.
The Garrahan Mining Headquarters appears only in Fallout 76.