The bank is guarded by two raiders and one turret. Three routes are available to access the structure: an Advanced-locked door in the side alley to the north, a gap in the rubble near the wooden fencing to the southeast, and an unlocked door near the turret to the south. The building features a stairwell leading up to the third floor, and a roof accessed by an elevator on that floor. The side entrance in the alley leads to the stairwell, while the elevator inside the bank area leads directly to the third floor.
On the third floor near the stairwell is an Advanced-locked restroom with a first aid box. To the west are two elevators; the elevator on the left returns to the street-level entrance, while the elevator on the right ascends to an exit to the roof, where the MILA needs to be installed for the related quest. Farther to the west is the bank's vault area, with two terminals. The Novice-locked terminal grants control of a police Protectron. Behind a long counter in a small vestibule to the north is the Expert-locked terminal that unlocks the main bank vault. In the small office to the west opposite the Protectron is a Novice-locked safe. On the west wall north of the office is an exit to a walkway leading to an elevator to Congress Street garage.
- Weathervane: Commonwealth Bank: Tinker Tom asks the Sole Survivor to place atmospheric sensors on high vantage points to detect any anomalies in the air.
Commonwealth Bank appears only in Fallout 4.
As with many elevators in the game, sometimes, when one enters the elevator to the roof and presses the elevator button, the elevator will close but then run forever. [verified]
- This may be related to the positioning of the player character and/or their companion when starting the elevator. Having your companion get in first and move to the back of the elevator, then issuing the stay command, may prevent the bug from occurring. Jumping around inside the elevator may also cause it to become "unstuck."