The entrance is located directly south of Faneuil Hall, past a door with an Advanced lock on the south side. There is also an access point through a gap in the wall to the elevator. Both are guarded by two raiders and one turret. It is also possible to gain entry from the south side through a gap in the fence and an unlocked door. There are two accessible floors to this building and the roof.
The first floor is just a stairwell. At the top of the stairwell on the third floor is a locked (Advanced) restroom with a first aid box. The third floor contains two terminals. The Easy-locked one grants control of a police Protectron. Behind the counter, in a small vestibule, is the Expert-locked terminal that controls the main bank vault.
In the small office opposite the Protectron is a Novice-locked safe. There are two elevators. The one on the right goes up to the roof exit where the MILA needs to be installed. An exit door leads to a ruined walkway over the Financial District. It is possible to enter the building on the third floor via this walkway from the adjacent Haymarket Mall.
- Weathervane: Commonwealth Bank: Tinker Tom asks the Sole Survivor to placed atmospheric sensors on high vantage points to detect any anomalies in the air.
The Commonwealth Bank appears only in Fallout 4.