This building in the city's western dugout is a single-floor structure. The main jail room contains one large Advanced-locked cell (occupied by Mel during The Big Dig) and a Nuka-Cola machine. To the east is a locker room, to the north is a restroom and a shower room, to the west is an old parking garage that has been converted into the barracks, and to the south is a small corner room with a desk.
Unless its alliance parameters are overridden by using the Protectron override program in the Expert-locked automated security terminal behind the cell, the Protectron in the nearby pod will attack all present if released, as the terminal suggests. If the holotape is used, the robot will instead patrol the security office.
Diamond City jail key - Inside a desk in the small room to the south. Must be stolen.
The security office only appears in Fallout 4.
Behind the scenes
The banners hanging on the wall in the main room match the years the real-life Boston Red Sox won the World Series (blue) and American League Pennant (red). The team's achievements after 1946 (relating to the 1967 season and beyond) are not displayed.