The city of Boston on Monday offered tours of an abandoned subway tunnel located underneath City Hall Plaza, and we sent photographer Jesse Costa along.

The tunnel connected two stations that no longer exist: Scollay Square (now Government Center) and Adams Square. It was closed off in 1963.

The city hopes to offer more tours of the tunnel in the future.

City archaeologist Joe Bagley stands before a door in the City Hall garage, the gateway to the old MBTA tunnel. (Jesse Costa/WBUR)

Bagley ducks through a small doorway into the rear section of the tunnel. (Jesse Costa/WBUR)

Marc Voltus shines his flashlight into an opening in the side of the tunnel. (Jesse Costa/WBUR)

The second of two sections of the old MBTA tunnel (Jesse Costa/WBUR)

The original rusted-out supports are features of the tunnel highlighted by city archaeologists. (Jesse Costa/WBUR)

Some signage from the old Adams Square station still hangs on the wall. (Jesse Costa/WBUR)