The Congress Street garage is located right across the street from Faneuil Hall.
The garage is completely wrecked. It is inhabited by raiders and has functional protectron pods with an access terminal nearby. The lower floors house two elevators, one of which takes the Sole Survivor to an unsafe ledge high in the wrecked scaffolding of the building, the other takes them to a walkway that leads to an alternate entrance to the Commonwealth Bank. This elevator also leads to some stairs that can allow the player character to access the highway.
Sometimes the raiders and protectrons will be dead before the arrival of the Sole Survivor.
Congress Street garage appears only in Fallout 4.
PC Playstation 4 If the player character attempts to open the hatch while the elevator is in operation, there is a chance the player character may fall through the ground to their death. [verified]