The station's configuration is unique, in that you enter from the sidewalk adjacent to City Hall Park directly onto the station platform, which makes this one of the widest platforms in the system. The northbound tracks are actually located in City Hall Park, while the southbound tracks are under the east side of Broadway. The fare control area is fenced off from the actual subway platforms. There is also an active tower at the north end, with a window that lets any waiting passengers observe Transit Authority goings-on. The platform tapers off towards the southern end, where the northbound and southbound platforms join.
The station's configuration, and the wide-open staircases to the sky above, is responsible for another distinguishing note: the number of birds that fly into and around the station.
This station was overhauled in the late 1970s, changing the station's structure and overall appearance. It replaced the original wall tiles, old signs, and incandescent lighting with more modern wall tiles, signs and fluorescent lights, as well as fixing staircases and platform edges.
The City Hall station is a bi-level station. It was initially intended that the local trains on the BMT were to terminate on the upper level, while the express trains using the lower level would continue on through lower manhattan and the Montague Street Tunnel. However, plans were changed before this could be brought into effect, and excess construction was terminated. As a result the lower level of the station which was to have been the express station is unused (except for non-rush hour storage of trains), as are the unused express tracks at Canal Street. Another effect of this change is that the southern end of the upper level station slopes downward. This is a result of platform lengthening, and as the initial plans called for the trains on the lower express platform to continue into lower Manhattan, the platform had to be adjusted.