The Interborough Rapid Transit opened on October 27, 1904, to the joy of New York subway riders. In 1940, the IRT became the 4/5/6 when it integrated with the city-owned New York Subway system.
The City Hall station on the IRT local track was lavished with fine architectural details: glass tiles and large chandeliers. But the Gustavino vaulted ceilings and skylights were lost on busy commuters, and the stop was one of the least-used in the system. The nearby Brooklyn Bridge stop was frequented by the express train and closer to connecting streetcars.
In 1945, the station was closed when the tracks had to be expanded because the curved track could not be lengthened. The 6 train used to make all passengers disembark from the train at the Brooklyn Bridge stop. But that's no longer the case. The skylights have been reopened and the station opened back up. Passengers can not get out of the train and experience the City Hall Station as they once might have, but they can stay on the train as it turns around on those tracks and heads back north.
The New York City Transit Museum hosts sporadic tours of the abandoned station; however, you must be a member of the museum to attend. Check the website for details.