Next to the building you'll see Chambers Street Station (trains J, Z) and just across the street you have Brooklyn Bridge-City Hall Station (trains 4,5,6), and City Hall Station on the other side of the park (trains R, W).
Trains 4, 5, 6, N, R, W, A, C, E, 1, 2, 3
Just get a subway map. You can easily find one on www.mta.info they mark it as Brooklyn Bridge City Hall. You will still need a map to get everywhere else around the city.
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