I walk the Brooklyn Bridge, on average, once a week. It's my favorite thing to do in New York on a nice day. If you ride the 6 train to the Brooklyn Bridge stop, stay on. Look out the subway windows and you'll see the beautiful, abandoned City Hall subway station, built in 1906. Most subway stations today offer no architectural or historical value, but this one does.
There's something extremely eerie and ghost-like about seeing this station and thinking about how many people must have passed through it, starting in 1904. Though you won't see it like it is in the photo above, you will get a great glimpse.
I couldn't capture a good photo with the train moving so fast, but here is my best attempt.