Battery Park is a much smaller (25 acres) bit of green in Manhattan than Central Park. Located on the southern tip of the island, it was our afternoon destination after warming up and filling up. For a small park there was lots to see not all of which I'll write about or show photos of. (Google it. The history is fascinating.)
When we went to Charleston, SC in 2014, my one biggie was walking on the battery - just like those Southern Belles I'd read so much about.
Castle Clinton is now a National Monument. In the past, when it still had a roof, it was used as a theater and an exhibition hall and from 1896 to 1941 housed the New York City Aquarium.