So many free things to do in Central Park that even if you tried you could not do all in a day or even a week.
Just take a nature walk to the “Imagine” tribute of John Lennon. Take photos of yourself there or with some other iconic figures throughout the park, including William Shakespeare, Balto, Alice & Wonderland and the oldest public monument in North America, The Obelisk.
If all your energy is not spent pass by the Belvedere Castle.