Central Park is NYC’s biggest green space and one of the prettiest city parks in the world. It offers up 843 acres of meadows, fields, tree lined paths, a lake, resevoir, outdoor theatre, and castle. Highlights include the famous Strawberry Fields, Sheep Meadow (a 15 acre field), Loeb Boathouse and its waterside eatery, Bethesda Fountain near the lake, and the Shakespeare Garden (bewteen 79th and 80th streets). With additional time or inclination you can rent a row boat from the Loeb Boathouse or visit the Central Park Zoo. In the summer check out the free outdoor concerts held on the Great Lawn or Shakespeare in the Park productions held at the open-air Delacorte Theatre. The Central Park Conservancy offers guided tours of the park focusing on different aspects. Check out their website for specifics. If walking isn’t your thing, consider a Central Park Bike Tour instead.