B, C at 86th St.; 4, 5, 6 at 86th St.
As organic to Central Park as the sprawling grassy lawn seems, when the park was built this area was actually a reservoir, which was finally filled in during the early 1930s. Today, the green expanse attracts city denizens with a number of free cultural events, including past summer performances by the New York Philharmonic and the Metropolitan Opera. It's also the perfect place to play: Softball, volleyball and soccer are just a handful of the sports regularly practiced here. During the summer, the lawn can look like a beach with thousands of barely-clothed sunbathers stretched out on towels.