Central Park, New York
New York City's Central Park is the most famous urban greenspace in the United States, and perhaps even the world. It's sheer popularity might make it a turnoff for tourists in search of some peace and quiet: 35 million people visit it each year. However, with more than 800 acres, there are plenty of sections where visitors won't be elbow-to-elbow with other tourists.
A walkable woodland area called the Ramble is a haven for bird-watchers, the other areas of the park provide a range of activities, from hiking, biking, skating (both on pavement and on ice in the winter), and paddleboat riding. Central Park is a cultural attraction as well as a place to enjoy the greenery. Concerts and performances are held regularly during the summertime, and art installations include dozens of sculptures and even a 2-acre area dedicated to John Lennon.