High Line Park in NYC. Open since 2009, it has fastly become another must see walk in the city.
Starting at Gansevoort St in the Meat Packing district and running to 30th Street with 8 access points, several with elevators, the sites are great on the old rail line as well as the views of the river, streets and buildings.
Traveling over three major neighborhoods, it's surely worth while to visit the streets as well. The Meat Packing District with its cobblestone streets is full of restaurants, shops and even an Apple store. Chelsea has over 100 truly diverse artist stores and galleries. To support the arts are a large residential area, dozens of restaurants, cafes and shops. Hells Kitchen and Railroad Yards are the final section.