The High Line is an elevated linear park built on a former freight railway line, running 2.3 km along the western edge of Manhattan from the Meatpacking District in the south through Chelsea to Hudson Yards in the north. It opened in 2009 and has become one of the most influential pieces of public urban design built anywhere in the past 25 years — widely imitated, never quite duplicated.
The park itself is excellent: beautifully planted with wild species that echo the vegetation that took over the old tracks, with good art installations, dramatic views of the city and the Hudson River, and a design that makes the most of the long, narrow elevated space. Weekends in summer are crowded; go on a weekday morning or in winter. The southern end in the Meatpacking District has the best food options nearby; the northern end at Hudson Yards has the least charm.