THE Statue of Liberty, Brooklyn Bridge and Times Square are all icons of New York. And since 2009, New Yorkers have added another to the list - the High Line, a public park built on a historic freight rail line elevated above the streets on Manhattan's West Side.
About 3.7 million people visited the High Line in 2011, making it the most visited park per acre in the city.
American Lisa Switkin knows why the High Line has been so popular. Her office is just four blocks away from the High Line and she has been visiting the place since 2004, even before it was open to the public. The associate partner and managing director at landscape architecture firm James Corner Field Operations, is the lead designer of the team that transformed the High Line into what it is today.
"The High Line has multiple stories and layers to it," says Ms Switkin, who was in Singapore recently as jury member for the annual President's Design Awards. "People who are into history find it intriguing that an old freight rail has been retrofitted. Those into ecology like that the old rail has been converted into a park, while there are others who are proud that this is a project that was approached from the bottom up and there is social engagement and community activism involved."
She adds: "The High Line is a way to see the city in a different context. People are rediscovering their neighbourhoods. Some parts of it cut through the back of buildings, so you can see the inner workings of the city."
When it is completed, the High Line will be a 1.5 mile (2.4 km) long elevated park, running between Gansevoort and West 34th Street. The first section from Gansevoort Street to West 20th Street opened in 2009, and the second section, from West 20th Street to West 30th Street, opened two years later. Work is now ongoing on the third section, which Ms Switkin says is the most complex to do. "It is ironic that after having designed two sections, the last is the most difficult."
Unlike the first and second sections which run through existing neighbourhoods, the third section runs over the Hudson Yards, where a massive residential-commercial development is being planned.
"There is nothing there now - so when designing the third section, we need to imagine what is going to be there," says Ms Switkin, who has a bachelor's degree in urban planning from the University of Illinois, and a masters in landscape architecture from the University of Pennsylvania.
The first two sections are a sequence of varied environments within a cohesive and singular landscape. For example, at the Gansevoort Woodland, there is dense planting and a grove of grey birch and serviceberry trees.
Her two favourite spots on the High Line are "on the sundeck of the 14th Street, which is close to the Hudson River; and at the Falcone Flyover". The Falcone Flyover is between West 25th and 26th Streets, where a metal walkway rises eight feet above the High Line, carrying visitors into a canopy of sumac and magnolia trees.
"When I first stepped on the High Line, it was a magical moment. I wanted to bring the area to life, but not to over-design it," she says.
The community and visitors have taken to the High Line in their own ways. There are flea markets, movie screenings and yoga sessions. "There is a woman who at 7pm every night will do a cabaret show on her fire escape stairs, and people would gather to watch. This is something that I didn't plan for."
She does not rule out other cities adopting the High Line idea. "The same idea can be transported, and we have the data to show how successful such an idea is. This concept is relevant, even in Singapore," she says. "But with each city, there will be different constraints with different aesthetics."
The third section of the High Line is expected to open next year, but Ms Switkin says that does not spell the end of the project. "Landscaping gets better over time, the story is constantly evolving. We never meant for the park to be fully finished. We anticipate more paving and landscaping, and the park will change as the city changes."