NEW YORK — In the warrens of Manhattan, a meadow hovers above the asphalt outwash of warehouses and abandoned factories.
It flowers on a vacant viaduct with a seasonal canopy of Queen Anne's lace, purple aster, hyacinth, wild cherry, scallions, moss and iris -- seeded by vagrant birds and the wind.
They call it the High Line.
The derelict ribbon of elevated railway threads through the upper stories of Manhattan's far West Side for almost 1 1/2 miles.
The tracks, unused for nearly a quarter-century, disappear into warehouses and dodge between buildings in an architectural game of hide-and-seek.
While thousands of people scurry under its stained steel supports every day, unaware of what is overhead, the High Line has become nature's own urban renewal project.
Ambitious redevelopment plans also are blooming here.
Where generations of New Yorkers had only seen a rusting eyesore that blocked the light, two urban pioneers saw the potential for a park in a metropolis starved for open space. After all, local soccer leagues play matches on a rooftop and golfers practice fairway drives on a pier.
When freelance writer Joshua David and painter Robert Hammond first followed their curiosity over a barbed-wire fence onto the High Line five years ago, they found themselves on an elevated avenue of greenery that overlooked the art galleries of Chelsea and the designer boutiques of the Meatpacking District -- two of the city's newly fashionable neighborhoods.
To the west, there were shimmering vistas of the Hudson River; to the east, the Empire State Building towered.
The abandoned railway, the pair realized, could become a place where pedestrians could stroll unimpeded for 22 blocks, suspended nearly 30 feet in places above the hustle of the streets.
"It is a beautiful, dreamy, evocative landscape ... a unique urban ecosystem," David said. "Yet it was relatively invisible."
People can't easily reach the High Line from the street. The stairways have vanished and the entrances -- although hidden -- are protected by padlocks and railroad security.
David and Hammond were galvanized by the idea that an open space of such magnitude could exist in New York City and that no one could get to it.
The pair launched the Friends of the High Line preservation drive, which quickly became one of the city's most fashionable causes. Today, it has about 6,000 supporters and a $1-million annual budget. There is a staff of seven, a newsletter, a promotional video, a website and an ambitious outreach program. A yearly fundraiser, hosted by fashion designer Diane von Furstenberg and actor Edward Norton, has become a staple on New York's society pages.
"They have been very creative in generating a buzz and engaging people," said Frank Uffen, managing director of New Amsterdam Consultants, a firm involved in redeveloping a mile-long viaduct in downtown Rotterdam, the Netherlands.
Architects and designers now nurture visions of an urban wilderness on the High Line -- along with schemes for windmill farms, botanical gardens, an aerial tramway and, improbably, overhead cow pastures, all connected to the street by elevators and stairs.
One designer offered a plan for turning the rail line into an inner-city roller coaster. Another proposed creation of a High Line swimming pool, with lap lanes 1 1/2 miles long.
This month, David and Hammond are helping city planners evaluate seven design teams competing to oversee development of a master plan. The seven were picked in April from 52 groups of architects, urban planners and landscape designers.
David and Hammond estimate the price tag for renovation and landscaping will be $40 million to $60 million, to be paid with public and private funds.
Vintage viaducts are the newest enthusiasm of urban preservationists recycling America's past.
Community groups from Chicago to Philadelphia to the Florida Keys have mobilized to turn the abandoned rail lines into parks -- many inspired by the transformation of a crumbling 19th century Parisian viaduct into a 3-mile-long botanical garden.
The Promenade Plantee, which opened in 1998, is linked by elevators and stairways to the Avenue Daumesnil nearby. In the space beneath its 60 stone arches, Paris urban planners encouraged construction of art galleries, cafes and artisans' studios.
As much as anything, said transportation archeologist Thomas Flagg, the reclamation projects have arisen from a change of heart toward abandoned industrial structures.
Nostalgia for a vanishing manufacturing economy joins with post-modern artistic sensibilities and, driven by real estate speculation, blight becomes beauty.
"All the space is getting filled in," said Ben Helphand, who recently helped organize Friends of the Bloomingdale Trail to reclaim 37 rail bridges along Chicago's North Side. "What do you have left but these unused industrial areas?
"You see them in a new light. The reinvention of these is happening all over the place."