New York, United States | Eighty years after it was shut off to the world, New York has reopened a secret woodland sanctuary a stone's throw from Fifth Avenue, just in time for summer.

The four-acre (1.6 hectare) Hallett Nature Sanctuary is one of three areas of woodland in Central Park, the huge expanse of nature in the Big Apple visited each year by an astonishing 43 million people.

The little sanctuary is hidden away at the southeastern end of the park, just meters from bustling designer boutiques and luxury high-rise apartment blocks. For decades it was fenced off and allowed to overrun.

"It was closed by the park commissioner Robert Moses in the '30s and Robert Moses thought it would become a bird sanctuary," said Doug Blonsky, president and CEO of the Central Park Conservancy, a non-profit organization that raises 75 percent of the park's annual budget.

"Unfortunately what happens, particularly in a urban environment, if you leave an area closed for a long time, invasive species or plant material take over, forcing out the natives," he said.

In 2001, the Central Park Conservancy decided to restore the sanctuary, which at the time had been completely taken over by wisteria strangling the woodland.

It took years to win the wisteria war. Schools and volunteers were enlisted. "A lot of people think wisteria is a beautiful plant with purple flowers. But if you let it go, it will take over an entire environment," Blonsky explained.

Rustic foot paths have been designed and covered in woodchips, and a pretty wooden gate has been installed at the entrance.

Wild local plants have been replanted and benches at the top of the promontory allow people to take in the view or listen to the birds while sitting hidden in the greenery, the skyscrapers south of the park poking out above the canopy.

- Much wilder -"It is quiet. It is much more wild. I like to think when you are coming here you are almost getting a glimpse of what maybe New York City looked like before it was developed in the 1600 and 1700s," said Blonsky.

Maintaining a wild landscape, is "very difficult," he told AFP.

"You want it to look like it is wild, but it is not. It is very manicured, every plant you see or almost see has been planted. We are constantly battling with invasive species," said Blonsky.

Some trees are dead, which, if elsewhere, would have been cut down and pulped into woodchips. But here they are being preserved for local habitat.

"Look what the woodpeckers have done," said Blonsky, pointing to a dead tree.

There are around 270 species of bird in Central Park. You can see many of them in the Hallett sanctuary, along with squirrels, racoons, ducks and birds pecking at puddles on the rocks.

There is even a woodchuck which Blonsky says "is very unusual."

For now, the sanctuary is open only three afternoons a week from 2pm to 5pm. In July and August it will also be open for two hours on Sunday.

But only 20 visitors will be allowed in at once to maintain the solitude and peace of the sanctuary. On sunny weekends as many as 200,000 people can flood into Central Park as a whole to relax or exercise.

The park's annual budget is $65 million, of which 25 percent is financed by City Hall and the rest raised by the Central Park Conservacy thanks to donations from park lovers and well-heeled residents living close by.