Climbing One57

Extell Development’s new luxury condo tower, One57, has already done some $1 billion in sales, and most of its überwealthy buyers have had to envision their new apartments from floor plans and renderings.

But a few lucky buyers — and their brokers — have had the chance to visit the building’s construction site, sampling the views from the top floors of the 1,000-foot-high glass tower, which will be the tallest residential skyscraper in Manhattan when it’s completed in 2013.

Most of the time, prospective buyers are not allowed on construction sites, said Elizabeth Sample, a Sotheby’s International Realty broker who has done deals in the building.

“Generally, you are not allowed to go up there with your client,” Sample said. “That could be for many reasons: it could be for liability in case anyone was hurt, or it could be that if they do it with one person, they have to do it with everybody else.”

But since One57 topped out in June, Extell’s Gary Barnett has made some exceptions to the no-visits rule, inviting a few billionaire buyers to ride up the construction elevators and take a sneak peek at the building’s fabled penthouse views. The luxury condo, built to stand on top of a 25-story Park Hyatt hotel, will boast apartments overlooking Central Park from as high as a 90th floor.

Nikki Field, a broker at Sotheby’s International Realty who has represented at least three buyers in the building, said she has visited the site several times.

“It’s an astounding view,” Field said of the experience. “The views go all the way around the Hudson up to the Palisades. You can see the New York Harbor, Brooklyn — you see Staten Island, it’s that high! Like being in a balloon.”

The views have had a similar effect on buyers, Field said: One of her clients said the view from One57 had twice the impact of the vista from his current apartment on a very high floor of the Time Warner Center. Another was so pleased by the exclusive invitation that he flew into New York just to visit the construction site.

“When you rise above the canyons of Manhattan and the view’s open — I haven’t been with anyone who didn’t gasp,” Field said.

Of course, Extell isn’t about to let everyone climb to the top of the tower. The buyers who got the invite had already signed contracts to purchase some of the building’s priciest units, brokers said. Barnett didn’t return calls for comment about his rationale, but Field guessed that the invites are an attempt by Extell “to build a relationship with buyers, courting them and hoping they will follow the developer in other parts of the world.”