Freedom Tower construction started

The Freedom Tower to be built at the site of the devastated World Trade Center in Lower Manhattan is still planned as the world’s tallest building, according to a revised model unveiled by the architects collaborating on its design.

The tower, to be a centerpiece of the rebuilding plan for the World Trade Center site, is to rise 1,776 feet -- a nod to the year the United States declared its independence. The height was originally proposed a year ago by architect Daniel Libeskind, since designated the site’s master planner.

In addition, a broadcast antenna attached to the tower is to bring the structure’s total height above 2,000 feet.

The tower’s angular shape and appearance has been altered as a result of Libeskind’s work with David Childs, the architect for real estate developer Larry Silverstein, the trade center leaseholder who aspires to replace all 10 million square feet of commercial space lost in the September 11, 2001, terrorist attacks.

Freedom Tower is to rise 70 floors and be topped by wind-harvesting turbines that designers predict will provide 20 percent of the building’s energy.

The tower’s height of 1,776 feet, symbolic for the year of American independence, includes a 276-foot spire.

The torqued tower -- its east and west sides twist as they rise -- and the spire are meant to echo the Statue of Liberty in New York Harbor.

The tower is to have a concrete core and be encased in a steel cable netting that will brace the building. Childs likened the cables to suspension bridge cables, such as those holding up the Brooklyn Bridge.

The building is to include 2.6 million square feet of commercial space, which would be on the market when the tower is completed in 2011.

Silverstein said he is not worried that no tenants are yet committed to move in.

“We have a hiatus of five years before the building is finished. It’s early to be talking about occupancy five years hence,” Silverstein said. “However, there are sufficient number of discussions with potential major space users, with significant needs in excess of a million square feet.”

Charles Gargano, the vice chairman of the Port Authority of New York and New Jersey, the transportation agency that built the original trade center and owns the 16-acre site, said the agency would occupy as much as a third of the building.

Gargano estimated the tower’s construction would cost $1.5 billion, or $1 million per 500 square feet.

Besides the public lobby, two concourse levels will house retail stores and provide pedestrian access to mass transit.

More than 60 floors will contain office space, capped by an indoor observation deck, a restaurant above that, and event space on top.