One World Trade Center, designed by Skidmore, Owings and Merrill, has surpassed the height of the Empire State Building to become the tallest building in New York City, US.
The installation of two 26ft steel interior columns on the top of the skyscraper brings the height of the building to 1,271ft above street level.
The under-construction One World Trade Centre building will incorporate 104 floors when the building tops out in summer 2012, rising 1,368ft, 118ft above the height of the Empire State Building, which is 1,250ft above street level.
Upon completion, the building, also known as Freedom Tower, will be 1,776ft tall (including the building's antenna) and will house 2.6 million ft² of office space, a two-storey observation deck, skyline restaurant, retail spaces, broadcast and antenna masts and four levels of underground parking.
The building is being developed by the Port Authority of New York and New Jersey in consultation with structural engineer WSP Cantor Seinuk.
The building will have 1 million ft² of glass facade, the equivalent of about 20 football fields.
The planned green tower is anticipated to achieve LEED Gold certification and is also expected to house the World Trade Center transportation hub and 9/11 memorial.
One World Trade Center is already 55% leased and the building will serve as the headquarters of the publisher Conde Nast, which has leased more than 1.2 million ft² of floor space, spanning 25 floors.
An additional 190,000ft² has been leased by Vantone China Center and the federal General Services Administration is in final review of a lease for 300,000ft².
Construction on One World Trade Center is expected to be completed in late 2013 or early 2014.
Image: Upon completion, the building, also known as Freedom Tower, will be 1,776ft tall. Photo: Port Authority of New York and New Jersey.