New World Trade Center skyscraper named tallest building in the US The skyscraper at New York's World Trade Center has been designated the tallest building in the United States by virtue of its spire, surpassing Chicago's Willis Tower, the Council on Tall Buildings and Urban Habitat has said. The council's Height Committee ruled the mast atop the building known as One World Trade Center was a spire and therefore a permanent feature of the buiding, rather than an antenna, which would be considered functional equipment and subject to change. With the spire, One World Trade Center reaches 1,776 feet compared with 1,451 feet (442 metres) for the Willis Tower, formerly known as the Sears Tower. Counting its antena, the Willis Tower reaches 1,729 feet. The council's Height Committee convened a group of 25 architects, engineers and facade consultants from around the world on Nov. 8 to consider the issue, and ultimately decided the mast is a spire, the council said. Because One World Trade Center is still incomplete, its designation will become official once the building is occupied in 2014, the council said. It is one of four skyscrapers planned at the site that had been destroyed by the attacks of Sept. It would then become the third largest building in the world after Dubai's Burj Khalifa at 2,717 feet and the Makkah Royal Clock Tower in Mecca, Saudi Arabia, at 1,972 feet. However, four other buildings under construction in China and one in South Korea would be taller than One World Trade Center, according to Emporis, a database for building information.