In a deal announced Wednesday by the Port Authority and One World Trade's developer, the U.S. General Services Administration has agreed to lease six floors of the city's tallest building when it opens next year.

The administration will occupy about 270,000-square-feet in the tower for at least two decades.

Other companies that have signed leases in the building include Conde Nast, which is renting 1.2 million-square-feet, and the Vantone China Center, which is leasing 190,000-square-feet.