A U.S. flag flies on a building behind workers from the Ground Zero site as they prepare the final piece of One World Trade Center's spire to be lifted to the top of the building, in New York May 2, 2013. Crane operators hoisted the final pieces of the spire on Thursday, helping to fill the void in the New York City skyline that was left by the attacks of Sept. 11, 2001. Ironworkers will finish installing the spire, which weighs about 800 tons (725 metric tons) and is 400 feet (122 meters) tall, at a later date. REUTERS/Lucas Jackson (UNITED STATES - Tags: BUSINESS CONSTRUCTION POLITICS)