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Members of the media and workers at the Ground Zero site take photographs as the final piece of a spire is lifted to the top of One World Trade Center, in New York May 2, 2013. The piece will be attached at a later date. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

A worker from Ground Zero attaches straps to the final piece of One World Trade Center's spire as it is prepared to be lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

An ironworker uses a line to steady the final piece of a spire, affixed with a U.S. flag, before it is lifted to the top of One World Trade Center in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The 408-foot spire is viewed as it is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. When bolted into place at a later date, the spire will make One World Trade Center the tallest building in the Western Hemisphere.The raising of the spire, which comes on the second anniversary of the death of Osama bin Laden, will make One World Trade Center 1,776 feet tall. One World Trade Center is built on the site where the September 11, 2001 attacks toppled the original World Trade Center towers. (Photo by Spencer Platt/Getty Images) ( 167929996 )

Construction workers watch as the 408-foot spire is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930220 )

Workers fit supports to the final two sections of a 408-foot spire that will be hoisted to a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930221 )

Construction workers watch as the 408-foot spire is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930222 )

The 408-foot spire is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930224 )

Construction workers watch as the 408-foot spire is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930229 )

People as the 408-foot spire is hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167930230 )

The 408-foot spire can be seen from the Brooklyn Promenade after it was hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167933133 )

The 408-foot spire is seen after it was hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167933151 )

The 408-foot spire is seen after it was hoisted onto a temporary platform on the top of One World Trade Center on May 2, 2013 in New York City. (Photo by Spencer Platt/Getty Images) ( 167933157 )

The final section of the spire that will top off One World Trade Center is raised past iron workers to the top of the building in New York, May 2, 2013. The piece will be attached at a later date. REUTERS/Gary Hershorn ( USA/ )

The final section of the spire that will top off One World Trade Center is raised past iron workers to the top of the building in New York, May 2, 2013. The piece will be attached at a later date. REUTERS/Gary Hershorn ( USA/ )

A U.S. flag flutters in the wind as the final piece of a spire is lifted to the top of One World Trade Center in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The final pieces of the spire for One World Trade Center are hoisted in New York, May 2, 2013. Crane operators hoisted the final pieces of the spire atop One World Trade Center on Thursday, helping to fill the void in the New York City skyline that was left by the attacks of Sept. 11, 2001. REUTERS/Shannon Stapleton ( USA-WORLDTRADECENTER/ )

A U.S. flag flutters in the wind as the final piece of a spire is lifted to the top of One World Trade Center in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The steeple of St. Paul's Chapel rises into the sky as the final piece of the building's spire is lifted to the top of One World Trade Center in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The final section of the spire that will top off One World Trade Center is raised to the top of the building in New York, May 2, 2013. REUTERS/Gary Hershorn ( USA-WORLDTRADECENTER/ )

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. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

Ground Zero workers attach straps to the final piece of One World Trade Center's spire as it is prepared to be lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

A U.S. flag flutters in the wind as the final piece of One World Trade Center's spire is lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

Pedestrians walk across a crosswalk in front of the final piece of One World Trade Center's spire, before it is lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

A woman and man (L) embrace as they watch the final piece of One World Trade Center's spire being lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

Ground Zero workers photograph with their phones as the final piece of One World Trade Center's spire is lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The final piece of One World Trade Center's spire is seen next to the base of the building before it is lifted to the top in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

A U.S. flag flies in the wind as the final piece of One World Trade Center's spire is lifted to the top of the building in New York, May 2, 2013. REUTERS/Lucas Jackson ( USA-WORLDTRADECENTER/ )

The top piece of the 408-foot spire for One World Trade Center is lifted to the top of the building in New York, Thursday, May 2, 2013. (AP Photo/Seth Wenig) ( APTOPIX World Trade Center Spire )

A worker holds a guide rope as the final piece of spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. (AP Photo/Mark Lennihan) ( APTOPIX World Trade Center Spire )

The final section of the spire that will top off One World Trade Center is raised past iron workers to the top of the building in New York, May 2, 2013. REUTERS/Gary Hershorn ( USA/ )