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. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
The final piece of the spire is hoisted to the roof of One World Trade Center, Thursday, May 2, 2013 in New York. The piece will be attached to the spire at a later date, capping off the tower at 1,776 feet. (AP Photo/Mark Lennihan)
In this view from midtown Manhattan, cranes work on the rising spire on top of One World Trade Center, Thursday, April 25, 2013, in New York. (AP Photo/Mark Lennihan)