FILE- In this May 30, 2007 file photo, a steel column for the Freedom Tower bears signatures of Sept. 11 victims' family members at the World Trade Center in New York. Their signatures join those left by some who worked on the towers. Construction workers have left personal messages on One World Trade Center in the form of graffiti. (AP Photo/Mark Lennihan, File)

Associated Press
FILE- In this May 30, 2007 file photo, a steel column for the Freedom Tower bears signatures of Sept. 11 victims' family members at the World Trade Center in New York. Their signatures join those left by some who worked on the towers. Construction workers have left personal messages on One World Trade Center in the form of graffiti. (AP Photo/Mark Lennihan, File)
FILE- In this May 30, 2007 file photo, a steel column for the Freedom Tower bears signatures of Sept. 11 victims' family members at the World Trade Center in New York. Their signatures join those left by some who worked on the towers. Construction workers have left personal messages on One World Trade Center in the form of graffiti. (AP Photo/Mark Lennihan, File)