Construction will start with crews demolishing bedrock at the newly cleared sites, which have reminded residents of the Sept. 11, 2001, terrorist attacks for the past 6 1/2 years, the New York Post reported.

"There has not been this much going on at the site since the cleanup ended in 2002," said Silverstein, who held the World Trade Center property lease during the attacks and is now the lead developer in the site's reconstruction.

Port Authority Executive Director Anthony Shorris said there will be up to 10,000 workers on location in coming moths, calling the endeavor "an incredible construction machine."

Silverstein's Tower 3 and Tower 4 along with the Freedom Tower will be at there total height by 2010 and Silverstein's Tower 2 will reach its total height a year later.