After multiple changes to Libeskind’s original design of the Freedom Tower and prolonged disputes between the various parties involved over financing, Silverstein handed control over the building’s development to the Port Authority in 2006, and construction of the tower began in earnest after that date. In 2009, the Freedom Tower was officially renamed 1 World Trade Center, perhaps in response to concerns that the original name would make too tempting a target for future terrorist attacks. After years of sluggish progress, the rebuild effort quickened significantly in 2010, with 1 World Trade Center reaching the halfway point of its final height (693 feet above street level) by December. The tower is expected to be completed in 2013.
As for the rest of the complex, a new tower at 7 World Trade Center, rebuilt on the site of a 47-story building that was the last to collapse on 9/11, opened in 2006. The $2 billion 4 World Trade Center, located at the southeast corner of the site, will house more than 50 floors of office space and five stories of retail space; it is scheduled to be completed in late 2013. An ambitious glass and steel transit concourse, designed by the Spanish architect Santiago Calatrava and expected to cost nearly $3.5 billion, is scheduled for completion in late 2014, while Silverstein’s 2 and 3 World Trade Center will be completed sometime after 2015.