NEW YORK - APRIl 3: (SEPTEMBER 11 RETROSPECTIVE) The 'Tribute in Light' memorial to the World Trade Center is seen from the Empire State Building April 3, 2002 in New York City.

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NEW YORK, NY - AUGUST 25: Construction continues on One World trade Center (R) and the National September 11 Memorial & Museum (LOWER L) at the World Trade Center site on August 25, 2011 in New York City. The memorial features two reflecting pools on the footprints of the twin towers. The memorial is scheduled to be dedicated on September 11, 2011, the tenth anniversary of the World Trade Center …

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NEW YORK, NY - AUGUST 27: Mist shrouds the top of Freedom Tower, still under construction next to the September 11 Memorial and Museum and World Trade Center construction site, about 12 hours before Hurricane Irene is expected to arrive August 27, 2011 in New York City. The World Trade Center site is located inside the Zone A mandatory evacuation area but New York City Mayor Michael Bloomberg …

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NEW YORK - AUGUST 25: Construction cranes fill the air around Ground Zero in lower Manhattan as seen from the east August 25, 2010 in New York City. Work continues on the former World Trade Center site as activists have been lining up for and against a proposed Islamic cultural center and prayer room two blocks from the site.

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NEW YORK, NY - JANUARY 06: A view of Ground Zero is seen from the side of 1 World Trade Center January 6, 2011 in New York City. The tower has reached 52 floors, roughly halfway to its final height. Workers are adding nearly a floor a week to the building which will be the tallest in New York when it is completed in 2013.

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NEW YORK, NY - MAY 05: A view of construction at the World Trade Center site on May 5, 2011 in New York City. President Barack Obama is visiting Ground Zero today to participate in a wreath laying ceremony and to mark the death of Osama bin Laden.

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NEW YORK, NY - JANUARY 06: A construction supervisor walks down a stairwell on the eastern face of 1 World Trade Center January 6, 2011 in New York City. The tower has reached 52 floors, roughly halfway to its final height. Workers are adding nearly a floor a week to the building which will be the tallest in New York when it is completed in 2013.

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NEW YORK - FEBRUARY 15: (SEPTEMBER 11 RETROSPECTIVE) As the sun sets over New Jersey, cleanup and recovery efforts continue at the site of the World Trade Center disaster February 15, 2002 in New York City.

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WASHINGTON - OCTOBER 11, 2001: (SEPTEMBER 11 RETROSPECTIVE) U.S. President George W. Bush holds an American flag during a Memorial Service at the Pentagon October 11, 2001 in Arlington, Virginia.

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