21. Looking West Over St. Paul's, Lower Manhattan.
(Photo: Mario Tama/Getty Images)
22. The north tower of New York's World Trade Center collapses after being struck by hijacked American Airlines Flt. 11, Tuesday, Sept. 11, 2001.
(AP Photo Richard Drew)
23. A man covered in dust walks in the street near the site of the World Trade Center towers in New York City, in this file photo taken early September 11, 2001. This year's anniversary of the September 11 attacks in New York and Washington will echo the first one, with silence for the moments the planes struck and when the buildings fell, and the reading of 2,792 victims' names.
(REUTERS/Shannon Stapleton-Files HB)
24. A rescue helicopter surveys damage to the Pentagon as firefighters battle flames after an airplane crashed into the U.S. military Headquarters outside of Washington in an apparent terrorist attack, September 11, 2001.
(REUTERS/Larry Downing LSD/HB)
25. (Photo: Jose Jimenez/Primera Hora/Getty Images)