Unforgettable 9/11 Images(01 of23)
Open Image ModalIn this Sept. 11, 2001 file photo, United Airlines Flight 175 approaches the south tower of the World Trade Center in New York shortly before collision as smoke billows from the north tower. (credit:Carmen Taylor, AP)
Unforgettable 9/11 Images(02 of23)
Open Image ModalA hijacked commercial plane approaches the World Trade Center shortly before crashing into the landmark skyscraper Sept. 11, 2001 in New York. (credit:Seth McAllister, AFP / Getty Images)
Unforgettable 9/11 Images(03 of23)
Open Image ModalHijacked United Airlines Flight 175 from Boston crashes into the south tower of the World Trade Center and explodes at 9:03 a.m. on September 11, 2001 in New York City. (credit:Spencer Platt, Getty Images)
Unforgettable 9/11 Images(04 of23)
Open Image ModalPedestrians on the waterfront in Brooklyn, New York, look across the East River to the burning World Trade Center towers Sept. 11, 2001 after a terrorist attack. (credit:Henry Ray Abrams, AFP / Getty Images)
Unforgettable 9/11 Images(05 of23)
Open Image ModalA helicopter flies over the Pentagon in Washington, Tuesday, Sept. 11, 2001 as smoke billows over the building. The Pentagon took a direct, devastating hit from an aircraft and the enduring symbols of American power were evacuated. (credit:Heesoon Yim, AP)
Unforgettable 9/11 Images(06 of23)
Open Image ModalSmoke comes out from the Southwest E-ring of the Pentagon building September 11, 2001 in Arlington, Va., after a plane crashed into the building and set off a huge explosion. (credit:Alex Wong, Getty Images)
Unforgettable 9/11 Images(07 of23)
Open Image ModalOfficials examine the crater Sept. 11, 2001 at the crash site of United Airlines Flight 93 in Shanksville, Pennsylvania. (credit:David Maxwell, AFP / Getty Images)
Unforgettable 9/11 Images(08 of23)
Open Image ModalPhoto dated Sept. 11, 2001 shows US President George W. Bush being informed by his chief of staff Andrew Card of the attacks on the World Trade Center in New York during an early morning school reading event in Sarasota, Florida. (credit:Paul J. Richards, AFP / Getty Images)
Unforgettable 9/11 Images(09 of23)
Open Image ModalA person falls from the north tower of New York's World Trade Center Tuesday Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center and brought down the twin 110-story towers. (credit:Richard Drew, AP)
Unforgettable 9/11 Images(10 of23)
Open Image ModalThe south tower of New York's World Trade Center collapses Tuesday Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (credit:Richard Drew, AP)
Unforgettable 9/11 Images(11 of23)
Open Image ModalIn this Tuesday, Sept. 11, 2001 file photo, people run from a cloud of debris from the collapse of a World Trade Center tower in New York. (credit:Suzanne Plunkett, AP)
Unforgettable 9/11 Images(12 of23)
Open Image ModalA firefighter breaks down after the World Trade Center buildings collapsed September 11, 2001 after two hijacked airplanes slammed into the twin towers in a terrorist attack. (credit:Mario Tama, Getty Images)
Unforgettable 9/11 Images(13 of23)
Open Image ModalThis September 11, 2001 file photo shows Marcy Borders covered in dust as she takes refuge in an office building after one of the World Trade Center towers collapsed in New York. Borders was caught outside on the street as the cloud of smoke and dust enveloped the area. The woman was caught outside on the street as the cloud of smoke and dust enveloped the area. (credit:Stan Honda, AFP / Getty Images)
Unforgettable 9/11 Images(14 of23)
Open Image Modal A man with a fire extinguisher walks through rubble after the collapse of the first World Trade Center Tower September 11, 2001, in New York. The man was shouting as he walked looking for victims who needed assistance. (credit:Doug Kanter, AFP / Getty Images)
Unforgettable 9/11 Images(15 of23)
Open Image ModalAn unidentified woman reacts moments after watching both of the nearby World Trade Center towers collapse Tuesday, Sept. 11, 2001, in New York. She was among the residents of the nearby Battery Park City apartment complex waiting to be evacuated from the area. (credit:Quyen Tran, AP)
Unforgettable 9/11 Images(16 of23)
Open Image ModalIn this Tuesday, Sept. 11, 2001 file photo, rubble and ash fill lower Manhattan streets after two hijacked airliners were crashed into the towers of the World Trade Center in New York, collapsing them. (AP Photo/Boudicon One) (credit:Boudicon One, AP)
Unforgettable 9/11 Images(17 of23)
Open Image ModalThis NASA Landsat image taken on Sept. 11, 2001 shows that the damage and smoke from the terrorist attacks could be seen from space. (credit:NASA)
Unforgettable 9/11 Images(18 of23)
Open Image ModalA view of the remains of an ambulance in front of the Millenium Hotel at Ground Zero after the collapse of both towers of the World Trade Center following the terrorist attacks on September 11, 2001 in New York, New York, USA. (credit:Justin Lane, Corbis)
Unforgettable 9/11 Images(19 of23)
Open Image ModalThe rubble of the World Trade Center smoulders following a terrorist attack Sept. 11, 2001 in New York. (credit:Alex Fuchs, AFP / Getty Images)
Unforgettable 9/11 Images(20 of23)
Open Image ModalFirefighters raise a U.S. flag at the site of the World Trade Center after two hijacked commercial airliners were flown into the buildings September 11, 2001 in New York. (credit:The Record / Getty Images)
Unforgettable 9/11 Images(21 of23)
Open Image ModalThe sky glows orange as the sun rises over the damaged side of the Pentagon with the US Capitol behind in Washington, DC, 13 September, 2001. (credit:Luke Frazza, AFP / Getty Images)
Unforgettable 9/11 Images(22 of23)
Open Image ModalU.S. President George W. Bush speaks to rescue workers, firefighters and police officers from the rubble of Ground Zero September 14, 2001 in New York City. (credit:Eric Draper, White House / Getty Images)
Unforgettable 9/11 Images(23 of23)
Open Image ModalPhoto dated Sept. 11, 2001 shows firefighters making their way through the rubble of the World Trade Center in New York after two hijacked planes flew into the landmark skyscrapers. (credit:Doug Kanter, AFP / Getty Images)