9/11: Then and Now

NYC Skyline 2001: The twin towers of the World Trade Center burn behind the Empire State Building in New York, Sept. 11, 2001. Credit: AP Photo/Marty Lederhandler

Trinity Church 2001: Ash covers gravestones in Trinity Church on Sept. 11, 2001 after the attacks on the nearby World Trade Center towers in New York. Credit: AP Photo/John Labriola

Trinity Church 2011: The courtyard and graveyard at Trinity Church in Lower Manhattan nearly 10 years after the attacks on the Twin Towers, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Greenwich Street 2011: The intersection of Greenwich and Rector Streets, looking north to where 2 World Trade Center once stood, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Church and Dey Streets 2011: The new subway station on Church and Dey Streets nearly 10 years later, as construction continues across the street at the World Trade Center site, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Greenwich Street 2001: Debris from the collapse of the World Trade Center towers covers Greenwich Street near Rector Street on Sept. 11, 2001. Credit: AP Photo

Brooklyn 2001: The south tower begins to collapse as smoke billows from both towers of the World Trade Center, in New York, Sept. 11, 2001. Credit: AP Photo/Jim Collins

Church and Dey Streets 2001: A subway entrance is covered in debris at the intersection of Church and Dey Streets after the World Trade Center collapse in New York City on Sept. 11, 2001. Credit: AP Photo

West Street 2011: The skyline of lower Manhattan Sunday, Sept. 4, 2011, where the towers of the World Trade Center stood is still under going construction all around the area. Credit: Gordon Donovan/CBSNews.com

Liberty Street 2001: Firefighters and urban rescue workers work at the site of collapsed World Trade Center towers after the terrorist attacks in New York, on Sept. 19, 2001. Credit: AP Photo

Brooklyn 2011: The skyline of lower Manhattan across the East River near the Brooklyn Bridge, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Fulton Street 2001: People run from a cloud of debris from the collapse of a World Trade Center tower in New York on Tuesday, Sept. 11, 2001. Credit: AP Photo/Suzanne Plunkett

Fulton Street 2011: Construction is still underway on Fulton Street looking west towards the where the towers of the World Trade Center once stood, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

West Street 2001: The north tower of New York's World Trade Center collapses after being struck by hijacked American Airlines Flt. 11 on Sept. 11, 2001. Credit: AP Photo/Richard Drew

Brooklyn Bridge 2011: Pedestrians cross the Brooklyn Bridge, with the lower Manhattan skyline in the background, on Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Beekman Street 2001: Pedestrians on Beekman Street flee the area of the collapsed World Trade Center towers in lower Manhattan following the terrorist attacks on the New York landmarks on Sept. 11, 2001. Credit: AP Photo/Amy Sancetta

Beekman Street 2011 A couple passes the parking garage on Beekman Street in New York, Sunday, Sept. 4, 2011, the area that was choked by smoke and dust after the collapse of the World Trade Center towers in 2001. Credit: Gordon Donovan/CBSNews.com

Park Row 2001: Pedestrians on Park Row flee the area of the World Trade Center as the center's south tower collapses following the terrorist attack on the New York landmark on Sept. 11, 2001. Credit: AP Photos/Amy Sancetta

NYC Skyline 2011: The Empire State Building dominates the New York skyline on Sept. 5, 2011. Credit: Gordon Donovan/CBSNews.com

Brooklyn Bridge 2001: Women wearing dust masks flee across New York's Brooklyn Bridge from Manhattan to Brooklyn following the collapse of both World Trade Center towers on Sept. 11, 2001. Credit: AP Photo/Mark Lennihan

Park Row 2011: Traffic heads north towards the Brooklyn Bridge on New York's Park Row, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Murray Street 2001: A piece of debris, possibly from one of the crashed airliners, lies on the corner of Murray Street in lower Manhattan near the World Trade Center site in New York on Sept. 11, 2001. Credit: AP Photo/Chris Kline

Murray Street 2011: All debris has been cleared away on the corner of Murray Street in lower Manhattan near the World Trade Center site, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Cortlandt Street 2001: With the skeleton of the World Trade Center twin towers in the background, New York City firefighters work amid debris on Cortlandt Street after the terrorist attacks on Sept. 11, 2001. Credit: AP Photo/Mark Lennihan

Cortlandt Street 2011: Looking down Cortlandt Street in New York on Sunday, Sept. 4, 2011, just steps from where the World Trade Center stood. Credit: Gordon Donovan/CBSNews.com

Fulton Street 2001: Survivors of the World Trade Center terrorist attacks make their way through smoke, dust and debris on Fulton St., about a block from the collapsed towers on Sept. 11, 2001, in New York. Credit: AP Photo/Gulnara Samoilova

Fulton Street 2011: People make their way along Fulton Street along St. Paul's Church near the World Trade Center site, Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com

Liberty Street 2011: The view of the construction of new buildings where the World Trade Center once stood continues Sunday, Sept. 4, 2011. Credit: Gordon Donovan/CBSNews.com