September 11, 2001 -- September 11, 2006

Cloaked in ash, pedestrians on Beekman Street in lower Manhattan flee the World Trade Center site.

An American flag flies from a makeshift altar overlooking the site where United Airlines flight 93 crashed in Shanksville, Pennsylvania.

The facade of the Pentagon building shows little trace of the attack.

The north tower of New York's World Trade Center collapses after being struck by hijacked American Airlines flight 11.

The twin towers of the World Trade Center burn behind the Empire State Building.

Coated in dust, survivors make their way to safety.

The Brooklyn Bridge is arguably the best location to take in the Manhattan skyline.

Hijacked American Airlines flight 77 crashed into the Pentagon building near Washington, DC.

Women wearing dust masks flee across the Brooklyn Bridge from Manhattan to Brooklyn following the collapse of both World Trade Center towers.

The gaping void left by the World Trade Center is the future site of the Freedom Tower.

Pedestrians flee as the World Trade Center's south tower collapses.

The parking garage on Beekman Street is once again in service for business people and visitors.

The Empire State Building now dominates the New York skyline.

Thousands of shoppers, tourists and business people pass by Ground Zero every day.

With the skeleton of the Twin Towers in the background, New York City firefighters work amid debris on Cortlandt Street just after the terrorist attacks.

Many visitors make their way to the World Trade Center site via Fulton Street, to get a glimpse of Ground Zero and pay their respects.

An American flag serves as a memorial to those killed in UA flight 93 on Sept. 11, 2001.

The skyscrapers surrounding Park Row can't compare to the massive shadow the World Trade Center had cast.