World Trade CenterThe World Trade Center towers in Lower Manhattan were eviscerated from the New York City skyline following the Sept. 11, 2001 attacks.
Ground ZeroA U.S. flag flies near the base of the destroyed World Trade Center in New York, September 11, 2001. Planes crashed into each of the two towers, causing them to collapse
AftermathSmoke from the remains of New York's World Trade Center shrouds lower Manhattan as a lone seagull flies overhead in a photograph taken across New York Harbor from Jersey City, New Jersey September 12, 2001. Each of the twin towers were hit by hijacked airliners and collapsed in one of numerous acts of terrorism directed at the United States on September 11, 2001
George W. Bush Visits Ground ZeroStanding atop rubble with retired New York City firefighter Bob Beckwith Friday, Sept. 14, 2001, then-President George W. Bush rallies firefighters and rescue workers during an impromptu speech at the site of the collapsed World Trade Center in New York City.
FirefighersNew York City fire fighters hold a giant U.S. flag on September 11, 2007, that was damaged during the Sept. 11, 2001 attacks during a ceremony marking the sixth anniversary of the tragedy in New York.
Victims' FamiliesFamilies of victims walk into ground zero during ceremonies marking the sixth anniversary of the September 11, 2001 attacks at the World Trade Center site in New York September 11, 2007.
Ground ZeroA U.S. flag flies from a crane over the Ground Zero site during a ceremony commemorating the seventh anniversary of the September 11 attacks, in Zuccotti Park in New York September 11, 2008.
Freedom TowerA construction worker signs his name on one of the first steel beams of the new Freedom Tower being constructed on the site of the the former World Trade Center in New York September 11, 2007.
"Tribute in Lights"Actress Bebe Neuwirth speaks near the "Tribute in Lights" in lower Manhattan on the 10th anniversary of the 9/11 attacks on the World Trade Center, in New York September 11, 2011
Freedom TowerLower Manhattan skyline with 1 World Trade Center decked in red-white-and-blue (left), with Statue of Liberty (center) next to the Tribute in Light (right), September 2011.
The Sept. 11 attacks changed the landscape of New York City forever. Before 9/11, you could view the World Trade Center towers by crossing the Brooklyn Bridge or hitching a ride on the Staten Island Ferry.
After the 2011 terrorist attacks, the site became known as Ground Zero, and where the towers once stood became a gaping hole in the ground and a symbol of the destruction.
As the country prepares to mark the 12th anniversary of 9/11, the reconstruction in Lower Manhattan is nearing completion. Progress has been made on One World Trade Center, also known as the Freedom Tower.
The 104-story building, set to be completed later next year, is symbolic of America's resilience in the aftermath of 9/11. The Freedom Tower will be 1,776-feet high -- a nod to the year of our nation's founding.
Click through the slideshow above to view iconic photos of past ceremonies marking the anniversary of 9/11 -- from the poignant shot of then-President George W. Bush picking up a megaphone alongside a firefighter at Ground Zero -- to a glittering Freedom Tower from last year's ceremony. There are also shots of the World Trade Center, pictures of Ground Zero in the days following the 9/11 attacks and loved ones remembering the victims.