In the years after the Sept. 11 attacks, New York City began to rebuild a devastated Lower Manhattan.
In just nine years, One World Trade rose into the skyline, a symbol of New York City's resilience. Ground Zero itself became a memorial that welcomes thousands of visitors each year, commemorating the country's shared loss and grief from that day.
In Shanksville, Pennsylvania, family members of the victims of Flight 93 return annually to the point of impact to remember their loved ones. In Washington D.C., the damaged and burned Pentagon was rebuilt and made whole.
In the images below, see how the locations have been revived and the people have rebounded.
Photos over the span of the last four decades show how the skyline of lower Manhattan changed before and after the Sept. 11 terrorist attacks.
Satellite images of the Pentagon, taken across the span of two decades, show the damage and rebuild after the Sept. 11 attacks.
The point of impact just outside Shanksville, Pennsylvania, where Flight 93 dove into the ground after its passengers decided to fight against their hijackers was developed into a national memorial to grieve, to learn and to remember the heroism of those passengers on that day. On right, then-Presidential nominee Joe Biden visits the site on the 19th anniversary of 9/11. He is expected to visit again for the 20th anniversary.
Firefighters and other first-responders ran toward ground zero on Sept. 11, 2001. Now, who reported to the scene in New York continue to suffer from health effects like asthma, cancer, post-traumatic stress and substance abuse 20 years after the attacks.
Those who were at Ground Zero and other surrounding areas of lower Manhattan had to evacuate by bridge, tunnel or ferry. Now, visitors and locals once again flock to the city's iconic bridges for regular commutes and tourist photos.
Images taken over the span of twenty years show lower Manhattan before, during and after the attacks.
The Twin Towers, immortalized in countless photos and movies based in New York, was one of the city's most recognizable landmarks. One World Trade, which was built in just nine years, has since become the new icon of resilience for New Yorkers.
Development on ground zero is not completely finished – Two World Trade Center remains under construction, as well as a Performing Arts Center planned between Two World Trade and One World Trade.
Ground zero – the site where the Twin Towers once stood – has been transformed into a museum and memorial in memory of the 2,753 victims of the attack.
Brookfield Place, a mall and office complex across the street from the World Trade Center site, was heavily damaged due to its proximity to ground zero.
Areas closest to ground zero such as West Street, seen above, were scenes of complete damage due to debris from the attacks. Today, this area hosts Liberty Park – an extension of the Sept. 11 memorial space that is also home to The Sphere.
Many of the buildings closest to ground zero have been torn down and replaced by newer structures. Others, like the Church Street U.S. Postal Service station (left), cleared out debris left behind by the attacks and resumed operations.
Design and development by Nelson Hsu.
Editing by Andrew V. Pestano.