On Saturday, New Yorkers and the rest of the nation will mark 20 years since the day that forever changed our world.
The Tribute in Light was first presented six months after 9/11 and then every year thereafter, from dusk to dawn, on the night of September 11.
RELATED | Photos: Up close look at the World Trade Center's 9/11 'Tribute in Light'
It has become an iconic symbol that both honors those killed and celebrates the unbreakable spirit of New York.
The installation is assembled on the roof of the Battery Parking Garage south of the 9/11 Memorial.
CLICK HERE for more Eyewitness News reflections, photos and stories marking the anniversary of 9/11
The twin beams reach up to four miles into the sky and are comprised of 88 7,000-watt xenon lightbulbs positioned into two 48-foot squares, echoing the shape and orientation of the Twin Towers.
The installation can also be viewed from a 60-mile radius around lower Manhattan.
September 11 still shapes American policy, politics and everyday experiences in places from airports to office buildings, even if it's less of a constant presence in the public consciousness after 20 years.
The 9/11 commemorations are by now familiar rituals, but each year at ground zero, victims' relatives infuse the ceremony with personal messages of remembrance, inspiration and concern.
We remember all those who have died from 9/11-related illnesses from their heroic work at ground zero and those who suffer today.
RELATED | PHOTOS: 9/11 Tribute in Light through the years