Relatives of the victims descend on ground zero in Lower Manhattan, and the events of that terrible day and the weeks, months and years that followed are never forgotten, nor are the memories of those killed by terrorists in hijacked planes.
Additionally, we remember all those who have died from 9/11-related illnesses from their heroic work at ground zero and those who suffer today.
PHOTOS | 9/11 attacks on the World Trade Center in New York City
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.
RELATED | 'Eyewitness to 9/11: Behind the Lens' reveals untold stories, rare video of America's darkest day
In the photo gallery above, see images from the aftermath of the terror attacks, from missing posters hung by the hundreds across the city to candlelight vigils held across the country.
CLICK HERE for more Eyewitness News reflections, photos and stories marking the anniversary of 9/11
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