In the video player above, watch firsthand accounts from those who were in Lower Manhattan on that fateful day, with commentary from then-anchor Bill Beutel. (Warning: This contains images that some may find disturbing.)
Each year, 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.
RELATED | 'Eyewitness to 9/11: Behind the Lens' reveals untold stories, rare video of America's darkest day
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.
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.
RELATED | How reporter N.J. Burkett and his photographer escaped Twin Towers collapse
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.
CLICK HERE for Eyewitness News reflections, photos and stories marking the anniversary of 9/11
* Get Eyewitness News Delivered
* Follow us on YouTube
* More local news
* Send us a news tip
* Download the abc7NY app for breaking news alerts Submit a News Tip