And for two survivors from Raleigh, it's a day that always causes them to pause and reflect.
As a new NC State grad, John Cerqueira was living his dream living and working in New York.
He was just about ten floors below where the plane hit the World Trade Center where he was working.
"We had no idea either of the buildings were at the risk of collapsing," Cerqueira says.
He did know he needed to make it down 80 flights of stairs. Along the way, he and his boss came across a woman in a wheelchair.
"We asked if we could help and she said yes."
Running on adrenaline, together they carried her down.
"There was just an intense focus on escaping," Cerqueira said.
They made it help, escorting the woman to an ambulance just minutes before the building collapsed. John remembers seeing the empty skyline.
"It just looked like someone had taken an eraser out of a picture that had been seared into our consciousness," he says.
Cerqueira moved back to North Carolina, and eventually started a family, and is now running for Raleigh City Council.
Meanwhile, Mike Dempsey was working at Credit Suisse and also survived.
"There's no closure, I said this many times and still say it 23 years later actually it gets harder and harder every year as you get older," he says.
He now lives in Raleigh, but each year he tries to return to New York to visit the memorial. Today, he was in the city to work with Cantor Fitzgerald to honor those lost in the tower and support charities at their annual event.
"Giving back is something that takes a dark day and turns it into something very inspiring," Dempsey says.
And for Cerqueira, giving back also means sharing what happened, so people never forget.
"It felt like that was my obligation for being spared and being able to tell that story."
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