Firefighters and civilians alike climbed 110 flights of stairs at the Gaylord National Convention Center at National Harbor in Maryland Sunday to honor New York Firefighters lost at the twin towers on Sept. 11, 2001.

The 9/11 Memorial Stair Climb is an annual event in multiple cities that supports the National Fallen Firefighters Foundation. As each participant completed the 110 flights, or 2,220 steps, a single bell was rung with the name of a fallen hero read aloud.

The 110 flights represents the floors of the twin towers that 343 New York firefighters were responding to when they were lost on 9/11.

“Every single participant has a fallen firefighter from that day clipped to their chest,” said Prince George’s County Fire Chief Tiffany Green. “And so they’re climbing in memory of those individuals. I think there’s a somber remembrance that exists.”

Alan Doubleday, a retired firefighter and public information director for the event, said this annual event brings up personal memories.

“I was actually working that day as a firefighter for Prince’s George’s County. And it’s a day we’ll never forget.” said Doubleday.

Some at Sunday’s event were wearing full firefighter gear as they made the climb to feel what it may have been like for those who gave their lives on 9/11.

Green said that those climbing the stairs on Sunday were encouraging other participants to keep going.

“The biggest part was the camaraderie in the stairs, watching people push through,” Green said. “Especially seeing the firefighters in the gear.”