When the terrorist attacks at the World Trade Center in New York happened on September 11, 2001, West Metro Fire firefighter Brad Harmon was sitting in a classroom for paramedics school. He was sent home from class, but his day was far from over.

Harmon served in the U.S. Air Force at the time, and he was sent to the Buckley Air Force Base in Aurora where he stayed the night.

“Life stops. I remember the surealness of it,” said Harmon. “I remember how scary that night was. Everybody thought the next attack was coming to that base that night. We were on full alert.”

Harmon joined 2,500 others the morning of Sept. 11 to pay tribute to the 343 FDNY firefighters and the nearly 3,000 Americans who died on 9/11. Him, other firefighters from multiple fire departments and residents climbed the equivalent of the 110 stories of the World Trade Center at Red Rocks.

Before the climb ensued, recordings from New York news stations from when the attacks occurred were played, music from the Colorado Emerald Society was performed and the Honor Bell was rung to pay homage to those who died 18 years ago.

“I still see those buildings being hit by a plane. Can you imagine (the firefighters) going up into those buildings, and what it took,” said Durant Carpenter of Centennial.

It was the 11th year the climb at Red Rocks took place. The event benefits the FDNY Counseling Services Unit and the programs provided by the National Fallen Firefighters Foundation to support the families of our nation's fallen. Organizers say more than $1 million is raised each year.

"It not only took so many lives, but it took a symbol of who we were in our way of life. You can't forget that sort of thing,” said Michelle Malin, executive director of the Honor Bell Foundation who brought the Honor Bell to Red Rocks. “If you forget then we lose our reason to fight for the way of life we have.”