By Tori Mason

DENVER (CBS4)– Hundreds of firefighters in Colorado gathered on 9/11 to honor fellow firefighters who died 16 years ago.

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Many firefighters climbed the stairs at different locations in full bunker gear while carrying a fallen firefighter’s photo. The effort is to honor the 343 FDNY firefighters killed in the 9/11 attacks.

(credit: CBS)

The Transamerica Tower is one of the tallest buildings in downtown Denver and it only stands half as high as the Twin Towers. Denver firefighters climbed the building’s 55 flights of stairs, went back down and climbed 55 flights again to experience what first responders accomplished on 9/11.

(credit: CBS)

(credit: CBS)

Red Rocks is home to the largest 9/11 Memorial Stair Climb in the country. More than 2,000 people from 16 states climbed the amphitheater Monday morning, alongside firefighters from 60 departments.

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Participants at Red Rocks climbed the stairs and walked nine laps around the amphitheater, the equivalent of the World Trade Center’s 110 stories.

Many of the firefighters climbing were too young to remember the events of 9/11, but they honor their brothers’ sacrifice in every step.

“The fire service made a promise to never forget. We’re keeping our promise,” said Aurora Firefighter Jacob Wilmes.

This year’s event raised over $63,000 for family support programs provided by the National Fallen Firefighters Foundation.

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Tori Mason is an award-winning reporter for CBS4 This Morning. Follow her on Twitter @ToriMasonTV.