The 9/11 Tower Challenge returns to Glendale, and registration is now open.

The World Trade Center’s Twin Towers each consisted of 110 floors and 2071 steps, and each year thousands of people across Arizona walk, climb and run the stairs to remember. Firefighters in full gear, police, military and bomb squad personnel march steadily alongside civilians of varying ages, abilities and backgrounds to represent the 110 flights of stairs climbed by New York City firefighters during the attacks on the World Trade Center and in honor of those who lost their lives.

Participants of the 9/11 Tower Challenge in Glendale walk up and down the steps at Gila River Arena, 9400 W. Maryland Ave., starting at 8 a.m. Saturday, Sept. 10.

Last year more than 1,500 participants took part in Glendale. Photographs of fallen heroes line the stairs, and participants pause briefly to read the names in recognition of the sacrifice each made while in the service of others.

Proceeds benefit The 100 Club of Arizona, which supports all police, correctional, probation and parole officers, firefighters, and federal agents who are serving and protecting Arizonans. This includes all county, tribal, state and federal levels.

While the event’s pace varies based on experience level, organizers see the trek taking anywhere from 30 minutes at best to an hour at most, but the majority of attendees complete it within 45 minutes.

Click here to register.

Arriving 30 minutes early is recommended.

Registrations end Wednesday, Aug. 31 or when event capacity is reached. If available, late registration will go Sept. 1-6.