One thousand climbers rose to the challenge Sunday for the seventh annual Tower Climb at One World Trade Center, raising $1 million for first responders in need.

Sponsored by the Tunnel to Towers Foundation in honor of those felled in the Sept. 11, 2001, terror attacks, the event kicked off in the basement of the Freedom Tower — and ended 104 floors and more than 2,200 steps later atop the Big Apple skyscraper, according to reports.

“You think of the stories from that day, of firefighters in those stairwells saving people,” Frank Siller, T2T chairman and CEO, told Fox News on Sunday.

“They’re going up the stairs and everyone else is going down and outside the building,” Siller said. “It was the greatest rescue effort ever in America. Saved over 25,000 lives, but we lost so many great heroes that day and we’re here to honor those heroes and never forget.”

Tower climber Wai Ching was first to the top in this year’s event, CBS News reported.

The charity climb is personal for Siller. His brother, FDNY hero Stephen Siller, was heading home after a shift at Squad 1 in Brooklyn when hijacked airliners struck the Twin Towers.

The younger Siller turned around and ran into action lugging 60 pounds of equipment, giving his life in the rescue efforts when the towers collapsed, his brother said.

The foundation was created to honor Stephen and the nation’s other fallen heroes and has raised millions of dollars over the years through a series of national events, including an annual New York City 5K run.

The Tower Climb was started in 2015 and has become an annual tradition since.

“We wanted to honor what our little brother did that day, the act of heroism,” Frank Siller said. “So we started the Tunnel to Towers Foundation and we’ve built houses all over America for our catastrophically injured service members and first responders, and pay off mortgages for Gold Star widows and fallen first responders who’ve fallen in the line of duty that left kids behind.

“We have very simple goals,” he added. “Honor the sacrifice that Stephen did and never forget. And why not do good at the same time?”