People come from all over the world for the special event.
On that day, Siller had just finished work and was on his way to play golf with his brothers, but when he heard on his scanner a plane hit the North Tower, he went back to Brooklyn Squad 1, got his gear and drove his truck to the Battery Tunnel which was closed for security. So he strapped on 60 pounds of gear, and ran through the tunnel to the Twin Towers, where he died saving others.
"It didn't surprise us on 9/11 that he did that. He got there. And as a family we just are so proud and we will never stop doing what we're doing," said his brother Frank Siller.
"We got together and helped raise a million and a half dollers and to me that was enormous. I didn't think we'd ever do anything bigger than that," said Stephen's sister Gina Siller Vogt.
To raise that money, thousands take part in Tunnel to Towers, retracing Stephen Siller's steps back on 9/11 from the foot of the Battery Tunnel to the Twin Towers.
The event also honors the 343 FDNY firefighters, 71 law enforcement officers and thousands of civilians who lost their lives that day.
Stephen was 34 years old. He left behind a wife and five children, and yet his brothers and sisters say he made everyone he met feel incredibly special.
"Every person at the wake said 'He's my best friend.' I'm not saying some people said 'I really felt like he was a good friend,' they're like 'I'm Stephen's best friend,'" said brother George Siller.
His memory lives on through the work of his family, and those who follow in his footsteps.
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