On Sept. 11, 2001, Siller was off-duty and on his way to meet his brothers when he learned of the attacks on the World Trade Center towers.
He turned the truck around and raced towards the danger, but was stopped at the Brooklyn Battery Tunnel.
Siller couldn't be deterred from his date with destiny and his duty to save lives.
He strapped 60 pounds of gear on his back and ran through the tunnel and into history.
"I'm sure he was running and saying, 'God, I have children,' but his job was to save people and that overcame everything," Siller's brother, George, said.
"When the building went down, I turned to my mother-in-law and I said, 'Nancy, I think I just lost my brother,'" Siller's brother, Frank, said.
Siller and 342 of his firefighting brethren perished on that fateful day, along with close to 3,000 Americans, drawing our country into war.
The run, which is expected to raise $2 million for charity, retraces Siller's footsteps. When it first started, the race drew 2,000 people, this year there will be 30,000.
When runners exit the tunnel this weekend, they'll see the faces of the firefighters killed on 9/11.
"We have 343 firefighters holding the pictures of their brothers they lost that day," said Frank Siller, who founded the Stephen Siller Foundation in honor of his brother.
Stephen Siller is a modern day hero and an inspiration to many.
"We want to make sure we don't forget, but we also want to make sure that we do good in their name and in his name," Frank Siller said.
The foundation's Building for America's Bravest program constructs smart homes for the most critically wounded soldiers. Each smart home is custom built for each of their specific needs.
"This house all being one story that is just one story makes it 100% easier just day-to-day things," said one veteran, who received one of the homes.
"That's exactly what we're trying to do, give back some of their independence that they lost by keeping our country so independent and free," Frank Siller said.
The Tunnel to Towers run will be telecast on CBS2 this Sunday at 10:30 a.m.
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