The Tunnel to Towers Foundation is a nonprofit organization established in 2003 to honor the memory of FDNY firefighter Stephen Siller, who lost his life on September 11, 2001. The Foundation's mission is to support military personnel, veterans, and first responders by providing mortgage-free homes to Gold Star families and families of fallen first responders with young children. It also builds specially adapted smart homes for catastrophically injured veterans and works to eliminate veteran homelessness across the country.

The Foundation's core program, the In the Line of Duty Program, has committed over $1 billion to its initiatives, delivering mortgage-free homes and educating the public about 9/11 through its 9/11 Institute and mobile exhibits. The organization maintains high operational efficiency, directing a significant portion of its funds to its programs. With a dedicated staff and strong financial backing, the Tunnel to Towers Foundation continues to make a meaningful impact in the lives of those it serves.