Jud Box has spent eight years coping with the death of his firefighter son at the World Trade Center — but that didn’t prepare him for what he saw posted to a new online archive of photos and videos about the Sept. 11 terrorist attacks.

Scrolling through the archive, Box came face to face with his son, Gary Box, a firefighter with Brooklyn’s Squad 1, who was captured by a digital camera lugging his gear through a traffic-clogged Brooklyn-Battery Tunnel on his way to Ground Zero.

It’s the last known photo of Gary Box, then 35, who died an hour later in the toppling towers. His remains were never recovered.

“I walked out of the room and fell on the floor,” the elder Box said of discovering the photo in the online archive being assembled by the World Trade Center Memorial Museum, which has collected 3,000 images and videos in just two months.

“It was a shock emotionally, yet a blessing to find this photo,” says Box, 66, now of Weirsdale, Fla. His voice quaking with emotion from recounting his discovery of the photo, Box said he can no longer bring himself to look at it.

“It’s like looking at a walking dead man. You know what happened to him within 45 minutes,” he said.

The Web site, called Make History Happen, was launched around Sept. 11 of this year as a way to collect images related to the World Trade Center.

Memorial Foundation President Joseph Daniels said 9/11 is the most photographed event of our time — perhaps in all of history — and that collecting those still and moving images is an important part of understanding the historic event.

Gary Box, who was among 12 members of Squad 1 to die at the World Trade Center, was a five-year veteran of the department. He was married, with two children when he died working as a firefighter — the job he had dreamed of since he was a kid.

Although he can no longer look at the photo of his son in turnout gear walking through the tunnel, his firetruck in the background, Box said he’s grateful it’s there.

“It meant more than words can describe for me to have access to what is probably the last photo taken of my son,” Box said.

Contributions of photos, video or written stories can be submitted to http://www.makehistory.national911memorial.org.

tom.topousis@nypost.com

