Its architect, Glen Lee, is more than 90 years old, and for years he has shown up to the undeveloped lot off Mountain Creek Road nearly every day to twiddle with his strange creation, adjusting and expanding it a few hours at a time.
Many people in the neighborhood know Lee as "Stick Man," an eccentric who builds his fortress and tells war stories about his time as a rifleman in Germany during WWII.
"He's really sweet," said Brandi, an employee at the nearby Pizza Hut who asked that her last name not be used. "He came in here one time and I made him a pizza."
Lee welcomed passerby to visit and wander through the jumbled maze of passages, maybe even buy a handcrafted walking stick.
Brandi said several of her co-workers had been inside Lee's creation and he never charged them a dime for the treat, although he did have a small bucket for donations by the entrance. Anyone could walk through and wonder at the kind of person who could pour so much time and energy into such a daunting endeavor.
Now, only the exterior wall is standing, with an enormous pile of debris and wood collapsed in the center.
Whether this the work of vandals or nature is unknown, but Chattanoogans are already starting to mourn the loss.
Lucas Phillips, a sophomore at Red Bank High School, was walking by the site with a skateboard in hand and headphones in his ears Sunday afternoon when he stopped to look at what had happened.
He said he's never been inside himself, but knew plenty of people who had and thought it would be missed.
"I've seen people take their kids in there," he said. "It's just sad."
Andrew Auber said he was driving by on Sunday and saw Lee standing in the rain, surveying the ruin.
"He looked distraught," he said.
Lee was gone when a Times Free Press reporter and photographer stopped by Sunday afternoon.
Since his own father is a veteran, Auber said, the whole situation bothers him and he hopes the city or a group of volunteers will come together to replicate all of Lee's hard work. He said he's posted on Facebook about Lee and wants people to get behind the construction effort, whatever that may look like.
Looking ahead, one thing seems certain — if the Stick Man's fortress is ever going to be rebuilt or replicated, it will take the same painstaking time and care Lee put into it every day.
Stick by stick.