The Folly’s rooms were connected by a maze of corridors and staircases, embedded with a network of ventilation shafts, fireplaces and flues to enable Körner's heating and ventilation system.

“He was way ahead of his time in terms of engineering, installing a ventilation system with underground tunnels to enable the cool air to rise through the same system that pulled the heat through the fireplaces,” Connie Russell from Körner’s Folly Foundation told PBS North Carolina. Hence the existence of trap doors and passages to maintain the system.

“I have fond memories of just wandering around the house,” says Bill Donnell, a Körner descendant. “It was a treasure trove of places to hide. It was an adventure just to find out where the tunnels led to. Every room sparked the imagination.”

Inside the eccentric historical house dubbed 'the strangest in the world'