Walker attributed the interest in the tunnels to their intrigue, especially for those who don’t spend much time downtown.

A crowd favorite is a cramped, U-shaped tunnel that connects the Philcade and Philtower buildings.

The tunnel is locked behind a heavy, white metal door that opens using a series of weights and chain pulleys. Inside, the walls are bare with peeling paint. The ceiling, at its peak, is about 6 feet high.

Rumor has it that oil baron Waite Phillips, for whom both buildings were built and named, used the tunnels to safely cross between the two sites at a time when kidnappings of wealthy businessmen were on the rise.

Both the tunnel’s creepy facade and historical connection, Walker believes, draws people to it.

“I think it takes Tulsa and links it to something most people hear about in history,” Walker said.

The 80-foot tunnel sparked Dave and Callie Burlin’s curiosity during Saturday’s tour. Callie Burlin said she enjoyed going through that tunnel because it’s one of the few not normally open to the public.

“It’s just really fun to learn about Tulsa and about the oil industry and where we started,” she said.