Midwest Mystery: Who built the underground city in Leavenworth?

Apparently, a street-scape project is erasing Leavenworth's history according to some . . .

Some speculate the underground town was created in the 1800s and could have been used during slavery or for fugitives . . . "I think it would just be kind of tragic if no one knew what it was or if no one cared," Lemons said.

Some people who've lived in Leavenworth their entire lives don't know anything about the underground city, and those who do don't know the historical significance.

True to form, KCTV5 doesn't really explain the significance of the "underground city" and since (like most reporters) I don't feel like performing a simple google search . . . I'm just gonna assume it was the Montauk Monster who is responsible for the whole thing.