http://www.landlinemag.com/Archives/200 ... round.html
I found this interesting. It appears MO. has a lot of them.
"It used to be that caves were the domain of a select few – brave explorers, coal miners, Batman.
These days, you can take walking tours and tram rides through many caves in the Midwest and South.
Heck, in some places, you can even drive a truck through them.
Missouri is one such place, loaded with caves that are used for underground storage, warehousing and even office space.
Drive down to Carthage and you can see the Carthage Underground, a 43-million cubic foot collection of marble quarries, most of which is owned by Americold Logistics. The quarries are home to warehouses and factories and even a USDA inspection facility.
Further north, up around Kansas City, MO, there are several underground storage areas to be found.
The Space Center in nearby Independence, for example, boasts 4.7 million square feet of industrial space, offices and light manufacturing.
But perhaps the biggest and most well-known is Kansas City’s SubTropolis, an industrial park with 5 million square feet of office space, warehousing and even a children’s museum."