Caveland, Festus, Mo.
Fred and Wilma Flintstone, meet the Jetsons. First a sandstone mine and later a roller rink and concert venue where Bob Segar and Ike and Tina Turner performed, the nearly three-acre property known as "Caveland" was purchased on eBay in 2003. Its new owners, according to their website, transformed the cave into a naturally insulated two-story, three-bedroom home with a gently curving staircase, hardwood floors and 28 salvaged sliding glass doors on the facade. Most of the rock walls are still exposed in their natural state. Once licensed as a bomb shelter, the cave has a natural spring and city water.