1 1. The Sleeper Cave House

Tucked into a 17,000-square-foot hole left by a sandstone mine in Festus, Missouri is the spacious, beautiful home of William "Curt" Sleeper, his wife Deborah and their three kids. The Sleepers almost lost their unique three-bedroom house to foreclosure, but they recently received backing from a private investor after media exposure.

"We feel that our home is eco-friendly," Curt told The Daily Green. He explained that he needs to run no heating or cooling, since the natural insulation of the cave walls keep the inside air 65 to 70 degrees year round. The Sleepers constructed the façade of their dwelling out of 300 sliding glass doors purchased from a local resale shop. "I stripped the aluminum and resold it to the local recycle center," Curt adds. "We pull more than 100 gallons of water per day from the air with our dehumidifiers and then pump that outside to water our gardens and feed chickens."