A 1977 Underground Cave House Covered in River Rock

Built in 1977 by Andy "Caveman" Davis to fight rising energy costs, this earth-sheltered house in Armington, Illinois goes all the way in: an undulating concrete exterior, a bermed roofline, and interior ceilings and arches covered in river rock. Reddit's first reaction was hope for a hobbit house. Its second was a long conversation about dust.

A Cave With a Plan

The house offers over 2,300 square feet of underground living space, engineered for natural climate control long before eco-building became a trend. The river rock that lines the arched corridors was hand-collected by the Davis family on annual trips to Colorado. Today it's a massive blank slate: the structure is in place to finish a 5-bedroom layout with 3 baths, and there are already two separate electric meters, which makes a duplex conversion easier to imagine. The listing pitches it as a single-family cave house, an income-producing Airbnb, or a multi-unit property, and the sale includes two brand-new, uninstalled argon gas circular windows, valued at $15,000, for whoever replaces the old ones.

Know What You're Signing Up For

This is a finish-it-yourself project, and the photos suggest a long road. An electrician in the Reddit thread pointed to exposed extension cords, drop lights, and questionable receptacles, and said the walls would need to be properly built out before the wiring could be done right. Other commenters saw signs of past water and what looked like faint mold near the floor drains, and one who has lived in an underground house said upkeep is a constant job. That's commenter speculation from photos, not confirmed conditions, so a thorough inspection would be the first order of business.

The Internet Has Thoughts

Naturally, this listing caught the attention of Reddit's r/zillowgonewild community, where the first pictures raised hopes of an eccentric exterior hiding a cool interior, and then the interior turned out to be, in one commenter's words, a cave. People compared the candlelit feel to a famous opera phantom's lair, then immediately worried about dusting every pebble, joked about hanging rhinestones and a waterfall in the living room, and said the bumpy stone surfaces were setting off phobias. One commenter sarcastically applauded the architect for resisting the modern trend of homes that feel inviting. See what people are saying about it here.

Think you know what a 1977 underground cave house costs? Take the price quiz and find out. View the full listing here.