In Texas, off of I-45 between Houston and Dallas, there is a small rural town called Buffalo. Some folks built a home underground there, using dome technology from http://www.monolithicdome.com
The direct link to the "Invisible Dome Home", underground, with 3000 square feet of living space is below. They say that people have even parked on top of it - didn't have a clue it was underneath. Interesting the way they made the windowless buried home look cheerful inside with the wall murals. Even out of the ground, these dome homes are hurricane and tornado proof and easy and inexpensive to maintain. They caught my attention. Might want one myself someday.
Hope this was of some interest to you.
The "invisible" dome home...ya can't find the front door...