I bet you obeyed all those sings along the way that said “Clean Restroom” too. 
HGTV’s What’s with that house has featured
A “cave” dynamited into the side of a mountain
And it must have been a different show, but I think saw another one where the house was built into a mountain that is/was used for skiing.
I didn’t read the whole website; I just remember seeing it profiled on TV. I’d imagine if you decide to move into a missile silo you carefully consider your needs.
The opal miners in White Cliffs, NSW, Australia lived in the caves produced through their mining. I had the fortune of staying in one. I’m not sure how much mining is still done, but people still reside in the caves.
Oh there’s a huuuuuuuuge restroom between Phoenix and Moab. I stopped and used it 2 or 3 times :D.
Yeah. Not to mention the truly ancient Deep Crow in Power Dome A.
Let’s put it this way. Don’t go into Power Dome A.
Back around 1880, some wacky doctor was convinced that cave air was a cure for tuberculosis-so he constructed cabins deep inside mammoth Cave 9in Kentucky). anybody know if these still exist?
“In a hole in the ground there lived a hobbit. Not a nasty, dirty, wet hole, filled with the ends of worms and an oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it was a hobbit-hole, and that means comfort.”
I managed to stumble across a website by someone whose dream is to build and live in a hobbit hole.
I just remembered the Ohio Pyramid House, in Hamilton!, OH, which is underground, too. I found a link referencing it and a lot of other interesting homes:
http://www.jiancai365.cn/decorating/Unusual-Architecture-From-Around-the-World.htm
[slight hijack]About half way down the page, there’s a picture of a “Thin House” in London. Wouldn’t that be like living in your childhood ant farm? :)[carry on]
Awesome!
Thanks for all the links everyone, I’m now going to kick back and read all the posts.
Gus
Check out post #9 (I was about to post the very same thing). 
I saw Hole 'n the Rock when I was a kid and if memory serves, it’s worth the stop.
Oops. Yep–once I actually bother to read the posts instead of searching the thread for “Hole in” – there’s the link. What I remember most about the the tour is the young guide, not quite comfortable with his spiel, and Harry the stuffed donkey. A classic American roadside attraction!