Seymour Cray, the world’s best supercomputer designer for a third of a century, worked on digging a tunnel under his home at times when he was stuck on a design issue. He said that elves came to him in the tunnel and whispered solutions to his problem.
Of course, he knew that there really was a Soviet nuclear missile targeted at his home.
I’ve long had this dream, too. I’d go with a handmade-looking shack on the edge of a cliff, so my lower levels could have a view.
My artsy aunt did this back in the 60s… had what looked like a small house in a thick woods, but it was really just an entrance foyer with a circular stairway going down to three huge levels dug into the side of a ravine.