Underground homes are increasingly the way to go when land prices rise beyond the insane.
The simplest troglodyte-dwelling is a cave- and people still live in such houses along the Loire river and other parts of France. These houses often have a normal frontage with windows and the cave extends over several floors and not so far back as to tunnel into cold damp rock- though of course some take advantage of the limitless possibilities of expansion.
My own experience of cave living is sleeping in paleolithic caves both in the UK and in the Sahara. Typically those caves have big wide openings and perhaps tunnels going back into larger areas behind. The open area is under a convenient overhang so you never get wet. You can live very comfortably in such a cave and use the dark tunnels for storage or maybe for religious or artistic purposes.
A house is really just a freestanding cave, and we are, more or less, simply cavemen with mortgages. However if you return to the trog lifestyle you can be a caveman without a mortgage.