You don't need to be a caveman or cavewoman to rent a troglodyte house.
There is a big concentration of them near Saumur as illustrated by Troglodytes guide (in French) from Saumur Tourist Office. Some of them were used for mushroom farming.
If you like a bit more comfort with river view, the Maison Troglodyte in La Roque-Gageac (Dordogne) featured on France Bound seems a good pick if you want to slow down.
Looking for warmer climate, head for Andalucia and the town of Guadix near Grenada. A detailed piece about the area on Andalucia.com notes that "ever since the Moorish times, the Andalucians have been fond of living underground because it is the best way of escaping the summer heat waves."
One of the rental options in Guadix is a 'cueva' (Spanish name for troglodytes) Maison "Cueva Amandier" run by French people.
Add a little zest to your vacations.
(* Photo of Maison Troglodyte via France Bound, photo of Cueva by Maison Cueva Amandier...Maison Cueva Amandier site is in French and Spanish only)