A troglodytic dwelling was very good value : lower building costs, less work involved, and little maintenance.

Jonas is secluded enough to fit the needs of monks. Also, this place is neither strange nor unique in the area, since there is another troglodytic site near Perrier, where the valley changes into plains. This second site is dug in a tuff-stone cliff facing South.

Local lords would decide whether such monasteries could be built and maintained. Many disappeared, and this is what happened to Jonas.

In the XIth century, those knights who used to live in the lord's castle moved to the estates they owned and had many manors built.

Jonas : in the beginning, the dwelling itself was dug into the cliff. It was only comprised of a few rooms (section A of sketch). Later, a half-dug, half-built section was added, with the typical feudal symbol : a prominent tower (section B).

During the course of the XVIIth century, the place is deserted. The landlords live elsewhere and only the chapel will be used until the Revolution. Some rooms are then used to breed pigeons.