LOIR VALLEY, FRANCE — I’m in Fred Flintstone territory, but with a Gallic twist. The steep hillside behind is full of ‘upmarket’ cavities arranged neatly in tiers, and with plenty of people happily living inside.

These cave homes, or troglodytes, are man-made and carved out of tufaceous limestone, or “tufa” if you’re a local.

The troglodytes, or “trogs” (which refers to both the caves themselves and those who dwell in them) are dotted all over this region, but Troo is where they have best been preserved.

“This town does not have streets of elegant houses like other areas: the local people live in cave dwellings, cut into the tufa at different levels.” Or so writes the enlightened author of an 1860 guidebook.

He continues: “The picture presented by these half-wild retreats is quaint: It is easy to imagine being transported into the middle of the forest, to places where barbarians live.”

Today, those same “half-wild retreats” have satellite dishes hanging off the walls and silk curtains suspended from fancy timber windows.

The tufa has been around for a quite while — about 90 million years. As far back as the 12th century, Troo had nearly 4,500 locals, most of whom lived in the caves. But these days, who would want to leave a world soaked in sunlight to restore a trog dwelling?

Plenty of folks around here, it seems.

The world of the trogs in Troo has become a highly coveted one, attracting a set of bohemian outsiders keen to burrow farther into the hill.

Roll-up artists and artisans, weekenders from the cities, foreigners looking for fun, and generally anyone with a bit of cash and a penchant for quirky.

After all, why have a plain, old holiday home when you can buy a novel cubbyhole instead?

Lots of the trogs are used as wine caves, but the ones that have been restored as homes are replete with modern luxuries. If you can accept the the areas that are minus any sun, you won’t get much closer to nature than staying in one of these.

Rooms inside are arched and chamberlike, with electrical lighting set into recesses, and plumbing and pipes well hidden behind a couple of light layers of plaster.

But this is the best I’ve heard yet — you can dig an extension without applying for planning permission.

Of course, most of them now have some elements of brick or stone in the construction, making them more half-house, half-cave.

Seems like semi-trog is the best way to go.

In previous centuries, these dwellings were mostly shelter for the poorer sections of society, but have become more fashionable. France supposedly has the largest number of domestic cave dwellers in Europe and their trogs aren’t unlike some of the cuevas in Granada’s Sacromonte in Southern Spain, originally inhabited by the Spanish gitano (gypsy) population.

Coming from the word “trou”, meaning “hole”, Troo is one of the smaller villages scattered along the Loir River between towns like Vendome, La Fleche and Le Lude in the Loir Valley.

The valley is south of Paris, north of Bordeaux and just above its more famous cousin, La Loire Valley.

You could easily drive through the village and out the other side without realizing there is a whole cosmos thriving in the cliffs behind the main stretch of road.

Most of the restored trogs are private homes, but some are open to paying guests. The “troglo gates” have turned out to be a strong tourist attraction, and it can be pretty hard to get a booking in high season.

As much as I love the idea of getting closer to the earth’s core, I also have a big fascination with full-on luxury, and when it involves Louis Quinze furniture I get completely carried away.

Lucky then, that I know that there’s another extreme when it comes to accommodation in this village.

Clambering down the steps of a treacherous pathway hewn into the cliff, a pair of wrought-iron gates leads up a steep driveway to the impressive Chateau de la Voute. The rolling terrace in front looks out over the Loir; the pretty hamlet of Saintes Jacques des Guerets lies beyond.

I get the “chambre Balzac”, with its lavish blue velvet covered furniture, period French fabric and canopy-draped bed. The tall windows frame a view onto lush green gardens surrounding the chateau.

Sneaking a glance into the Napoleon Suite down the corridor, I see a maid struggling with a distinctly non-vintage vacuum cleaner. Ivory-coloured wallpaper is embossed with gold, the matching drapes shading a plush red bedspread over an old mahogany bed. This room looks at least as chic as mine.

Cave or castle? Think I’m happy in the latter.