MODERN-DAY FLINTSTONES

In western France, cave dwellers burrowed into the hills centuries ago. Their homes are now sought-after properties. 'It's like living outdoors. Your home is part of the hill, and it all seems natural; you feel very close to the earth'

STANDING among the chickens and chimney stacks on Bernard Foyer's grass roof, I peered down a ventilation shaft into his mole-hole farmhouse and learned a thing or two about living, as he put it, "inside the rock". Good air flow is essential, he said, as water penetration and humidity can cause constant maintenance problems for cave dwellers. Do-it-yourself cave improvement seems fairly straightforward, however. All you do is chisel holes in rock faces.

A small, shallow recess serves as a shelf; scoop out a much larger hollow and you have a one-bedroom extension. More creative troglodytes might tackle steps and stone sinks, fireplaces and carved friezes. But there is no need to hang wallpaper. Limestone has the look of rough-set Artex and, as Bernard Foyer's less than well-ventilated space demonstrates, fine layers of velvety green lichen and swirls of black mould texture the walls of their own accord.

Monsieur Foyer is a New Age "troglodyte" (in French, the word describes both dweller and dwelling). He lives a few miles from Doue-la-Fontaine, among a sea of Loire Valley sunflower fields, in a restored 19th-century rock-cut farmhouse called La Fosse. When he and his family (including rabbits, ferrets, cats, dogs and sheep) moved underground in the 1970s, the farm had been left empty for 50 years. Hundreds of other similar dwellings in the region were either derelict or had been destroyed; many have now been taken over as wine caves. Foyer became concerned that France, which has the largest concentration of domestic caves in Europe, was in danger of losing a part of its social history. By opening his troglodyte home to the public, he set out to show that this was a legacy worth saving.

The rock-cut homes of western France are man-made. Cut from rich seams of tufaceous limestone (tufa) they are scattered across a vast area, along the Loire Valley and those of its main tributaries, the Loir and the Indre. Tufa, to get technical, is a sedimentation of calcareous silt about 90 million years old. It is fine-grained, permeable, rich in silica, easy to cut and the colour of dairy cream. A gem among building stones, it has been mined since the Middle Ages.

While the rich built abbeys, chateaux and fine "maisons tufa", local artisans mined the material, sold it and moved into the caverns left by excavations. The move underground started in the 11th and 12th centuries and was still flourishing in the 18th. These homes were custom-built, with distinctive architectural idioms. Facades were created by building a wall of hewn stone across the cave's arched entrance; circular lights were set above front doors; religious statues perched in alcoves.

Up until the late 19th century, a substantial part of the population of Anjou's Loire Valley region lived in troglodyte villages - either carved into river valley cliffs or (like Bernard Foyer's) into the vertical edges of quarries, which form craters in the open farmland. Some die-hard French cave dwellers see no reason to leave. Why should they? They may be a little damp, but tufa troglodytes are versatile, well insulated, back-to- nature houses with cute little windows cut into sheer rock faces and womb-like, vaulted rooms - and they are beginning to enjoy a renaissance.

Visiting troglodytes is a big tourist pursuit in western France; if you include wine and mushroom caves, the region sustains around 600 miles of underground life. Restoring dilapidated "maisons troglodytes" is also becoming popular; it may soon be to western France what gentrifying farm workers' cottages was to the West Country in the 1970s. Some areas of the Loire, like the riverside villages around Saumur and Tours, are seeing the first signs of redevelopment. And there, a new phenomenon is emerging - the cave as holiday home.

The most developed community of nouveau cave dwellers is at Troo, a picturesque troglo-village cut from an outcrop of tufa which rises sharply from the Loire Valley plains, north of Tours. Between the 17th century Chateau de la Voute at the bottom and the tower of La Collegiale Saint-Martin at the top, the south-facing hillside is a labyrinth of man-made caverns and galleries, dug as medieval hill forts, extended by centuries of tufa mining and adapted as houses.

Troo's higgledy-piggledy terraces of rock-cut houses are connected by narrow cliff paths and steps, treacherous at night (unless you have a torch) and vulnerable to the occasional landslip. Hand-written signs point tourists in the direction of "les maisons troglodytes" and, in the summers, thousands of visitors toil up and down the hillside, betwixt chateau and church, peering over hedges at the inhabitants of this curious village.

Protected by "Direction Patrimoine" classification (the French equivalent of an English Heritage conservation area), Troo is a model of troglodyte architecture, but none of the houses is open to the public; many are hidden behind thick shrubbery; some are just difficult to find. There is a breathtaking view of the Loir from the hill's summit, but the only real troglodyte attraction is Troo's cave museum and archive.

Here, faded sepia photographs of 19th-century troglodytes show that these were once poor, working-class homes - warmed and furnished but primitive and overcrowded. A few empty, neglected dwellings are still redolent of their humble origins, with rusted iron kitchen ranges, dirt floors and raw crags of limestone wall which become increasingly organic when left untreated. Today, most of the troglo-cottages have been colonised by artists, academics, foreigners and city weekenders. A tiny bit twee, Troo is a little bastion of bourgeois Bohemia, a trend that may spread to other corners of the French troglo-world.

British food writer Sophie Grigson has a holiday cave in Troo. Wealthy Paris art dealer Jean Laurent spends his weekends there, in the subterranean splendour of an expensively converted cave. Sharply contemporary, bordering on the high-tech, his rock walls have been shaped into perfect arches with the uniform texture of pebbledash. He was not at home when I called so, like many a frustrated tourist, I saw only the glint of stainless steel behind venetian blinds.

French Moroccan lawyer Laila Renard lives at the top of the hill, in a labyrinth of vaulted chambers set deep into a cliff. Her arched rooms are connected by rock-hewn passages and lit by tall windows; her bath is built into a limestone shelf. Her bedroom, a windowless womb of rough, unpainted rock, once housed goats.

Artist and antiques dealer Jean-Marie Garnier and his dentist wife Pascalle have made a permanent home in Troo. Like the facades of many troglodyte dwellings, theirs is a blend of constructed stonework and bulging natural rock draped with honeysuckle, ivy and wild valerian. A circular chimney rises from above a geranium-decked wooden balcony and the Garnier garden is a picture. It is probably one of the most photographed tourist sights in Troo.

Step into the hillside and the most impressive example of Troo's troglodyte architecture is the interior of the cave complex belonging to fine art academics Jean-Paul and Sabine Lallemand. After a long spell in Africa's Ivory Coast, they developed Jean-Paul's grandparental cave into a home. Gradually, they spread into neighbouring caves to create a separate den for their student son, a small flat on an upper level and a two-bedroom "troglo-gite" for paying guests.

In each space the asymmetrical curves of the walls have been left rough and rocky. Painted with a lime-based wash, a shade whiter than tufa, they are textured with pick marks and chiselled grooves. The irregularity of the surfaces allows for tricks that wouldn't pass muster in a conventional home. You don't have to bury wires or pipes, but simply conceal them behind lumps of plaster; false partitions can be built of clay, concrete or papier mache and made to look like limestone. You can slide furniture into tailor- made alcoves, and set lights into recesses. Cave renovation is an art, a form of sculpture. Imagination can run wild, but there are also practicalities to consider.

Retired engineer Bernard Savaette, who has moved from Paris to Troo with his American partner Barbara, is renovating his old family cave. The problems and rewards are typical of most troggy projects. Hacking a staircase or a doorway out of six feet of rock may cause headaches, but damp, says Barbara, is their number one enemy. In a deep, poorly ventilated cave like theirs, a dehumidifying system is essential.

London-based English teacher, Hedy, paid pounds 35,000 for the habitable but unmodernised Troo troglo-cottage she bought with her late husband three years ago. "It was splendid at one time," she says, pointing out that the magnificent limestone fireplace is thought to date from the 11th century. At its inner limits, the house recedes into dark wine caves furnished with museum pieces.

Hedy has put in heating and wiring, but says the environment made the work more expensive than in a normal house. Short visits leave her little time for prettifying her vast grotto-like holiday home. While she lives in the smaller of two chambers, the walls of the principal cave have shed fine white dust on the furniture and sprouted various species of fungi.

"It's like living outdoors," says Hedy. "Your home is part of the hill, and living here feels natural; you feel very close to the earth." You also wake up in the night to a pitch-black cave, and find yourself fumbling desperately among prehistoric sediment for a rock-set light switch. !

FRANCOPHILES with troglodyte tendencies will need patience and determination to find the cave of their dreams. Perhaps it was my rusty O-level French, but the Loire Valley estate agents I spoke to seemed bemused by my requests for details. None came up with the goods.

Rock-cut properties do come up for sale, however, but information comes by word of mouth. Ask in cave-dwelling circles; they all seem to know each other. If you do see an agent's board at the mouth of a cave, take down the reference as well as the telephone number.

The best areas to look are the Loire Valley villages between Angers and Tours; south of the Loire between Saumur and Montsoreau; and on the north bank between St Michel-sur-Loire and Vouvray. Also try around Chinon on the river Vienne, and Loches on the Indre. Or go north to the Vendome area of the Loir (Montoire, Troo, Les Roches).

Troglodyte houses sell for between pounds 10,000 (for a rough-hewn, unmodernised hole) and pounds 60,000 (for a ready-converted cave with home comforts and services); pounds 30,000 will buy a cave with potential, and you can dig an extension without planning permission. Pure rock-cut dwellings are rare; most have an element of brick, stone or timber. Many are hybrids - half house, half cave - in which the front section looks like a house emerging from a rock escarpment. In cave-rich areas, conventional homes have rock-cut outhouses and garages.

One semi-troglodyte house in Troo is for sale. Though cheap (pounds 11,000), it requires extensive renovation. The property consists of a crumbling cottage (one up, one down) grafted on to a vast untreated grotto - dark, dank, eerie and big enough to house a double-decker bus. The original family lived in the two rooms and used the cave for storage or shelter for animals. With little scope for light or ventilation, it's a difficult space to convert, but would make a brilliant party venue. The agent, Aubrun Thimel is based in Montoire (00 33 5485 0552).

To get a feel for troglodyte living, visit La Fosse, near Doue-la-Fontaine (Bernard Foyer's 19th-century troglo-farm: see text) or the Louresse- Rochemenier commune (an 18th-century rock-cut village, now a museum). To explore the potential of rock-cut construction as contemporary art, visit sculptor Jacques Warminski's "L'Helice Terristre" at L'Orbiere, near Saumur. This is an extraordinary walk-in sculpture which penetrates the rock with a series of carved tufa cavities and tunnels, visceral in texture. A convex exterior work looks like the guts of the earth splurging out on to the surface. Work is still in progress.

If you want to stay in a cave, the Lallemand family in Troo (see text) offers a splendidly furnished two-bedroom "troglo-gite" for short holiday lets (00 33 5472 5787). In Vouvray, Les Hautes Roches hotel (00 33 4752 8888) offers the last word in rock-cut luxury with six troglo-bedrooms overlooking the Loire. Gites de France (0171-629 5035) has a limited selection of troglo-cottages in its brochure, and Brittany Ferries (0171-836 5885) also has a couple of semi-troglogites in its brochure.