No autoroutes run through the Ardèche; nor do any railway lines. Even traffic lights come as a surprise. In fact, I cannot remember ever having seen any. This département is surprisingly small; Privas, the capital, has a mere 10,000 inhabitants. Yet, the Ardèche splits into two distinct parts. The southern half has a Mediterranean feel, its sun-baked fields dotted with olive trees or striped with lavender bushes whose purple flowers perfume the air in June. Signs advertise Camping les Lavandes; market stands are piled high with eau de lavande, miel de lavande and savon de lavande (lavender water, honey and soap).

The northern half of the département is greener, with forests of chestnut trees producing marrons and châtaignes. The single kernel nuts provide the region's world famous marrons glacés, an excellent souvenir of Privas or Aubenas. Chestnuts with several kernels are used for purée and a liqueur de châtaigne. Add it to white wine to make the Kir-like Castagnou. On a topographical map, this landscape is like crumpled-up brown paper. Stand on the ramparts of one hilltop village and its neighbour seems almost within touching distance. Try driving there, and you plunge into deep valleys, zigzagging uphill and down dale. No wonder locals never give distances in kilometres, always in time.

These villages are all very medieval, all built of stone that turns golden in the sun. Ruoms still boasts seven towers; Rosières is named for the rose bushes once grown for their essential oils. Explore Joyeuse and its museum all about chestnuts and chestnut wood; drop by the Saturday morning market in Les Vans; visit the museum of rural traditions in St Alban Auriolles. The tourist board suggests routes that link the important sites, but it's just as much fun to drift off along side roads, losing yourself in the folds of this rugged landscape.

Over the centuries, the Ardèche has rarely starred in French history. When it did, the result was painful. Having converted early to Protestantism during the Reformation, the region was brutally suppressed by Royalist troops in the early 17th century. At Pranles, half an hour from Privas (itself burnt to the ground in 1629), Le Bouschet was the Durand family farmhouse. These Huguenot martyrs are remembered in a small but moving museum, with French-language bibles printed in the Netherlands and smuggled into the region, as well as copies of baptisms written in Greek for secrecy. The massive stone walls provided priest holes, hiding places for the illegal Protestant clergy.

In the hamlet of St Pierreville is Ardelaine, an enterprising living museum. We dubbed it, 'a thousand things to do with sheep' and it covers everything from wool and weaving to meat and milk. Did you know that it takes two to four fleeces to make one sweater? In the pens, examples of ancient breeds from all over Europe include crumple horned Jacobs and black-faced Scottish sheep.

Even if you are hurtling down the A7/E15 autoroute past the Ardèche, do spend an hour or so in Viviers, where the château and the cathedral are piled up onto a crag overlooking the Rhône Valley. Stroll up the cobbled streets and down alleyways barely wide enough for two. Or venture deep inland to Antraigues and dine at a small restaurant on the main square, where locals play pétanque under the trees.

The local produce is rustic, with full, honest flavours. What could be nicer than a platter of local raspberries, wild bilberries and peaches with a tray of Picodon goat's cheese or the soft blue Coucouron cow's milk cheese? Order a glass of the composer Wagner's favourite fizz, the sparkling Saint Péray; sip a chilled Condrieu, made from the Viognier grape. Take time over a bottle of a powerful Rhône red from Cornas or Saint Joseph to wash down the pâté-like caillette or estouffade de sanglier, a wild boar stew.

Tradition is everything in this part of the world. Although no SNCF trains run through the Ardèche, the Mastrou, a lovingly restored steam engine puffs its way up the Doux Valley from Tournon in summer. We departed at 10 am, and arrived at noon in the village of Lamastre, a favourite spot for cookery writer Elizabeth David over 50 years ago. Little has changed.

While I spend time poking about villages, active types cycle, hike, fish, ride, canoe or climb rocks. The biggest rock of all is the curious 1,551m-high granite heap, the Gerbier de Jonc. Here, in the far west of the Ardèche, is the source of the mighty Loire River. And if you want to see Nigel and Nippi's house, it's in Les Fabres, just outside Vernon, near Joyeuse. All you need is a magnifying glass to find it on the map.