A route can be a destination too. And none more so than the sweeping Grande Corniche in the south of France. Stephen Bayley takes a trip along the Côte d'Azur

America has great road movies, but France has the great roads. And the greatest of them all is the Corniche, that incised ledge (the name is related to our word cornice) running east from Nice to Menton on the Italian border.

In fact, the Corniche is not one road, but three. There is the Basse Corniche, the clogged coastal road. With blue seas and glamorous congestion, it is fine if you are not in a hurry. The Moyenne Corniche is a mid-altitude compromise. Actually, if you include the hurly-burly A8 autoroute "Le Provencal" there are four of them, but what everyone means with this evocative word is ... La Grande Corniche.

This is surely the most romantic road in the world, a perfect symbol of French absolutism combined with a French need for access to luxury and frivolity. A masterpiece designed by Paris's L'Ecole des Ponts et Chaussées, the world's first civil engineering school, the Grande Corniche was made to facilitate Napoelon's ambitious Italian campaign of 1796. From an original chemin muletier (mule track), the great engineers made a viable aerial trunk road, audaciously clinging to rocks between sea and sky. But they did not make it quickly. They were still working on it in 1823 when the Countess of Blessington visited. She described a road "boldly designed, and solidly executed, with a disregard of difficulties".

Actually, acrophobes need not worry, at least not overly much. The Grande Corniche rarely rises above 2,000 feet and, while a certain prudence is required, it is more elegant than scary. They always use it in car ads, usually stopping on the section between Nice and Eze with the Alps behind and fine views of the Maures massif and St Tropez in the distant west: with gentle sweeps and Homeric seascape it seems not so much to advertise any particular car, but the primordial, liberating possibilities of motoring itself. Or just the idea of travel.

I have in front of me as I write a photograph taken 80 years ago. It shows an unmetalled stone track with no parapets. There are jutting crags and treacherous slopes. Drops are hidden by friendly-looking umbrella pines, oak, olive and pine. Mules and goats, together with Napoleon's foot soldiers, would be at home here. Now it is smooth, safe and convenient. And surprisingly quiet. Through traffic uses the lofty autoroute, vacationers stick to the coast admiring what Scott Fitzgerald described as "a sea as mysteriously coloured as agate and cornelians ... green as green milk, blue as laundry water, wine dark". Because it was built as an aid to military logistics, the Grande Corniche does not pass many places of interest. The road itself is the great experience. Even from behind the wheel of your airport hire car.

The Corniche is the best entrance to and exit from Nice, the capital of the Cote d'Azur (sentimentally named by an obscure Burgundian poet in reference to his own, beloved, vineyard-covered Cote d'Or). This part of France has always attracted exceptional visitors. Tobias Smollett was among the first of the English. He made his journey to Nice in 1763, before sun-tanned sex in combination with the Mediterranean diet had become basic assumptions of the good life. Smollett said: "Most of the females are pot-bellied; a circumstance owing, I believe, to the great quantity of vegetable trash which they eat". Nietzsche lived in Nice at the Hotel Continental in the rue Verdi. Matisse discovered Nice in 1917. Somerset Maugham, who described neighbouring Monte Carlo as a "sunny place for shady people", kept his Villa Mauresque on the southern tip of Cap Ferrat. Coco Chanel's villa in Roquebrune was called La Pausa because legend claimed Mary Magdalene stopped there after the Crucifixion. Gerald Murphy, responsible for the thrilling motto "Living well is the Best Revenge", lured fashion-conscious Americans, including Scott and Zelda. Typical of the area, Nice's dynastic mayor, Jacques Medicin, was both a convicted criminal and author of a fine cookbook. His ambition was to make Nice into Las Vegas, which he partially achieved.

Back to the road. The most evocative stop between Nice and Menton is La Turbie, the symbolic frontier between Rome and Gaul. Dante visited. Here the Romans repressed the native Ligurians and built a swaggering monument to prove it: La Turbie, La Trophée des Alps is a magnificent colonnade. Looted with consistency and thoroughness, it has now been restored to a state of archaeologically immaculate ruin. The modern village retains a rue du Ghetto, amply eloquent of past conflicts. Here a flirtatious Grace Kelly and Cary Grant stopped in Alfred Hitchcock's 1955 caper, To Catch a Thief. A lifetime later, on 13 September 1982, it was driving on the Moyenne Corniche near La Turbie that a more troubled Princess Grace's Rover P5 left the road. In, as they say, circumstances that have never been fully explained. Except that this glamorous catastrophe conforms in every detail to the danger and romance of this famous road. After all, Napoleon built the Corniche with murderous intent and there are people who doubt the crash was an accident. Rainier, they say, did not fully acknowledge help received in turning Monte Carlo into Las Vegas (this grotesque transformation is a local preoccupation).

If you are lucky enough to make it, the journey from Nice to Menton is not a long one, but you travel as much in time as in altitude and distance. Nice is a modern French metropolis with everything good and bad that that suggests. Menton, in contrast, is old-fashioned and, despite its Mediterranean dress, English. As if to acknowledge this, the Corniche becomes less dramatic as it approaches. In Robert Louis Stevenson's day Menton had an opium den. But after an 1860 article in The Lancet promoted the health-giving climate of what was essentially a fishing village, it was destined for gentility. The category of woman once known as an "aunt" used to inhabit the sleepy hotels. The syphilitic Guy de Maupassant called it a "flowery cemetery". Even Vladimir Nabokov could not help Menton rid itself of respectability. Graham Sutherland, an artist who looked like a dentist, assembled his Coventry Cathedral tapestry in a disused Menton department store.

A road connecting two such different cities is not easily forgotten, especially when travelling it has so many literary memories. We now think of the Côte d'Azur as a pleasure ground, a vanity fair to the frivolous. But Jacques Medicin's Nicois cookbook reminds us that, until the visitors came, it was a wretchedly poor area: among his first recipes is "L'aiga sou" or saltwater soup. But to drive the Corniche is to rise above particulars. It is more about a mood than a journey. The Corniche is not merely the greatest road of the Côte d'Azur, it is the greatest road in France. And when you have driven it and are back in Nice, negotiating your rouget and pichet of local rosé in the bustling Cours Saleya, you think, unavoidably, of all that has passed and remember that Scott Fitzgerald's elegiac "Lost caviare days" said it all.