Aix-en-Provence is one of the loveliest of all French cities, an ancient place of the greatest charm and style, but cool and modern too. It's old, but it's not archaeology: it's a living city.

History, art, sex, food and culture all mingle here in the dappled sunlight beneath ancient plane trees. Julius Caesar was a regular visitor, and Aix was later host to the usual turbulent stream of sadistic, usurious and philandering medieval bishops.

Its architectural character was established in the 18th century: the Cours Mirabeau is the main artery, a splendid, civilised promenade bracketed by fountains, shaded by trees and defined by aristocratic, shuttered classical houses. Full, one imagines, of romantic secrets, past and present, of operatic intensity. Behind them, the Quartier Mazarin. Mirabeau, a politician of the French Revolution, himself married and divorced in Aix, each time in scandalous circumstances.

The Michelin Vert tells us that Aix is the centre of contemporary almond preparation. Maybe, but commercial life has rather passed it by since the growth of Marseilles in the 19th century. In reality, a suburb of the great, sleazy port, Aix maintains an independent, even provincial feel.

Though locked into the busy knot of motorways containing Marseilles, the popular international university of Aix helps it to feel cosmopolitan, not suburban. But it does have a debt to the great city: as Emile Zola remarked well over a century ago, Aix is (very happily) located in the land of bouillabaisse and aioli.

Frédéric Mistral (1830-1914), who founded the Felibrige movement (a renaissance of Provençal culture), studied at the university. The national revival may have been only a partial linguistic and political success, but it was good for the movies.

Marcel Pagnol (1895-1974) moved from being an author of the Manon books to making films about them. They enjoyed international esteem because the Manon movies established a comfortable notion of the rascally, nut-brown Provençal paysan, a cheerful if misleading notion not wholly dispelled by Peter Mayle's book, A Year in Provence.

But Aix has other literary traditions. Zola knew about the odoriferous fish soup and the pungent garlic sauce because he spent his boyhood there. His father was building a canal. Zola pere was an engineer, not a navvy, but the hand-me-down experience was a help in the matter of realism. As the town of Plessans, Aix appears in the first volume of Zola's Rougon-Macquart novel cycle.

Albert Camus spent his last years just outside Aix in Lourmarin. One day in 1960, his publisher, Michel Gallimard, offered him a lift to Paris. Camus was a nervous passenger, and the publisher's widow later reported that Camus kept telling Gallimard to slow down. Not far from Senlis, Gallimard lost control, left the road and hit a tree. Existentially, no other vehicle was involved.

In the Salle des etats in the Hotel de Ville, a wonderfully bad painting of 1902 gives a startling impression of the city's self-image. This is La Provence Aixoise, by a hack called Louis-Gautier.

A magnificent allegorical floozy is firm, plump, pink, naked and supported by nothing other than lavender-hued vapour deliciously swirling. A local landmark, the Mont Sainte-Victoire, is roseate in the background, its peaky profile nicely reflecting her poitrine (breast).

Only in contrast to this high falutin' academic twaddle does the novelty of Paul Cézanne's Bathers make sense. Instead of allegory, structural analysis. Instead of addle-brained idealism, a tough version of realism that was one of the main roads to modern art.

Cézanne is Aix's favourite son, and this year is his centenary, which will be celebrated with a programme of special events. He was born in 1839 and, while he studied in Paris and worked in Pontoise alongside Camille Pissarro, Aix was his spiritual home. Well-off, Cézanne made his studio on the family estate of the Jas de Bouffan.

His art was a steady, thoughtful revolution. Cézanne had a mystical attachment to terroir, what he called ce vieux sol natal (this old native soil). His contemporaries, Monet and Renoir, travelled widely, but he preferred to stay put, working his themes down to the essence.

The Musée Granet in Aix has many other local landscapes by which Cézanne's sober revolution may be judged. His version of La Provence Aixoise, so memorably described by his friend Zola as un coin de la nature vu a travers un temperament (a corner of nature seen through a temperament), has given us a template for seeing the whole of the south of France, with its distinctive light and defined colours. You can almost smell a Cézanne landscape, its heat, its dust and its herbs. The urbane city is a fine contrast to this mystic idyll.

I have been visiting Aix since I was a student and I always head for the Cours and Aix's most famous haunt, Aux Deux Garçons, a grand café with rows of pavement seats. Next door is a fine stationery shop in the high French style. A good newsagent. You live the life, in sunshine.

And leaving Aix, travelling east, you cannot avoid the mountain. Strange how such a piece of geology has become a symbol of this most urbane of cities. It's especially good at sunset.

Cézanne complained late in life that he was having difficulty grasping the edges of things. Maybe, but most of the time he got to the essence. Aix makes you feel that way, too. - Foreign Service