The city of Latina, 40 miles south-east of Rome, follows the same sort of pattern. Except that its centro storico only dates from 1934: the banality of the suburbs gives way, not to a dense collage of pitched roofs, terra-cotta facades and cobbled streets, but to wide-open formal squares, heroic buildings and avenues, on an axis that leads through the municipal gardens of the Parco Mussolini and comes to rest at the war memorial, a ferociously gaunt sculpture - no weeping women, just a grey stone column surmounted by an eagle - dedicated "To those fallen in all the wars".
All this would come as a surprise to those who wander into the centre, as I did on my first visit, expecting it to echo that of other Italian towns. But this part of southern Lazio is different. It may have a coat of post-war gloss, but underneath it remains the Italy of the Thirties.
The embrace of post-war townscape, redevelopment of its centre and whirling traffic, have lessened the architectural impact of Latina. But when it was created, as Littoria, it must have been remarkable - which was the intention. Before 1932, neither the city nor the surrounding settlements existed. The Pontine Marshes - a coastal strip of about 250 square miles stretching from south of Anzio down towards the resort of Terracina - were almost uninhabited. True, there had been Roman settlements on the coast, and from the Middle Ages the area was used as a winter pasture for cattle brought in by migrant shepherds. But the marshes were also a breeding ground for mosquitoes, and the threat of malaria forced most of the population out for the summer.
As a demonstration of the power of the fascist state, and to increase arable production, the Italian dictator Mussolini initiated a programme in the early Thirties to drain the marshes and eradicate the mosquitoes. It was transformed (by planners who were mounted on horseback for their early visits) from a forested marshland into an efficient agricultural area, with an infrastructure of new roads and towns.
The settlements of Latina (the province shares the same name as its administrative centre) were built between 1932 and 1937, designed by different architects but in a consistent fascist style. The flat concrete surfaces and the firm, sans-serif lettering are coldly Modernist but the forms (particularly the towers and spires) suggest an Expressionist heart beating within. The result rather effectively conveys Italian fascism's attempt to combine the heavy machinery of state with love for - and duty to - God, country and Il Duce.
Of all the settlements, Latina itself, a city of more than 100,000 inhabitants, has suffered the most from subsequent development; and Aprilia, just off the road from Rome to Anzio, is now hardly worth the detour. But Pontinia, built as the agricultural centre for the area, is. Its old market building is worn-out and disused, and the Albergo Pontino on the main square is, sadly, closed. Across the square, however, the town hall is in great shape, still displaying a long quotation from Mussolini running around all four sides of its grand tower. I did a slow lap of the building on my bicycle, to discover, bit by bit, that "It is the plough that marks out the furrow but... the sword which defends it. And the ploughshare and the... blade are both of tempered steel... like the faith in our hearts."
Even more stirring is Pontinia's church. The town is built to a rigorous layout, its streets running diagonally across a square plan, and at the main intersection lies the church, a block-shaped, white building whose only adornment is a fluted rocket that soars upwards -a futuristic invention of the pre-Modernist architectural visionary, Antonio Sant' Elia.
Pontinia is remarkable enough; but eight miles along the coast is Sabaudia, described by Le Corbusier as "a beautiful poem, perhaps a little romantic but full of good taste". The writer Alberto Moravia - who, like the film director Pier Paolo Pasolini, used to holiday in Sabaudia - referred to "a city in rational style which talks to the imagination, not to reason". Moravia's terminology is the PC version of "fascist architecture": the newly erected signs announcing Sabaudia's tourist attraction also refer to: "A model of Italian rational architecture." But no one could describe such heroic structures as Sabaudia's post office, town hall and church - not even its water tower - as merely "`rational". The town's construction was irrationally heroic, too: 6,000 shock troops of Mussolini's public- works organisation, the Opera Nazionale per i Combattenti, laboured for 253 nights and days to complete it, as a showpiece of fascist achievement.
Sabaudia's role in the Latina scheme was as a resort town - which is what it remains. And in most other respects, it remains what it was, too. Although the lack of cars makes it look more like a model town than the real one, the old postcards of Sabaudia, in a marvellous 127-page book published by a local tobacconist, show immediately recognisable sights: the church, with its figurative mosaic (Mussolini appears in a minor role, holding a corn-sheaf) curving back from the vertical to the horizontal above the entrance, to be visible both at a distance and from below; the town-hall clock tower (taller than the one in Latina, which caused a political squabble), with its balcony for calling the populace to arms; the stunning, deep-blue post office, with its imposing staircase to the heavens (well, actually to a small first-floor office); and, most exquisite - curiously so, among all these dramatic buildings - an undeveloped plot, Piazza Roma, little more than a rigorous arrangement of 47 palm trees.
That all this survives almost intact (there are some rough edges) is the consequence of three factors: the lack of a railway station, the protected status of the surrounding area, declared in 1934, and the fact that Sabaudia is not quite a seaside town either in mood (the bright beach paraphernalia outside the shops sits oddly with the austere setting) or geography. The coast, half-a-mile away across a lagoon, offers a good dozen miles of sandy beach backed by dunes and - a miracle in Italy - is almost completely undeveloped. Even the private concessions that are the ruination of most Italian beaches have little impact on such a long strip. Since the town is set back from the sea, Sabaudia's original layout has not been distorted by coastal-strip development; and anyway, the combination of planning controls and inaccessibility (at least in the past, by rail) made development unfeasible and unnecessary.
Enter Sabaudia today from any direction - except the south-east side where it has stretched a little - and you arrive directly at the centro storico. There are no factories, no banal suburbs: just straight to Italy, circa 1934.
Go (0845 6054321) flies from Stansted to Rome's Ciampino airport, conveniently located for Latina on the southern edge of the city, from pounds 90.
Sabaudia has a handful of hotels. I have always stayed at the Hotel Le Palme on Corso Vittorio Emanuele III (tel/fax 00 39 0773 518325), which is quiet and comfortable.Double rooms are from 150,000 lire (pounds 50) in September, 125,000 lire in October
Food is generally plain and cheap in Sabaudia, but Ristorante dal Cin on Largo Giulio Cesare (00 39 0773 55422) is reliably good and costs about 32,000 lire (pounds 12) per head, including wine