Trails of the unexpected: travellers can now fly direct to Perugia, the Umbrian capital - but because there are no non-stop flights back, you must fly home from Rome. Here is the ideal course between the two cities. By Simon Calder
Half-way across the miraculous Ponte delle Torri, a stern stone viaduct that stomps from the summit of the town of Spoleto across to the Umbrian hills, I paused and gazed down into the sort of valley that puts the V in vast and vertiginous.

And I thought. Of Luton.

Thanks to the new breed of low-cost airlines that are based at the Bedfordshire airport, I mused, it is now much easier to peer down into the deep Tessini river valley.

Here's how. Debonair's new route takes you non-stop from Luton to the Umbrian capital, Perugia. The trouble is, for the return journey you have to go via Rome, 100 miles to the south. Since the airline will charge you the same price whichever city you fly home from, you might as well turn this to your advantage. Buy an "open-jaw" ticket and set a carving course through the heart of Italy.

But first you have to find your way out of Perugia airport. If you think Luton is diminutive, wait until you see where your plane is landing. With a bit of luck, the final approach will be from from the south. The planners have taken advantage of a brief respite in the Umbrian hills to plant a runway on the plain between two miraculous hill-towns - Perugia itself, and Assisi, each clinging to its peak like a wayward sandcastle.

You soon come down to earth. Adamo Giuglietti airport is the size of a shed: a big, bright and recently refurbished shed, but a shed none the less. The arrival of the Luton service has not triggered a bus service, so you may need to rent a car (a good option, considering what's in store) or take a cab. But once along the absurdly grand approach boulevard and through the stout stone gates, which way should you go?

Turn right, and in front of you looms Umbria's capital. Perugia is one of Italy's finest cities - a feast of Renaissance extravagance spilling over a series of hills. It feels a truly three-dimensional place, with a Machiavellian system of stairways and viaducts to help you thread your way under, around and across a city that seems designed for intrigue.

Beyond it, you could subside to the shores of Lake Trasimeno. Yet to adhere properly to the spirit of the open-jaw traveller, you really should turn your back on Perugia and begin the pilgrimage to Rome by heading left from the airport, crossing a tributary of the Tiber, and aiming for Assisi.

Now is the worst and best of times to visit the last resting-place of St Francis. Two years ago, the restless earth rumbled and shook his basilica with hellish force. In the earthquake, four people died when the roof of the upper church caved in. Today, a jumble of scaffolding props up the bruised but beautiful building. You can pick your way through the metallic maze to the simple tomb of St Francis, but, at the moment, the extravagant frescos in the upper church are undergoing painstaking restoration.

While the art of salvage has got under way, an Italian bank has taken over a chapel opposite, and installed a neat exhibition that shows, in the nicest possible way, what you're missing - Giotto's dazzling sequence of 28 frescoes depicting the life of St Francis.

What you may also miss - but not regret - is the normal consignment of tourists. Until the reconstruction is complete (like most projects in Italy, it is promised for "some time in 2000"), many of the tour coaches will bypass the place.

So you can freely clamber up the main street from the basilica to the piazza in relative solitude, enjoying a repertoire of architecture that only Italy can deliver, a meander from Roman to Renaissance and beyond, all of it on a human scale.

Talking of tourists, you probably know dozens of people who have visited the Trevi Fountain in Rome. But how many have been to the town of Trevi, perched on yet another Umbrian hilltop 20 miles south of Assisi? Never mind that the two locations are unconnected except in name; there is nowhere better than Trevi to appreciate the great sweep of the Montimartani that rises in the east from a placid plain - and enjoy the eerie lull of an Italian afternoon.

Buried in the hills further south, Spoleto is another venue whose name is more widely known than you would imagine from its scale. The Festival dei Due Mondi, which begins this week, embraces at least two worlds, sharing Italian zest with the diaspora in America and Australia. Only Italy, though, can boast mouthwatering markets of the kind that you find compressed into the centre of Spoleto.

Pork in all its diversity is a staple in Umbria, whether as porchetta - a whole roast piglet - or pulverised into salsiccia. Before their demise, those pigs prove useful in snuffling out tartufi (truffles) that enliven the pasta here and provide the midday energy boost that you need to explore the many, varied layers of history that sprawl among the hills. The bridge over which I sighed for Luton was built in the 14th century on the course of an earlier Roman aqueduct, and still thrills.

Although at least one road - and a railway - leads directly to Rome from Spoleto, I would urge trying another diversion, to Lake Bracciano. The map shows that the journey south and west comprises more of the same hilly ride, with more contorted contours than an octogenarian's grin. The surface of Umbria and Lazio is a study in geological impermanence: stretched, squeezed and ruptured by volcanoes, one of whose craters has bequeathed a lake that forms a perfect circle.

The lakeside towns of Anguillara, Bracciano and Trevignano are perched at precise 120-degree angles around Lake Bracciano. They are each 12km apart by road. After a trip from point A to point B by way of T, you can confirm that Lake Bracciano is more than merely mathematically elegant. From the town of Anguillara, you can head south for Rome - but, if you are travelling by train, you will need to take a long, dusty road that appears to function as a training track for the capital's scooterati.

At the station, board a spluttery diesel train, as weary as you are. It will amble to the Italian capital in about the time it takes to fly to Luton. At Fiumicino airport, you may lick your lips at the latest addition to Alitalia's fleet: a Boeing 747 dressed up in electrifying blue, a massive flying advertisement for Baci - which means kiss. It is promoting the chocolate-covered hazelnuts that are made in Perugia, and are also available in Luton.

Travellers Guide

Getting there: Debonair (0541 500 300) flies three times a week between Luton and Perugia. Return flights go via Rome. The lowest fare is pounds 154, whether you return from Perugia or Rome.

I rented a car for the trip from Avis, as part of a cheap, last-minute package from Simply Tuscany & Umbria (0181-995 8277).

If you don't mind taking the odd longish cab ride, you can make the trip much less stressfully by public transport; trains and buses are cheap and fairly frequent.

Maps: Two Touring Club Italiano maps proved to be the most practical: those for Umbria Marche and Lazio.

Information: For full details about the Festival dei Due Mondi, contact the Teatro Nuovo in Spoleto (00 39 0743 44097 or 40356).

The Italian State Tourist Office is at 1 Princes Street, London W1R 8AY, (0171-408 1254); (brochure request line on 0891 600280).