The question intrigued me enough to send me off to Apulia, that long, slim province of southern Italy on the Adriatic. The Gargano is the spur of Italy's boot, long considered by the Italians a remote land of mystics, saints and pilgrims - and perhaps a trifle too serious.
As I drove over the Tavoliere, the great chequer-board plain of northern Apulia, I tried to imagine the scenes at the end of the first millennium as pilgrims from as far away as Canterbury and Compostela followed the Via Sacra from Rome, crossing this scorching plain in their thousands. In their midst, reputedly walking barefoot from Rome to atone for the sin of murder, was their temporal ruler, the Holy Roman Emperor Otto III, a baby-faced 19-year-old German megalomaniac.
Urged on by his tutor, Gerbert of Aurillac, he had attempted to revive the glories of ancient Rome by moving the capital back to the Eternal City and re-establishing the Senate. Gerbert himself, a man of great erudition, had gone on to become Pope Sylvester II.
However, the new Pope's passion for Arab scientific discoveries alarmed the pious so much that they believed an Antichrist sat on the throne of St Peter - and that therefore the prophecies were about to be fulfilled and the world would end with the millennium.
Amid the confusion and fear, in the dying months of the old millennium, a pilgrimage of faith began to descend down the Via Sacra to the Gargano, a white limestone promontory seamed with grottoes. It was towards one of these that Otto and the other pilgrims came struggling. In particular they would be seeking out a single footprint left in dark stone ...
The footprint takes us still further back in time. In AD490, a farmer searching for his prize bull had found it in a deep grotto above the peninsula's western cliffs. Failing to entice it out he had shot at it - only to have the arrow turn in mid-flight and wound him.
An excited Bishop of Siponto proclaimed a badly needed miracle, when he saw a vision of St Michael clad in shining armour in the dank recesses. The archangel's footprint left in the stone quickly became the focus of veneration and plenary indulgences, and Monte San Angelo, as it is now called, has, to this day, remained one of the most important shrines in Christendom.
I myself staggered in from under the noonday sun to my first stop on the Via Sacra, the lovely 6th-century monastery of S Marco in Lamis. There I found a Father Marius, planning a pilgrimage of his parishioners to the Holy Land.
"Did Otto really walk here all the way from Rome in his bare feet?" I asked. "It is legend," laughed the Capuchin friar. "He would have been on horseback, and he and his nobles would have been put up very comfortably here in our cells. But records show that humbler pilgrims did go barefoot, and slept on straw in the corridors."
I put all my small lire notes into the offertory box and received the traditional pilgrim's benediction of a cross drawn on my forehead with holy oil. My instinctive withdrawal provoked mirth: "Don't worry," said Father Marius. "It's only a little cross."
As I toiled up the last few precipitous metres of the Via Sacra, the orderly rows of white limestone back-to-backs which formed the medieval town of Monte San Angelo gave way to an Angevin bell-tower and a very winding pathway scored with carved handprints and footprints left by medieval pilgrims.
I ducked out of the sunlight and descended a stone staircase to reach the grotto itself. This sweet-smelling cavern was murmurous with the rhythms of the Mass as the faithful crowded around the altar, adorned with a boyish statue of St Michael, and a sixth-century bishop's throne, which allegedly covers the sacred footprint.
For a small fee you can visit the crypt, entered through dark bronze doors, with beautifully incised Biblical scenes in silver. Its vaulted limestone passageway was the entrance Otto would have used. Its columns carved in flowing tendrils of leaves and flowers are light-filled now but a millennium ago, torches would have transformed the rough stone vaults into unimagined phantoms. I envisioned Otto, divested of his triangular crown and purple boots, crawling down the crooked twisting "steps of the sinners" in agonies of self-doubt and recrimination. For not only was he trying to deflect divine wrath from his people, but also from himself. Having expiated his sins, he would have been allowed to climb the straight staircase to the outer world.
I hope he was allowed to. But while reflecting on this pilgrimage, I recalled something else. Namely that 1,000 years later, the small promontory of Gargano has become the source of an even greater religious phenomenon: that of Padre Pio.
This May, two million of his followers crowded into Rome to hear Pope John Paul bestow beatification on the Padre, the man whom Vatican officials once dismissed as "a holy fraud". At San Giovanni Rotondo, a huge portrait of the father, picked out in lights, dominates the village and face of the basilica which now envelops the tiny church to which the frail young monk came in 1918 and where he was marked with the stigmata - symbol, as he said, of "the agony of not loving Christ enough".
The reverence generated among ordinary people by Padre Pio - who died in 1968 aged 82 - is palpable; the fruit of their gifts, the best- equipped hospital in southern Italy, rises next to the basilica. On the other side, the new church is taking shape, in the form of a pilgrim's shell badge. Designed by Renzo Piano, of Pompidou Centre fame, it will seat 7,500 and the vast nave will accommodate thousands more standing.
I joined pilgrims filing down into the crypt to pray at his tomb, which was covered with lire notes and flowers. Shuffling through the original mission, with its niches containing various sacred relics of Pio, we arrived at his cell, maintained exactly as he left it, with his outsized sandals (because of the stigmata) beside the white-counterpained bed. The Hail Marys crescendoed and a woman in a wheelchair touched the doorknob reverently while another dialled the recorded voice of the father and conducted an apparently two-way conversation with him.
What could I think? As I drove from San Giovanni Rotondo, the ripening wheat fields with slashes of poppies began to resemble the stigmata. It was time to plunge through the cool canopy of beeches and pines of the Umbra forest, and down to the shimmering coast.
Vieste thrusts out into the clear waters of the Adriatic like the prow of a great ship. Founded by the ancient Greeks in the 10th century BC, and sacked by the pirate Dragut, its historic centre preserves the atmosphere of a Cycladic island, with its labyrinthine white alleys, steep cobbled streets and glimpses of the sea through shaded medieval arches.
In the mild evening light, the sound of animated conversation drifts from the bars tucked into the little piazzas around the headland. I found another grotto - this time a fish restaurant offering a great bowl of zuppa di pesce, all of the fruits of the sea washed down by a fine Apulian wine. This set me up for a sail around the coast next morning.
The deep, cool fissures seem to offer a siren call (although the "mermen", the sea lions, left it to the skin divers 20 years ago). The boatman cuts the engine and you drift into a huge, domed cavern, with fish sending off trails of phosphorescence under the keel, or into the magical magenta and gold striation of the Tavalozza (picture-frame) cavern.
We sailed down the coast in and out of grottoes for two hours while my companions, pilgrims from Lake Como, sang Neapolitan songs to an accordion. I could hardly wait to dip into this vivid aquarium.
Later I took the aliscafo (hydrofoil) to Italy's first marine national park, around the Tremiti islets, 30 miles out in the Adriatic. It left me at tiny St Nicola, with its precipitous climb to a castle and a numinous Cistercian abbey with an 11th-century mosaic floor and a superb crucifix saved from a Byzantine shipwreck.
I took the ferry over to St Domino for lunch amid the pines, and then cooled off in a minuscule cove of white sand and transparent turquoise water. A boat can stop over the 9ft-high bronze statue of Padre Pio, glimmering in the depths. Even here the spirits of the past are ever present.
ITALY TOP TO TOE
Italiatour (tel: 01883-621900) offers three-night breaks at the three- star New York Hotel and the four-star Galles Hotel in the centre of Milan from pounds 299 and pounds 360 per person respectively, based on two people sharing and including return flights and breakfast.
Go! (tel: 0845 60 54321; net: www.Go-fly.com), British Airways' low-price air operator, flies to Milan from Stansted three or four times a day from pounds 90 return if your stay includes a Saturday night.
Go! (see above) flies three times daily to Rome from Stansted from pounds 90 return, if your stay includes a Saturday night.
John Crossland took the air-conditioned train from Rome to Foggia (tickets cost about L50,000 or pounds 17) which runs every couple of hours and takes about three hours. He picked up a new Punto Corsa air-conditioned car, booked through Italian specialists TransHire, Unit 16, 88 Clapham Park Road, London SW4 7BX (tel: 0171-978 1922).
Hotel facilities in the Gargano generally have some way to go to reach international standards, and in the height of summer it is imperative to check that rooms are air-conditioned. One first-class hotel which is showing the way, with fine cuisine and friendly staff, is the Hotel degli Aranci, Piazza S Maria delle Grazie, 10 Vieste (tel: 0039 0884 708557).
Contact the Italian State Tourist Office, 1 Princes Street, London W1R 8AY (tel: 0171-408 1254; brochures 0891 600280).