The prayerful continue to come to Glencolmcille, a broad glen on the south-western extremity of Co Donegal, to honour St Colmcille. Such is the ever-increasing drama and beauty of the coastline approach from Killybegs towards the village, even the most sceptical of travellers would find it difficult to shrug off a spiritual frisson. The power of folklore and tradition, as much as religious faith, sustains the saint's association with this place. And this week archaeology has added an extra dimension to the pursuit of sanctity. All summer long, Oideas Gael has hosted Irish-language courses as well as other activities such as hill-walking and pottery.

Far from a mere tourist resort, this corner of Donegal is making a cultural statement: even non-native visitors appear to be speaking Irish. And as Donegal Irish offers the first language at its most lyrical and seductive, it is surprisingly easy to begin using it. Student archaeologists are caught between the wealth of archaeological riches on view and the competing music and linguistic distractions. "And how would you explain this monument?" asks archaeologist Michael Herity, as his students examine a cross-inscribed slab of schist. Former Associate Professor of Archaeology at University College Dublin and currently president of the Royal Irish Academy, Herity, who was born in Donegal and has written extensively on this area, believes the best way to reach archaeology is in the field.

This year marks the 1400th anniversary of the death of Colmcille. As Herity leads his class from station to station along the Turas or pilgrimage route which begins and ends at a lateVictorian Protestant church, he speaks of the enduring presence of the saint in this area.

Although never formally canonised, Colmcille (also known by his Latin name, St Columba) is believed to have been born in 521. He was an aristocrat and holy man and central inspiration to a monastic tradition which extended to Iona, Kells in Co Meath and by the 12th century to Derry. No historical evidence exists to confirm that he ever lived in this part of Co Donegal, though he was a Donegal man by birth, having been born in Garton about 40 miles to the north-east of here. The folklore, however, is overwhelming. It is impossible not to feel convinced Colmcille once walked the hills and fields Herity leads us along. Standing by St Colmcille's chapel, a small, roofless, rectangular structure with its entrance on its east wall - suggesting that it was not originally built as a church - Herity the archaeologist debates some historical points with Charles Doherty, a lecturer in early Irish history at UCD.

Glencolmcille is extremely rich in archaeological evidence, much of which is linked to Colmcille's story and the fact that he may have lived as a hermit here. However, the historical evidence relating to him is non-existent. Does Doherty the historian accept that Colmcille lived here?

"There is no evidence. Historians deal in facts. He may well have been here, we can't say he was. But we can't say he wasn't either."

Earlier this week Doherty had discussed Adhamnan's Life Of Colmcille. Written 100 years after the death of the saint on Iona in 597, Adhamnan's work an's work written in and for an established monastic community is is more concerned with describing the extent of Colmcille's sanctity than in providing the facts of his life. Glencolmcille is not even mentioned in the book, which instead offers the first major instalment of the legend of St Colmcille, a story which continued to develop and change.

Doherty praises the physical beauty of the manuscript, which is composed in Hiberno Latin, as well as stressing its importance as an example of hagiogaphy. Adhamnan, like Colmcille, was an aristocrat and scholar. The 9th Abbot of Iona until his death in 704, he was not concerned with writing biography as historical record. His intent, Doherty argues, was more complex. In addition to presenting the many virtues of Colmcille as a holy man and detailing the various miracles attributed to him, he was also engaged in writing for the society of his own time.

Herity asks his class of archaeologists (rapidly turning pilgrims) for their views on the long flagstone in the north corner of the small church. Several voices predictably identify it as a "leaba". Possibly a tomb-shrine: a relic of St Colmcille may or may not lie there.

A discussion begins about the clay which lies beneath it, which is believed to possess special properties including the protection against fire and a cure for headaches and other ailments. A woman mentions how an Irishman who brought some of the holy clay from Colmcille's birthplace to Australia found his own house surviving bush fires which devastated those of his neighbours.

A large stone nearby is also unique, Leach na Bown (the flat stone of the requests) bears an inscribed cross. It is believed to grant wishes to pilgrims willing - and able - to leap from its highest point before walking three times around it, saying the required prayers.

Further up along a gradual slope at the foothill of Beefan Mountain the pilgrim/archaeologists reach a large cairn which surrounds St Colmcille's well. Tradition obliges devout pilgrims to add three stones to the mound of rocks before proceeding to the well to drink the holy water. The size of the cairn testifies to the number of pilgrims who have abided by the ritual.

Long before the Christian era, the valleys of Glencolmcille supported Stone Age farmers. Several examples of terrace farming remain, as does a superb array of megalithic tombs.

The court tomb at Cloghanmore in Malin More, with its two decorated entry stones, built in the Stone Age on good land, was eventually submerged by peat. Dug out of the bog in the 19th century it was first formally described by Sir Samuel Ferguson in 1864. It is one of the finest court tombs in Ireland.

Back in the village, observers from various countries gesture busily and speak non-stop. Even if you can't understand Icelandic, it is obvious the visitors are describing the field monuments of Glencolmcille.

St Colmcille would have approved of the internationalism of this cultural centre - probably the only place in Ireland the sun has been shining this week.