About 6,000 years ago, when Rome was but a couple of goat sheds and the pyramids were still waiting for planning permission, a prehistoric crowd was hanging out in Ceide, Co Mayo, on the west coast of Ireland. With a mild climate, year-round grazing and a view of the sea, Ceide had plenty to offer the upwardly-mobile neolithic family.

Although remains of this cliff-top farming settlement are still being excavated, the site is open to the public. Ceide's rambling dry-stone walls and homesteads are being claimed as Europe's largest Stone Age monument. For anyone seeking an escape from Aran jumpers, inflatable leprechauns and long-winded folk songs, the windswept fields of Ceide could be a breath of fresh air.

So what happened to the settlement that was Ceide? In about 3,000BC a combination of deforestation and a change to a cooler, wetter climate meant the fields became increasingly waterlogged: so much so that the settlement was abandoned and left to turn into bogland. But, rather like a slow-motion Pompeii, the homes, farms and tombs of Ceide were preserved in the process, with the landscape of 5,000 years ago kept intact beneath the soggy blanket of the bog.

The remains of Ceide were discovered by a farmer cutting turf for fuel. Now rich, black layers of turf are being peeled back to reveal the outlines of homes and the field plans of a large, well-organised community, apparently sufficiently at peace with its neighbours not to need defensive walls.

An explanation of Ceide's prehistory is provided by an exhibition in a pyramid- shaped visitor centre, dramatically perched on cliffs overlooking the Atlantic. Exhibits show how the inhabitants of Ceide might have lived and how rotting vegetation formed the banks of turf that now cover the hillside, several metres above the ground level of the neolithic farmland. By the time the Egyptian pyramids had been built there was an ankle- deep layer of bog over Ceide; and by the time Athens had reached its Classical peak, the bog was waist-deep.

The most striking thing about Ceide is not so much the sheer stretch of time that has elapsed since the fields were last open to the sky, but a remarkable sense of continuity. Give or take a few telegraph poles and Japanese tractors, the farming landscape of Mayo still has much in common with its ancient past. The design of stone walls put up 200 generations ago is more or less the same as that used by the modern small farmers of Mayo.

The exhibition also compares the design of a stone-walled house excavated at Ceide and the traditional Irish cabin. These are not remains of the palaces of powerful people, but of ordinary homes which would not look that out of place among today's dry-stone, whitewashed cottages.

Take almost any road from Ceide, and you will find a wealth of other ancient sites: standing stones, ring forts, tombs and underground chambers. In the parish of Killasser in Co Mayo, a lecturer from University College Galway found more than 300 prehistoric monuments, including more neolithic stone walls in the village of Cullen.

It almost seems as if there was some sort of Stone Age overcrowding here, in stark contrast to the present concern about depopulation. The local airport at Knock is doing good business flying young people to London and New York, looking for work that they cannot find at home. In such circumstances, Ceide has a contemporary relevance in attracting tourists and helping to create employment.

Bus-loads of Americans wearing shamrock-emblazoned windcheaters are no longer the stock-in-trade of the local tourist industry. Now, eco-conscious Germans and Scandinavians dressed in yellow cagoules and oatmeal jumpers have discovered the west of Ireland. While these environmentally friendly visitors come here seeking an unspoilt landscape, Ceide Fields is a reminder that a lot of living has already taken place in the west of Ireland.

Ceide Fields, Ballycastle, Co Mayo (010 353 96 43325). The visitor centre is open daily 9.30am-6.30pm. Admission: adults pounds 2; senior citizens pounds 1.50; children pounds 1; family ticket pounds 5.

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