There are other hypotheses about the Carnac boulders, carbon dated to 4000 to 2000 BC. They mark one of Caesar's camps during the Gallic Wars from 58 to 50 BC. Or they were snake worship sites for ancient Celts whose territory included parts of England and Ireland as well as Brittany. Or maybe they were goblin lairs and fairy treasures. But St. Cornelius works for me.
It's the same story with other prehistoric monuments in Western Europe. No one knows for sure who built them or why, although sites have been found, from Scandinavia to Spain, that have various configurations: upright stones, known as menhirs or megaliths, standing alone or in groups, as at Stonehenge, England; dolmens, Neolithic tombs made of massive boulders, laid on top of one another; and tumuli, or artificial mounds, where ancient man buried the departed under heaps of rubble.
My first encounter with these mysteries was at Avebury on the Wiltshire moors in England, a medieval village surrounded by concentric circles of standing stones. When Christianity arrived, villagers desecrated the megaliths, believing them evil. But on a recent trip to Brittany — whose coast must have fit together with that of England like a puzzle piece before a lowering sea created the English Channel — I discovered that the Carnac megaliths fared better. Although sometimes mined for building material or marked with Christian crosses, they have otherwise escaped the wrath of superstitious zealots in one of the earliest instances of French laissez faire.
It takes about four hours to drive from Paris to Carnac, which occupies a segment of the ragged Brittany coast near Quiberon Island and the mouth of the Morbihan Bay. Once one of the poorest, most isolated corners of France, it is now one of the most chic, not because of the megaliths but because of the beaches colonized almost equally by French and English vacationers.
Carnac's old port, La Trinité-sur-Mer, is as full of sails and topsiders as Hyannis, Mass., reached along a waterfront road lined by handsome summer houses, thalassotherapy spas, nature preserves, salt marshes and sandy Atlantic Ocean shores. A tourist train takes sightseers along the Carnac Riviera and through the town center with its Museum of Prehistory, market square and 17th century church dedicated to St. Cornelius.
The first thing I saw when I drove into town was the whitewashed chapel of St. Michel atop a 30-foot tumulus that covered a tomb that contained prehistoric axes and ornaments. At its foot is the Hôtel Tumulus, built as a residence in 1900 by St. Michel excavator Zacharie Le Rouzic. It's still run by family members and thus an ideal place for amateur archaeologists. I checked into a simple, sunny room under a gable, swam in the pool and dined on fresh fish in the veranda restaurant.
The next morning I started at the Maison des Mégalithes, an interpretive center for the Carnac stone alignments. This would have delighted Prosper Mérimée, the inspector-general of French historical monuments who encouraged scientific study of the site in the early 1800s.
The center's exhibitions and video presentation clarify important facts. For instance, four to six millenniums ago the forest-bounded fields where the stones stand would have been an empty moor, like those around Avebury. At that time, man had learned to farm and domesticate animals, placing him in the stage of development known to archaeologists as the Neolithic, which occurred between the hunter-gatherer Mesolithic and the Bronze Age. This corner of Brittany is thought to have supported 30,000 to 50,000 Neoliths, who, their remains suggest, were at least a foot shorter than modern man. Besides farming, they traded widely, importing decorative objects found in tombs from as far away as Italy and Spain.
But it's what Neolithic man did at the Carnac alignments, which begin just north of the interpretive center. Altogether, there are seven fields of standing stone, stretching northeast for about two miles. To see them, most visitors drive slowly along the country road that parallels them, pausing at specific alignments for closer inspection, though most are surrounded by chain-link fence.
I made my first stop at Kermario, which has 982 menhirs laid in straight rows, increasing in size from east to west where some are almost 10 feet tall, and the ranks give way to what is thought to have been a temple compound. On a stormy night the stones might have struck me as eerie, but on a dewy spring morning, with fields carpeted in new grass and dandelions, I felt only awe at the engineering and some fellow feeling for Neolithic man who, although pagan, was clearly religious.
An old mill and lake separate Kermario from Le Manio, a smaller alignment that includes the Manio Giant, a lichen-covered granite slab 18 feet tall on which snake engravings are dimly visible near the base.
The Manio Giant is not the biggest megalith in the region. That honor belongs to the Grand Menhir, erected around 4500 BC on the nearby Locmariaquer Peninsula, which I visited later that day. It stood 60 feet high before broken into the four massive pieces now lying in a field near another tumulus and decorated dolmen. Archaeologists think the granite slab, weighing about 280 metric tons — more than 600,000 pounds — came from quarries about six miles away. To put the feat of its transportation in perspective, an experiment in 1979 showed it would take 200 people to drag a 10-tonne block (about 22,000 pounds) 300 feet in a day.
Monoliths like the Grand Menhir, tumuli and dolmens are scattered around southwestern Brittany. I saw signs marking them wherever I drove. But to see the great burial mound of Gavrinis you have to take a sightseeing cruise on Morbihan Bay, as I did, because the site is on a small, uninhabited island that would have been a hill in the Neolithic era when the sea level was about 20 feet lower than it is today.
The boat rounded the point where Gavrinis stands but did not stop, a pity because the walls of the excavated chamber inside are richly engraved with emblems that resemble writing, according to "Notes From a Journey in the West of France," by monuments minister Mérimée.
And then there are my favorite megaliths, hardly prehistoric. They appear in two panels on the western portal of the Carnac church, flanking Cornelius. He was the patron saint of cattle, which is why the paintings feature cows, placidly waiting for milking time among fields of prehistoric stone.