In the Asterix comic books you only had to drink a magic potion to be able to lift a menhir. But in reality you need vast quantities of muscle power and lots of patience.
That is what a group of 30 holiday-makers found out when they heaved on a rope to move a 4.2-tonne stone block as part of an experiment probing the mysterious history of megaliths in France's northwestern Brittany region.
"It's experimental archeology," explained Cyril Chaigneau, an architect who runs a programme on the megalithic sites of Petit Mont and Gavrinis in the Gulf of Morbihan.
"We're trying to find out how men from the neolithic period moved enormous blocks across distances of 10 kilometres (six miles) or more," he said.
In the Asterix series, the eponymous Gaul's sidekick Obelix was a menhir delivery man in the Roman era of the first century BC, but in reality the region's megaliths were carved much further back in prehistory.
No-one today knows how or why the sedentary tribes that settled 7,000 years ago on this stretch of the Atlantic coast transported and then erected the menhirs, dolmens and other huge stone steles that dot the Breton landscape.
Chaigneau's investigation focuses on the journey of a slab that makes up part of the dolmen on the island of Gavrinis, an engraved block of 17 tonnes that serves as the ceiling of a funeral monument built in 3,600 BC.
Work carried out by other archeologists has established that this slab was in fact a fragment of another dolmen five kilometres away.
That huge structure was erected a thousand years earlier and stood 25 metres tall (82 feet), was three metres wide and weighed around 300 tonnes. The stone it was made of came from a quarry situated ten kilometres away.
"The goal is to reconstitute the journey by land and sea or river but also to help members of the public get a practical understanding of prehistory, to engage the public in science in action," said Yves Belfenfant, the director of the sites of Gavrinis and Petit Mont.
Elisabeth, a banking executive from Versailles, was one of the 30 people trying to move the massive stone.
She said she and her husband and their five children liked "cultural" holidays and that was why they wanted to take part in this experiment.
"It's impressive to see this massive stone moving," she said.
The tourists managed to pull the stone 4.4 metres in about 12 minutes on their first stint, but by their fifth try their technique had improved and they pulled it 22 metres in 24 minutes.
Jerome, a 36-year-old father, said he was taking part because he had "always wondered how the Egyptians built the pyramids."
"This is far better than school to help you understand," said nine-year-old Valentine, who was proud of her part in pulling the giant stone forward across logs laid on the ground.
"You don't need magic powers to move a block, you just need a lever," said Chaigneau, who has programmed several stone-pulling events for holiday-makers throughout the summer season.
The first such experiment in France was held in Bougon in western France in 1979, when 150 volunteers helped shift a block of 32 tonnes.
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