The standing stones of Carnac can be seen from the road travelled by Tour de France bicyclists as they pass. Dozens of ancient sites are in the area and the menhirs (standing stones) of Carnac are estimated to be more than 5000 years old.
Similar standing stone arrangements are found throughout Europe dating from the Neolithic to Bronze Age periods. Although archaeologists believe they were used for some ritualistic purpose it is not known what their use actually was. It is doubtful they had anything to do with astronomical events.
There are about a dozen alignments of standing stones in the Carnac area, the longest has ten rows of stones with more than 1100 stretching for a distance of more than one mile.