Pay a visit to Musee de Carnac and gain an insight into past civilizations. Who knows, you may even discover some unusual traditions and beliefs you never even knew existed.
You'll have sightseeing choices galore in Carnac. Musee de Carnac is a good place to begin here, but there are loads of other worthwhile places to consider. Carnac Beach, Locmariaquer Megaliths, and Kerhillio Beach are close to the exhibition of human history and and will cap off your day nicely.