These are on the list of most tourists and are one of the major sites in Brittany.
The alignments are amazing with rows of stones stretching as far as the eye can see. Most people head to Maison des Megaliths where there is lots of parking and entry is free. There is a video presentation and the shop has a good selection of books with several in English (although mark up on those prices in pounds sterling is big. Postcards are also expensive. The toilets are in the car park and let them down. It is possible to climb onto the roof for aerial views.
The alignments are fenced off and during the summer months access to the stones is restricted to guided tours only to protect the vegetation. The web site says there are English tours in the height of the summer. There is a free information leaflet available in English from the Maison des Megaliths.
The road (Rue du Tumulus) running beside the alignments is busy and although there is a grass verge it in not advisable to walk along the road. There is a footpath running along the length of the stones on the side away from the road. Once away from the Maison des Megaliths you lose the crowds.
There are about 3000 stones arranged in lines which stretch for 4km across the landscape. Most are 1-2m tall. They are split up of the Alignments of Ménec, Kermario and Le Manio.
Most people visit the Maison des Megaliths and the Ménec alignments and then drive past the rest. Although there is little parking along the road, many people pull off onto the verge so there is a need to watch out for pedestrians who in their excitement to see the stones forget about traffic. Another hazard is the Tonka Train which trundles slowly along the road while passengers take photos. Traffic builds up behind it and it is impossible to overtake.
There are smaller car parks for the Kermario alignements. Further on is a layby on the roadside near a footpath which cuts across the alignment to the old windmill. Climb this for one of the best aerial views of the alignments. It is much better than that from the top of Maison des Megaliths.
There is a small parking area just off the road before the Equestrian Centre for the Kerlescan Alignments. It is 15-20 minute walk through the trees to the Manio Quadrilateral, a large rectangle of stones, thought to be the remains of an enclosure round a long gone dolmen. Close by is the impressive 6m high GÉANT, a single standing stone.
Don’t miss the alignments at Le Petit Menec. There is a footpath signed to these from Kerlescan but they are not signed from the road. Turn left onto D186 and after about 2150m there is a right turn onto a minor road into the forest. Drive down this for about 400m and there is a small parking area on the left and the stones are on your right. There are three rows of stones among the trees. Some have been used as part of a stone wall. Few people find these stones and you are able to wander freely among them. It is a delightful place.
For more information: http://en.wikipedia.org/wiki/Carnac_stones