I'm posting this too late, I know, to be of any use to Vicster's April trip to France.
But others thinking of heading down to 'Le Midi' might be interested in looking into our particular corner of the megalithic world : the dolmens of the Languedoc and Pyrenees. And while our departement may not have the sheer quantity of 'old stones' that others do - we can claim two of the largest dolmens, and the biggest menhir in southern France [and one of the largest in Europe, at 20 feet and 50 tons]. Size might matter to some - but measurements are only one aspect of the story.
The flux of life of the Pasteurs des Plateaux, those late Neolithic/Chalcolithic/Early Bronze Age hill-tribes that peopled the slopes of the Cevennes, the Causses of Languedoc, the Garrigues of Roussillon and the Soulanes of the Pyrenees, can be traced through their dwellings and workshops and burial places, from high up in the mountains of Cerdanya, to close by the lagoons of the Mediterranean (where seeds of cannabis sativa and opium have been found in Neolithic ports . . .).
Most of the sites I research are small and unimpressive compared to some of the well-trodden places of northern Europe.
My aim is to find them - using maps and satellites, occitan/catalan etymology and toponymy, internet and local historians, folk history and 'Victorian gentleman-scientists' - and to write about them before they disappear.
Discovering where these peoples were buried is one thing. Answering Vicster's memorable question: "Where the bloody hell did they live?" - is just as fascinating - and I'm now getting to grips with a whole other connected range of research.
If any of this interests you, then please visit www.dolmen.wordpress.com
Roc [ Richard, in the Languedoc ]
NB Try www.geoportail.fr if you are interested in France. It's the national map service online, with a changeable scale, and fadeable maps, and a 3D function that lets you fly around on a mapped GoogleEarth-type interface.