These are the best:

http://www.themapcentre.com/acatalog/Online_Catalogue_IGN_Blue_Walking_Maps_57.html

1:25000 scale makes them the same as the orange OS maps. The mapping is close to, but quite up to, OS standards. Once you have the map you want you need to go over it, square by square, with a highlighter pen and find all the dolmens (which look like tiny picnic tables) and menhirs (tiny isosceles triangles), otherwise you'll end up missing them once you're out and about....

Enjoy

We also used Bruno Marc's books which we borrowed from Spaceship Mark, but got from Amazon.Fr when we got back in case we get a chance to go again. They're in French & neither of us are that good at French but I found that with reasonably occasional use of a French/English dictionary & in conjunction with the maps Spaceship Mark recommended we did ok.

There are also quite a few websites but they tend not to be too good on telling you where the things are. I think that's partly coz Bruno Marc seems to have a finger in many of them & he probly wants folks to buy his books!

This was probly one of the most useful sites I found, tho it's not that easy to use & some sites are not placed quite right http://www.t4t35.fr/Megalithes/AfficheSelectDep.aspx?Projet=France

This site http://dolmen1.free.fr/oc/cartes.html has maps based on Bruno's books, but they're quite difficult to 'match up' to any printed maps!

Hereare a cupple more that I bookmarked but I'm not how useful they actually were http://zebuprehisto.unblog.fr/les-dolmens-a-st-felix-de-pallieres/, http://dolmen3.free.fr/lot/ & http://dolmen2.free.fr/oc2/index.html (which seem related to the one in the previous para but I'm not sure how!)

A lot of the time I was reduced to grabbing the name of a site from one of the websites & googling it - often without much success. If you can afford it, I'd deffo recommend the Bruno's books/Spaceship Mark's recommended maps route!!!

Where are you actually staying? A word of warning - a lot of them take a bit longer to get to than you expect!! Once you get close, quite a few are signposted, but the signposts are a bit hit & miss for some, taking you some of the way & then disappearing!

But megaliths were slightly secondary to Van Gogh places on our trip - we were staying over to the east (in Arles). It's not where you'd choose for dolmens, so the stuff we've posted tends to be a bit more over that way. Other than the ACE rock-cut stuff around Arles itself there's not much very close to Arles.

Actually, I've still got some more sites to add here - just never have time.... :^(

I'm assuming you've seen J's blogs?

http://www.themodernantiquarian.com/post/63029/weblog/
http://www.themodernantiquarian.com/post/62865/weblog/
http://www.themodernantiquarian.com/post/62864/weblog/
http://www.themodernantiquarian.com/post/62797/weblog/

(I think that's all of them.)

:^D

love

Moth

Another word of caution regarding French maps. I bought a few maps last year prior to a trip to Provence. I thought I'd buy them directly from IGN to ensure the latest editions http://www.ign.fr/ The maps arrived promptly so no problems at all with that.
I'm not sure how often IGN update their maps, the ones that they sent me ranged from 1999-2005 consequently I found a bunch of stones situated within the middle of a well- established suburban housing estate which were shown as being in farmers fields on the map. I guess France is a big country and re-mapping it must take a bit of time.
Also the roads had all been re-numbered since my 1999 edition map so there was a fair bit of guesswork done.
All part of the fun of being abroad