Good evidence that parts of this region will have other influences from Europe and not just France.
Actually I believe the entire region is based off of France, even the icy mountain at the top right that looks like it should be located in Belgium or Germany when comparing to a real map. (I am certain that icy mountain is based off one of the French Alpes, by the way.)
The place with stones is based off of a commune called 'Carnac' in France. Look it up on google maps, they are placed almost in the exact same spot. Carnac is renowned for it's 'Carnac stones' or rather menhirs (standing stones) surrounding in all sorts of different formations around the area.
As for the few islands to the top left, I believe those are based off the Channel Islands.
Obviously Lumiose City is based off Paris. Not sure about the rest, I have some ideas but they aren't concrete ones.
I guess it doesn't really matter what's based off of what. I just think it's cool to know the back story to it all. Sorry for getting carried away xD