Okay, so if you want to split hairs, maybe we did leave France. We went to the enclave of Spain which is inside of France. It's called Llivia and here are a couple of maps. It is not very large, perhaps a few square miles in size, but it is very strange. We sat down at a table at a restaurant and heard "Hola! Como esta?", not "Bonjour, Monsieur et Madame." The menus were in Spanish, French, English and German. All the signs were in Spanish and we no longer saw French banks, but Spanish ones. We were in Spain, but we really hadn't left France. If I hadn't known about it being an enclave of Spain, we would have been even more mystified because there were really no indications that you were technically in Spain. But suddenly, everything changed. It reminded me of riding our bikes through Belgium and passing from French speaking Flanders into the territory of the Walloons, who speak Dutch. The signage, the architecture, the signs of affluence, the general tidiness of people's property, it all changed and we, in our ignorance, wondered why.
Llivia has a strange history which as best I can relate in 25 words or less, is that some Duke or Poobah or Spanish potentate decided he didn't want to join France when they drew up the boundaries, and France didn't feel like fighting another war over the matter.