On my way to stay with friends in Beynac, I stopped in Poitiers. It's a not very big place, with a whole lot of churches.

At one point in time, I'm quite sure the building of churches was simply part of the local economy, because everyone was probably of the same denomination and I don't think the population was ever such that they needed to build "overflow" churches.

I have no idea though; I was on vacation and too lazy to look into it.