The prehistoric paintings of Grotte de Niaux, unfortunately, cannot be photographed, but you can actually see the originals (in small groups). The cave itself is wonderful even without the paintings. Here are some pictures from the entrance to the cave.
entrance to cave
cave roof. Absolutely no bats, strangely enough.
view of the valley from the cave entrance. If you squint, there
is a castle roughly in the middle of the photograph.
That's all, folks!