In December 1994 three spelunkers, led by Jean-Marie Chauvet, found a sealed-off cave in south-western France. They may have been the first humans to enter it for over twenty thousand years. On the walls of the cave are paintings that were made over thirty thousand years ago - the oldest known to exist anywhere in the world. The previous record-holders were, surprisingly, in Australia, but the Australian images aren't nearly as beautiful or evocative - it seems that even in Palaeolithic times, the French were better painters. The examples of cave art that you may remember seeing images of are from the Lascaux caves, also in France, which are about half as old as this more recent find.

The Chauvet cave was soon closed to the general public and even the few admitted have severely restricted access. But the French government decided to allow one filmmaker in, and chose German director Werner Herzog. They made exactly the right choice. For a couple of decades Herzog has been alternating between fiction and documentary, inflecting both with his inimitable sort of lyrical mysticism so that even the documentaries, rigorously accurate though they are, feel like fiction. It's hard to credit in advance how much Herzog can wring out of a simple subject like this. This extraordinary documentary is as close as you will ever be able to come to seeing these strange and most ancient of all paintings.