The Lascaux cave contains nearly 2,000 figures of animals, humans, and symbols. Some of the major images have been painted onto the walls using mineral pigments, but some have also been carved into the stone. The original cave is only open to VIPs, but France has done a remarkable job of recreating the cave nearby that is within centimeters of the actual shape. The only thing different from the original is the humidity and smell. The paintings and shape of the cave (built underground) is exact.
My recommendation would be to stay over night in Montignac. We stayed at the La Roseraie Hôtel. Very comfortable and friendly. Then the next day, we biked to the original cave and walked down to the re-make. In the winter, you can buy tickets at the cave, but in the summer, tickets have to be purchased in town. We waited for the English version of the tour and then were simply delighted!
The tour guide was an archaeologist and extremely knowledgeable. Would highly recommend!!!