Your News Feature about the Lascaux cave, “The film crew” (Nature 433, 100–101; 2005), expresses the hope that, thanks to new technologies, “tourists will get their chance to see the real version of this ancient site”. Unfortunately, the history of Lascaux's conservation since its discovery in 1940 leads one to expect the opposite. Today, the cave is closed even to experts in rock art.

Contrary to your report, the cave's climate did not return to its original state after the 1963 closure. How could it? Several hundred cubic metres of soil had been removed between 1940 and 1958, when an air-conditioning system was installed. The green algae, mosses and bacteria were eventually eradicated from the walls, but the growth of small white calcite crystals on the surface caused by rises in temperature, humidity and carbonic gas associated with visitors to the caves could only be stopped, not reversed.

Lascaux remains extremely fragile. The 2001 invasion of the floor by white Fusarium fungi and the (fortunately limited) appearance of black spots on the ceiling remind us of the dangers of interfering with rock-art sites. The best technology for preserving them is to leave them alone.