Reproduction of a bison from one of the Altamira cave paintings
Source Wikimedia Commons. Image credit Rameessos
BBC News Europe reports today that –
Spain’s famous Altamira caves are briefly being opened to the public, for the first time in 12 years. Five elderly Spaniards chosen in a draw can marvel at its ice-age paintings of bison, bulls and other animals. The visit, including time accessing the caves, will last only about half an hour – allowing the group just eight minutes to admire the paintings.
During the visit, dozen of sensors will monitor changes in the cave’s temperature and humidity, to see if more visitors can be allowed in in future, our correspondent says. As part of the experiment, a total of 192 people will be allowed to see the paintings in weekly visits until August, El Pais newspaper reports. Despite the historic nature of the viewing, taking pictures will not be allowed. Nor will visitors be allowed to touch the rock. They will be also dressed in protective clothing, to help prevent contamination of the site.
The caves were closed in 2002 to protect the paintings from microbiological damage caused by visitors. Perhaps they should stay closed to the general public. These 22,000 year-old paintings are just too precious and too vulnerable to risk further degradation from public viewing – no matter how small and restricted those viewings may be. 
Full BBC article here. Includes an excellent video, presented by Andrew Graham-Dixon, showing a visit to the replica Altamira caves housed in the National Museum and Research Center of Altamira.