SANTILLANA DEL MAR, Spain: Some of Europe’s most spectacular prehistoric cave paintings reopened to a handful of visitors for a glimpse Thursday after a 12-year closure.

Renowned for vivid paintings of bison and animal-headed humans, the cave at Altamira in northern Spain shut in 2002 because scientists said the breath from visitors was damaging the prehistoric paint.

Now it’s reopened to select groups of visitors wearing masks and overalls, the Culture Ministry said, while experts assess the impact on the paintings.

A highlight is a set of 14,000-year-old paintings of red and yellow bison plus horses, deer, humans with the heads of animals and mysterious symbols.

The area became a World Heritage Site in 1985, as “masterpieces of creative genius and as humanity’s earliest accomplished art.”

The cave, whose walls are covered with paintings over more than 270 meters, was discovered in 1868 at Santillana del Mar, in the Cantabria region.

Experts say the cave was inhabited 35,000 to 13,000 years ago.

The paintings are “exceptional testimonies to a cultural tradition and ... outstanding illustrations of a significant stage in human history,” UNESCO says in its listing.

The techniques of the paintings and realistic animal details, it continues, mark “one of the key moments of the history of art.”

During the closure, visitors have had to look at a nearby replica of the paintings and only experts have been allowed into the cave.

In January, the foundation that manages the cave said it could reopen to groups of five people a week and for just 37 minutes at a time.

Overall, 192 visitors will be allowed in by August, when experts will reassess the impact of the visits on the paintings.

“The aim is to analyze the impact of human presence on the conservation of the cave,” Junior Culture Minister Josa Maria Lassalle remarked last month, “to determine if continued access to the cave is possible or not.”