Seventeen decorated caves of the Paleolithic age were inscribed as an extension to the Altamira Cave, inscribed in 1985. Altamira is located in the Franco-Cantabrian region and declared a World Heritage Site by UNESCO as a key location of the Cave of Altamira and Paleolithic Cave Art of Northern Spain.

The prehistoric parietal cave art features charcoal drawings and polychrome paintings of contemporary local fauna and human hands. The earliest paintings were applied during the Upper Paleolithic, around 36,000 years ago. The site was only discovered in 1868 by Modesto Cubillas.

Aside from the striking quality of its polychromatic art, Altamira’s fame stems from the fact that its paintings were the first European cave paintings for which a prehistoric origin was suggested and promoted. Marcelino Sanz de Sautuola published his research with the support of Juan de Vilanova y Piera in 1880 to initial public acclaim. However, the publication of Sanz de Sautuola’s research quickly led to a bitter public controversy among experts, some of whom rejected the prehistoric origin of the paintings on the grounds that prehistoric human beings lacked sufficient ability for abstract thought. The controversy continued until 1902, by which time reports of similar findings of prehistoric paintings in the Franco-Cantabrian region had accumulated and the evidence could no longer be rejected.

The cave is approximately 1,000 m meters long and consists of a series of twisting passages and chambers. The main passage varies from two to six meters in height. The cave was formed through collapses following early karst phenomena in the calcareous rock of Mount Vispieres.

Archaeological excavations in the cave floor found rich deposits of artifacts from the Upper Solutrean (c. 18,500 years ago) and Lower Magdalenian (between c. 16,590 and 14,000 years ago). Both periods belong to the Paleolithic or Old Stone Age. In the two millennia between these two occupations, the cave was evidently inhabited only by wild animals. Human occupants of the site were well-positioned to take advantage of the rich wildlife that grazed in the valleys of the surrounding mountains as well as the marine life available in nearby coastal areas. Around 13,000 years ago a rockfall sealed the cave’s entrance, preserving its contents until its eventual discovery, which occurred after a nearby tree fell and disturbed the fallen rocks.

Human occupation was limited to the cave mouth, although paintings were created throughout the length of the cave. The artists used charcoal and ochre or hematite to create the images, often diluting these pigments to produce variations in intensity and creating an impression of chiaroscuro. They also exploited the natural contours of the cave walls to give their subjects a three-dimensional effect. The Polychrome Ceiling is the most impressive feature of the cave, depicting a herd of extinct steppe bison in different poses, two horses, a large doe, and possibly a wild boar.

Dated to the Magdalenian occupation, these paintings include abstract shapes in addition to animal subjects. Solutrean paintings include images of horses and goats, as well as handprints that were created when artists placed their hands on the cave wall and blew pigment over them to leave a negative image. Numerous other caves in northern Spain contain Paleolithic art, but none is as complex or well-populated as Altamira.

In 1879, amateur archaeologist Marcelino Sanz de Sautuola was led by his eight-year-old daughter María to discover the cave’s drawings.[7] The cave was excavated by Sautuola and archaeologist Juan Vilanova y Piera from the University of Madrid, resulting in a much acclaimed publication in 1880 which interpreted the paintings as Paleolithic in origin. The French specialists, led by Gabriel de Mortillet and Emile Cartailhac, were particularly adamant in rejecting the hypothesis of Sautuola and Piera, whose findings were loudly ridiculed at the 1880 Prehistorical Congress in Lisbon.

Due to the supreme artistic quality, and the exceptional state of conservation of the paintings, Sautuola was even accused of forgery, as he was unable to answer why there were no soot marks on the walls and ceilings of the cave. A fellow countryman maintained that the paintings had been produced by a contemporary artist, on Sautuola’s orders. Later Marcelino Sanz de Sautuola found out the artist could have used marrow fat as oil for the lamp, producing much less soot than any other combustibles.

It was not until 1902, when several other findings of prehistoric paintings had served to render the hypothesis of the extreme antiquity of the Altamira paintings less offensive, that the scientific society retracted their opposition to the Spaniards. That year, Emile Cartailhac emphatically admitted his mistake in the famous article, “Mea culpa d’un sceptique”, published in the journal L’Anthropologie. Sautuola, having died 14 years earlier, did not live to witness his rehabilitation.

Further excavation work on the cave was done by Hermilio Alcalde del Río between 1902–04, the German Hugo Obermaier between 1924–25 and finally by Joaquín González Echegaray in 1968.