Altamira is one of the most famous cases of modern archaeology having to correct itself. In 1879 the local landowner Marcelino Sanz de Sautuola was alerted to the polychrome bison on the cave's ceiling by his eight-year-old daughter Maria, who looked up during her father's dig and exclaimed "papa, bulls!" Sautuola argued that the paintings were Paleolithic; the leading archaeologists of the day rejected the claim, accused him of forgery, and disgraced him. As similar finds accumulated in the early twentieth century, Sautuola was vindicated — years after his death.

Altamira's so-called Polychrome Hall stretches eighteen metres and is crowded with some twenty-five bison alongside horses, deer and stencilled hands. The painters used the rock's natural bulges as the bodies of the bison, so the figures are not flat images on a wall but readings that follow the ceiling's three-dimensional contour. Their palette runs from red ochre and yellow earths to manganese black; they shaded with charcoal and combined engraving and rubbing with painting.

The paintings are not from a single moment. Uranium-thorium dating has shown that the cave was visited repeatedly across thousands of years — from the earliest marks around 36,000 BCE to the famous Magdalenian polychromes around 16,000–14,000 BCE.

Visitor humidity degraded the cave so quickly that it was closed in 1977; today a full-scale replica, the Neocueva, sits inside the nearby visitor centre. UNESCO inscribed Altamira in 1985 and broadened the listing in 2008 to include ten further northern Spanish caves.