The Cave of Altamira ( AL-tə-MEER-ə; Spanish: Cueva de Altamira [ˈkweβa ðe altaˈmiɾa]) is a cave complex, located near the historic town of Santillana del Mar in Cantabria, Spain. It is renowned for prehistoric cave art featuring 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 discovered in 1868 by Modesto Cubillas and subsequently studied by Marcelino Sanz de Sautuola.

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. 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.

Altamira is located in the Franco-Cantabrian region and in 1985 was declared a World Heritage Site by UNESCO as a key location of the Cave of Altamira and Paleolithic Cave Art of Northern Spain. The cave can no longer be visited, for conservation reasons, but there are replicas of a section at the site and elsewhere.