The Cave of Altamira
The "Sistine Chapel of prehistoric art" is just a few minutes from Santillana del Mar.

Just a few minutes from Santillana del Mar lies one of the most important places in human history: the Cave of Altamira.
Discovery
The paintings were discovered in 1879. According to legend, it was the young daughter of the amateur archaeologist Marcelino Sanz de Sautuola who first looked up at the ceiling. For a long time experts doubted that Stone Age people were capable of such art – only decades later was its authenticity widely accepted.
The paintings
The cave is best known for its ceiling with polychrome bison. The artists used the natural bulges of the rock so that the animals look almost three-dimensional. The oldest images in the cave are tens of thousands of years old. Altamira has been a UNESCO World Heritage Site since 1985.
Visiting today
To protect the paintings, the original cave is largely closed. Instead, the Museo de Altamira has the Neocueva, a very accurate replica of the cave. It gives a good impression of what it looks like inside, and the museum vividly explains life in the Palaeolithic.
A visit combines perfectly with an afternoon in Santillana del Mar.