Cave of Altamira in Santillana del Mar

You're standing at the Cave of Altamira, close to the historic town of Santillana del Mar in Cantabria, northern Spain. Here, in the limestone of Mount Vispieres, lies one of the most famous caves in the world. From outside you don't see much. Around thirteen thousand years ago a rockfall sealed the entrance. That kept everything inside safe, until a fallen tree disturbed the rocks.