Particularly renowned are the sites of Gran Dolina, Sima del Elefante and Sima de los Huesos. The latter is home to the world’s largest accumulation of human fossils from the Middle Pleistocene.
In 1994, human fossils dating from 850,000 years ago were found at the Gran Dolina site. Later, in 1997, Science magazine described them as a new species of the Homo genus: Homo antecessor. The oldest human fossil in Europe was found in 2007 at the Sima del Elefante site. It dates back 1.2 million years. The significance of these finds and the related research merited the Prince of Asturias Award, which the research team received in 1997.
In 2000, the sites were declared UNESCO World Heritage Sites. They are supplemented and promoted by the Museum of Human Evolution, which was opened in July 2010. The museum is located in a unique modern building that displays the most noteworthy pieces from the excavations. It adjoins the National Centre for Research on Human Evolution.