Sidrón Cave - Credit: Wikimedia Commons
The Sidrón Cave () is a non-carboniferous limestone karst cave system located in the Piloña municipality of Asturias, northwestern Spain, where Paleolithic rock art and the fossils of more than a dozen Neanderthals were found. Declared a "Partial Natural Reserve" in 1995, the site also serves as a retreat for five species of bats and is the place of discovery of two species of Coleoptera (beetles). Read more on Wikipedia
Source: en.wikipedia.org