Pellucidar
From Tardis Wiki, the free Doctor Who reference
Pellucidar was a location from various Edgar Rice Burroughs books; including the comic, Tarzan at the Earth's Core. It was an underground world which features prehistoric fauna including dinosaurs, Ice Age fauna, and Neanderthals.
According to the Seventh Doctor, Pellucidar was inspired by the capital city of the Silurians. (AUDIO: The Silurian Candidate)
