Ancient Civilizations: Lost Worlds of the Past explores the legend of Lyonesse, a mythical land believed to have existed off the coast of Cornwall before being swallowed by the sea in a catastrophic flood. Said to be a land of great cities and noble knights, Lyonesse is deeply tied to Arthurian legend and the story of Sir Tristan. While some believe it was inspired by real geological changes in the Isles of Scilly, no definitive proof has been found. The tale of Lyonesse remains a powerful symbol of lost civilizations and the relentless forces of nature.