5. Atlantis
The mythical lost city of Atlantis has been featured prominently in literature for thousands of years, dating back to the ancient works of Plato. Some say the Greek island of Santorini is the site of the ancient city, long ago sunken beneath the depths of the sea. Others insist on an underwater rock formation located in the Bahamas. We'll never really know, but we're going to continue believing in the myth anyway.