As a result of archeology, there is ample evidence that there have been civilizations that began, became advanced, and then vanished, sometimes for no reason. As a result, people have wondered what those lost civilizations were like. Fueled by stories that seem to be part history and part myth, entire concepts of lost civilizations have been created.
In the Atlantic, partially based on the writings of Plato, it is believed there had once been an advanced civilization on an island or continent called Atlantis. In the South Pacific, there is a belief there was an advanced civilization known as Lemuria or Mu. There are also believed to be lost civilizations off the coast of Florida, and in various parts of the US and other places.
The search for such lost civilization is in part based on a desire to learn if they had a science different from, and more advanced in certain areas, than our current science. However, the dream of finding an ideal place with people who lived healthy, extremely long and peaceful lives seems to be at the heart of many a searcher. One such lost civilization is completely invented in the book Lost Horizon by James Hilton. The name of his lost civilization, Shangri-La, has become synonymous with such dreams.