Perhaps among the most famous expeditions to pursue the secret to eternal life was that of explorer Ponce de Leon.
Prior to his first expedition to Florida, de Leon heard a story from native Caribbean islanders of a fountain of youth that would restore the vitality of anyone who swam in its waters. In the course of searching for the Fountain of Youth, as well as other riches on behalf of the Spanish crown, de Leon would explore what would become the state of Florida.
Stories of de Leon's quest to find the fountain only emerged after his death, so he may in fact never have sought the fountain. Today, however, St. Augustine, Fla., the oldest city in the United States, hosts a tourist attraction for the Fountain of Youth as a tribute de Leon's journey.