Pamukkale, Turkey © bybostanci/Getty Images
The stunning travertine terraces and hot pools of Pamukkale, Turkey, have dazzled visitors since at least the end of the 2nd century BCE, with the founding of the Greco-Roman thermal spa of Hierapolis. Since then, people have enjoyed a relaxing soak in the 97-degree Fahrenheit water, claiming curative powers for many ailments.