Pamukkale, meaning "cotton castle" in Turkish, is a natural site in Denizli Province in southwestern Turkey. The city contains hot springs and travertines, terraces of carbonate minerals left by the flowing water. Pamukkale's terraces are made of travertine, a sedimentary rock deposited by water from the hot springs. It is located in Turkey's Inner Aegeanregion, in the River Menderes valley.

Tourism is and has been a major industry. People have bathed in its pools for thousands of years. As recently as the mid-20th century, hotels were built over the ruins of Heropolis, causing considerable damage. An approach road was built from the valley over the terraces, and motor bikes were allowed to go up and down the slopes. When the area was declared a World Heritage Site, the hotels were demolished and the road removed and replaced with artificial pools. Wearing shoes in the water is prohibited to protect the deposits.