Panoramic view of travertine terraces at Pamukkale | Turkey

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. The ancient Greco-Roman and Byzantine city of Hierapolis was built on top of the white "castle". The area was is declared a World Heritage Site.

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Hierapolis was a prosperous city in the Roman province of Asia, situated above the junction of the rivers Lycus and Meander Rivers, 12 miles northwest of Colossae, 6 miles north of Laodicea and 100 miles east of Ephesus. Little is known of its early history. It may have originated as a Phrygian cult center, from which it took the name Hieropolis "city of the heiron" (sanctuary). The city itself is usually said to have been founded around 190 BC by king Eumenes II of Pergamum, with the official name of Hierapolis, possibly derived from Hiera, wife of King Telephos, the legendary founder of Pergamum.