White terraced thermal pools above the ancient city of Hierapolis in Turkey. Inscribed 1988.
From Wikipedia
Pamukkale, meaning "cotton castle" in Turkish, is a natural site in Denizli Province in southwestern Turkey. The area is famous for a carbonate mineral left by the flowing of thermal spring water. It is located in Turkey's Inner Aegean region, in the River Menderes valley, which has a temperate climate for most of the year.