Hot water springs saturated with limestone have modelled the strange landscape of the "cotton castle". Basins and pools overlap and stand one on top of the other like an opencast mine, cascading along the cliff and dotted with striking white stalactites like something out of a fairy tale. Under the Romans, Pamukkale was already a spa resort of some repute, then known as Hierapolis, and remains of Greek baths and other monuments are visible. Visits to the site, now a listed Unesco monument, are now highly supervised.