Cotton Castle, known as Pamukkale, is a natural thermal spring located in southwestern Turkey. It features stunning white travertine terraces formed by the deposition of calcium carbonate from the hot springs. The mineral-rich waters flow down the mountainside, creating a unique landscape that attracts visitors from around the world. The site has been recognized as a UNESCO World Heritage Site due to its geological significance and historical importance. Nearby, the ancient city of Hierapolis offers ruins and structures, including a well-preserved theater and ancient baths, providing insight into the region's rich history and culture.