Adjacent to Pamukkale lies Hierapolis, an ancient Greco-Roman city. Founded by Eumenes II, king of Pergamon, in the 2nd century BC, Hierapolis was a significant center for its thermal springs, believed to have healing properties. The city flourished during the Roman and Byzantine periods, becoming an important Christian center. Hierapolis boasts well-preserved ruins, including a large theater, a necropolis (ancient cemetery), a temple of Apollo, and the Martyrium of St. Philip. The combination of Pamukkale's unique natural beauty and Hierapolis's historical significance has earned the site a place on the UNESCO World Heritage List.