The world famous Pamukkula travertines, also called ''the Cotton Castle'' are located on the Southern banks of the ancient city of Hierapolis. These travertines, a natural phenomenon, were formed over thousands years as the cooling water solidified the further it got from its calcareous hot water source. Naturally abundant in radon gas, the hot springs of Pamukkale have healing properties. Pamukkale and Hierapolis were both granted World Heritage status in 1988.
Hierapolis is locates 24 km from Denizli and was founded by the Bergama King Eumenes II in 190 B.C. The city was named after ''Hiera' who was the beautiful wife of the legendary hero Telefos and it also means ''Holy City''. The ancient city of Hierapolis, the original site of Pamukkale, was known as the Holly City in archeological literature, because of the abundance of temples and other religious structures in the area. The city has traces of the Hellenistic period and was seized by the Romans, together with Bergama in 133 B.C. It was completely destroyed by a violent earthquake in 17 B.C. in the time of the Roman Emperor Tiberius. The city was the rebuilt in the Roman style and lived its golden age under the reign of the Roman Emperor Septemius Severus during the 2nd and 3rd centuries A.D., becoming a summer retreat for the Roman Empire elites.
The Hierapolis thermal pools, necropolis, streets, agora, city doors, gymnasium, antars, lonian columns bridges and churches are fascinating to explore and its theatre , with a capacity of 9.000, is a stunning feat of architecture.
Laodikeia is situated in an excellent geographical location on the south side of the Lycus Rives, 6 km North of Denizli. The city was called ''Laodikeia on the edge of the Lycus'' in ancient sources. According to other ancient sources, the city was founded by Antiochos II in 263-261 BC and named after Antiochos'' wife.
Laodikeia was the most famous and influential city in the 1st century B.C. The remains of the city are dated from this era. The Romans made the city the center of Kybira's conventus (Golfhisar-Horzum) because of the geographical setting. A series of coins were minted in Laodikeia during the reign of Caracalla. Many monumental buildings were also built in Laodikeia through donations from the local inhabitants. One of the famous seven churches mentioned the Bible in Revelations was located in Laodicea, which shows that Christianity was important here. Unfortunately, the city was destroyed by the earthquake.