Hierapolis (Greek: Ἱεράπολις 'sacred city') was an ancient Greco-Roman city in Phrygia located on hot springs in southwest Anatolia. Its ruins are adjacent to modern Pamukkale, Turkey.

Hierapolis is a UNESCO World Heritage Site. The hot springs there have been used as a spa since the 2nd century BCE, and people came to soothe their ailments, with many of them retiring or dying here. The large necropolis is filled with sarcophagi, including the Sarcophagus of Marcus Aurelius Ammianos.

The great baths were constructed with huge stone blocks without the use of cement, and consisted of various closed or open sections linked together. There are deep niches in the inner section of the bath, library, gymnasium and other closed or open locations. The complex, which was constructed in the 2nd century BCE, constitutes a good example of vault type architecture. The complex is now an archaeological museum.