Hierapolis was an ancient city located on hot springs in Phrygia in southwestern Anatolia. Its ruins are adjacent to modern Pamukkale in Turkey and currently comprise an archaeological museum designated as a UNESCO World Heritage Site. In the first century it was part of the tri-city area of Laodicea, Colossae, and Hierapolis. The name means “a sacred city”; it was believed by the ancients to have been founded by the god Apollo. Hierapolis was famed for its springs, whose vapours were associated with Pluto, god of the underworld. The hot springs have been used as a spa since the 2nd century BC, with many patrons retiring or dying there. The large necropolis is filled with sarcophagi, most famously that of Marcus Aurelius Ammianos.