page_title: Hierapolis
section_title: Ploutonion
hierarchical_section_title: Hierapolis / Significant structures / Ploutonion
context_page_description: Hierapolis was an ancient Greek city located on hot springs in classical 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. The site has the Tomb of Philip the Apostle.
  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, which bears a relief depicting the earliest known example of a crank and rod mechanism.
  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, including the bath, library, and gymnasium.
context_section_description: Next to this temple and within the sacred area is the oldest local sanctuary, Pluto's Gate, a ploutonion (Ancient Greek: Πλουτώνειον) or plutonium, which here means a shrine to the Greek god Pluto. This plutonion was described by several ancient writers, including Strabo, Cassius Dio, and Damascius. It is a small cave just large enough for one person to enter through a fenced entrance, beyond which stairs go down and from which emerges suffocating carbon dioxide gas caused by subterranean geologic activity. Behind the 3 square metres (32 sq ft) roofed chamber is a deep cleft in the rock, through which fast-flowing hot water passes while releasing a sharp-smelling gas.
  During the early years of the town, castrated priests of Cybele descended into the plutonion, crawling over the floor to pockets of oxygen or holding their breath. Carbon dioxide is heavier than air and so tends to settle in hollows. The priests would then come up to show that they were miraculously immune to the gas and infused with divine protection.
  An enclosed area of 2,000 square metres (22,000 sq ft) stood in front of the entrance. It was covered by a thick layer of suffocating gas, killing anyone who dared to enter it. The priests sold birds and other animals to the visitors, so that they could try out how deadly this enclosed area was. Visitors could (for a fee) ask questions of Pluto's oracle. This provided a considerable source of income for the temple. The entrance to the plutonion was walled off during the Christian times and has just been recently unearthed.
caption: The Nymphaeum
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