|Easton's Bible Dictionary|
Sacred city, a city of Phrygia, where was a Christian church under the care of Epaphras (Colossians 4:12, 13). This church was founded at the same time as that of Colosse. It now bears the name of Pambuk-Kalek, i.e., "Cotton Castle", from the white appearance of the cliffs at the base of which the ruins are found.
Int. Standard Bible Encyclopedia
he-er-ap'-o-lis (Hierapolis, "sacred city"): As the name implies, Hierapolis was a holy city. It was situated 6 miles from Laodicea and twice that distance from Colosse, on the road from Sardis to Apamea. Though its history is not well known, it seems to have been of Lydian origin, and once bore the name of Kydrara. The Phrygian god Sabazios was worshipped there under the name Echidma, and represented by the symbol of the serpent. Other local deities were Leto and her son Lairbenos. Though called the holy city, Hierapolis was peculiarly regarded as the stronghold of Satan, for there was a Plutonium, or a hole reaching far down into the earth, from which there issued a vapor, even poisoning the birds flying above. It is supposed that upon a stool, deep in the Plutonium, a priest or priestess sat, and, when under the influence of the vapor, uttered prophecies valuable to those who sought them. Though a stronghold of Satan, Hierapolis early became a Christian city, for, according to Colossians 4:13, the only place where it is mentioned in the New Testament, a church was founded there through the influence of Paul while he was at Ephesus. Tradition claims that Philip was the first evangelist to preach there, and it also claims that he and his two unmarried daughters were buried there; a third who was married, was buried at Ephesus. Several of the early Christians suffered martyrdom at Hierapolis, yet Christianity flourished, other churches were built, and during the 4th century the Christians filled the Plutonium with stones, thus giving evidence that the paganism had been entirely supplanted by the church. During the Roman period, Justinian made the city a metropolis, and it continued to exist into the Middle Ages. In the year 1190 Frederick Barbarossa fought with the Byzantines there.
The modern town is called Pambuk Kalessi, or cotton castle, not because cotton is raised in the vicinity, but because of the white deposit from the water of the calcareous springs. The springs were famous in ancient times because they were supposed to possess Divine powers. The water is tepid, impregnated with alum, but pleasant to the taste. It was used by the ancients for dyeing and medicinal purposes. The deposit of pure white brought up by the water from the springs has heaped itself over the surrounding buildings, nearly burying them, and stalactite formations, resembling icicles, hang from the ruins. The ruins, which are extensive, stand on a terrace, commanding an extensive view, and though they are partly covered by the deposit, one may still trace the city walls, the temple, several churches, the triumphal arch, the gymnasium and baths, and the most perfect theater in Asia Minor. Outside the walls are many tombs.
E. J. Banks
Hierapolis (1 Occurrence)
Colossians 4:13 For I testify about him, that he has great zeal for you, and for those in Laodicea, and for those in Hierapolis. (WEB KJV WEY ASV BBE DBY WBS YLT NAS NIV)