HELIOPOLIS (Gr., meaning "city of the sun"; Egyptian, Iunu; Heb., On), ancient city of lower Egypt situated about six miles N. of Cairo on the site of the modern village of El Matariyah. From earliest times Heliopolis was the cult center for the worship of the sun god, usually in his manifestation as Re, but also as Re-Horakhty and Atum. Although some form of sun worship existed from the beginning of recorded Egyptian history, it was not until the Fifth Dynasty (c. 2480–2340 B.C.E.) that the Helipolitan cult of Re achieved its preeminent position in the cosmogony of the Egyptians, a position which it retained well into the third century B.C.E.
Heliopolis is specifically mentioned four times in the Bible: Genesis 41:45, 45:50 and 46:20, where Joseph is given as wife Asenath, the daughter of Poti-Phera, the priest of On (who must have been the high priest of Re of Heliopolis); and Ezekiel 30:17, where the prophet foretells the destruction of Egypt by the hand of Nebuchadnezzar, the Babylonian king, and mentions Heliopolis among the great cities to be destroyed. The prediction of the destruction of Beth-Shemesh, "the House of the Sungod," in Jeremiah 43:13 is also probably a reference to Heliopolis. Another possible reference to the city is Isaiah 19:18, where, in view of the Egyptian context of the passage, the reading ir ha-ḥeres, or "city of the sun," as attested by Symmachus and Vulgate, is preferred by many scholars to the present masoretic text ir ha-heres, or "city of destruction."