On

On (Egyptian: Iunu; Greek: Heliopolis, city of the sun) was the principal center of sun-worship in ancient Egypt, located in the Nile Delta approximately ten miles northeast of modern Cairo. It was home to the great temple of Ra-Atum-Khepri and its famous obelisks, and its high priest was among the most powerful religious officials in Egypt. The biblical patriarch Joseph married Asenath, the daughter of Potiphera, priest of On (Genesis 41:45, 50), cementing his integration into Egyptian elite society.

The prophets of Israel directed oracles against On as a symbol of Egyptian idolatry: Jeremiah 43:13 predicts that Nebuchadnezzar will break the obelisks of Beth-shemesh (House of the Sun, i.e., Heliopolis) and burn the temples of Egypt's gods. Ezekiel 30:17 prophesies that the young men of On and of Pi-beseth will fall by the sword. Isaiah 19:18 speaks mysteriously of a City of the Sun that will one day speak the language of Canaan and swear allegiance to the LORD.