Jerusalem's water source — a karst spring in the Kidron valley immediately below the eastern ridge of the old city, and the reason a city stands there at all. Solomon is anointed here (1 Kings 1:33, 38, 45) in full public earshot, while Adonijah's rival feast is held out of sight downstream at En Rogel: the geography is the politics. Hezekiah later cut a 533-metre tunnel through solid rock to bring its water inside the walls ahead of the Assyrian siege — the tunnel is still walkable, and the inscription its diggers left describing the moment the two teams met is one of the most remarkable objects from the Old Testament world. ⚠ Not to be confused with the Gihon of Genesis 2:13, one of the four rivers of Eden, which is a different name entirely.