Mount Zion is a hill in Jerusalem, located just outside the walls of the Old City. The term Mount Zion has been used in the Hebrew Bible first for the City of David (2 Samuel 5:7, 1 Chronicles 11:5; 1 Kings 8:1, 2 Chronicles 5:2) and later for the Temple Mount, but its meaning has shifted and it is now used as the name of ancient Jerusalem's Western Hill.
In the second half of the First Temple period, the city expanded westward and its defensive walls were extended to include the entire Western Hill behind them. Nebuchadnezzar II destroyed the city almost completely around 586 BCE, severing the continuity of historical memory. A long period of rebuilding followed, ending with Jerusalem's second total destruction at the hands of the Romans in 70 CE. Josephus, the first-century CE historian who knew the city as it was before this second catastrophic event, identified Mount Zion as being the Western Hill, separated from the lower, Eastern Hill, by what he calls the "Tyropoeon Valley". It must however be said that Josephus never used the name "Mount Zion" in any of his writings, but described the "Citadel" of King David as being situated on the higher and longer hill, thus pointing at the Western Hill as what the Bible calls Mount Zion.