Zion (Hebrew: צִיּוֹן Ṣīyyōn, LXX Σιών, also variously transliterated Sion, Tzion, Tsion, Tsiyyon) is a placename in the Hebrew Bible used as a synonym for Jerusalem as well as for the Land of Israel as a whole (see Names of Jerusalem).
The name is found in 2 Samuel (5:7), one of the books of the Hebrew Bible dated to before or close to the mid-6th century BC. It originally referred to a specific hill in Jerusalem (Mount Zion), located to the south of Mount Moriah (the Temple Mount). According to the narrative of 2 Samuel 5, Mount Zion held the Jebusite fortress of the same name that was conquered by David and was renamed the City of David. That specific hill ("mount") is one of the many squat hills that form Jerusalem, which also includes Mount Moriah (the Temple Mount), the Mount of Olives, etc. Over many centuries, until as recently as the Ottoman era, the city walls of Jerusalem were rebuilt many times in new locations, so that the particular hill known as Mount Zion is no longer inside the city wall, but its location is now just outside the portion of the Old City wall forming the southern boundary of the Jewish Quarter of the current Old City. Most of the original City of David itself is thus also outside the current city wall.
The term Tzion came to designate the area of Davidic Jerusalem where the fortress stood, and was used as well as synecdoche for the entire city of Jerusalem; and later, when Solomon's Temple was built on the adjacent Mount Moriah (which, as a result, came to be known as the Temple Mount) the meanings of the term Tzion were further extended by synecdoche to the additional meanings of the Temple itself, the hill upon which the Temple stood, the entire city of Jerusalem, the entire biblical Land of Israel, and "the World to Come", the Jewish understanding of the afterlife.