<P> The length of the walls is 4,018 meters (2.4966 mi), their average height is 12 meters (39.37 feet) and the average thickness is 2.5 meters (8.2 feet). The walls contain 34 watchtowers and seven main gates open for traffic, with two minor gates reopened by archaeologists . </P> <P> In 1981, the Jerusalem walls were added, along with the Old City of Jerusalem, to the UNESCO World Heritage Site List . </P> <P> The city of Jerusalem has been surrounded by walls for its defense since ancient times . In the Middle Bronze Age, a period also known in biblical terms as the era of the Patriarchs, a city named Jebus was built on the southeastern hill of Jerusalem, relatively small (50,000 square meters) but well fortified . Remains of its walls are located above the Siloam Tunnel . The identification of Jebus with Jerusalem has been disputed, principally by Niels Peter Lemche . Supporting his case, every non-biblical mention of Jerusalem found in the ancient Near East refers to the city as' Jerusalem' . An example of these records are the Amarna letters which are dated to the 14th century BCE, several of which were written by the chieftain of Jerusalem Abdi - Heba and call Jerusalem either Urusalim (URU ú - ru - sa - lim) or Urušalim (URU ú - ru - ša - lim) (1330s BCE). Also in the Amarna letters, it is called Beth - Shalem, the house of Shalem . </P> <P> According to Jewish tradition, as expressed in the Tanakh, Jerusalem remained a Jebusite city until the rise of David, who conquered Jebus, renamed it City of David and started expanding it . His city was still located on the low southeastern hill, outside today's Old City area . Solomon, David's son, built the First Temple on the hilltop rising right above the city he had inherited, the Temple Mount, and then extended the city walls in order to protect the temple . </P>

When was the first wall of jerusalem built
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