jericho_wall_color2

The wall of Jericho, also referred to as Sultanian[citation needed] is a Pre-Pottery Neolithic A (PPNA) defensive wall dated to approximately 8000 BC. It is thought to be the first city wall ever built. It surrounded and protected a Neolithic settlement which contained anywhere from 2000 to 3000 people. The wall was complemented by a stone tower built into it. The tower had stairways and is thought to have reached a height of ten meters. The wall is thought to have been built in order to prevent floods but the height of the wall (approximately 5 feet (1.5 m) thick and 12 to 17 feet (5.2 m) high) as well as that of the tower suggests a defensive purpose as well. Furthermore, the construction of such a project implies some sort of social organization, division of labour, and classes.

The town of Jericho, which was about six acres (2.5 hectares) in size, preceded the wall by about 500 years. In fact, evidence suggests that construction started prior to the agricultural revolution. The town contained round mud-brick houses, yet no street planning. Despite the existence of the wall and tower, Jericho is still a proto-city, much like Çatalhöyük.

http://en.wikipedia.org/wiki/PPNA_Wall_of_Jericho