A Neolithic Skyscraper
At the archaeological site of Tell es-Sultan, the mound of ancient Jericho, stands a conical stone tower that is 10,000 years old. Built around 8000 BCE during the Pre-Pottery Neolithic A period, the structure rises 8.5 meters (28 feet) from the earth. Its base has a diameter of nearly 9 meters (30 feet), tapering to 7 meters (23 feet) at the top. The walls are approximately 1.5 meters thick and constructed from undressed, or rough-hewn, stones laid without mortar. This construction required a significant communal effort, with one estimate suggesting it took 11,000 working days to complete.
Inside the solid structure, a steep internal staircase of 22 stone steps ascends to the top. This feature is one of the earliest known staircases in the world. The tower was not a standalone object; it was integrated into a large stone wall that enclosed the settlement, which also featured a rock-cut ditch on the exterior. The entire complex is one of the first known examples of urban fortification. British archaeologist Kathleen Kenyon discovered the tower between 1952 and 1958, and her work established its immense age, predating the pyramids of Egypt by more than 5,000 years.
Celestial Clock or Fortress?
The precise function of the Jericho Tower is a subject of scientific debate. Kenyon's initial theory was that the tower and its adjoining wall were fortifications, built to protect the settlement near the 'Ain es-Sultan spring from hostile neighbors or floods. This view has been questioned, as there is little evidence of widespread conflict in the region at the time of its construction.
A more recent hypothesis connects the tower to astronomy. Archaeologists Ran Barkai and Roy Liran proposed that the structure functioned as a kind of solar calendar. Using computer simulations, they demonstrated that on the summer solstice, the shadow of the nearby mountain peak, Quruntul, would have fallen directly on the tower at sunset before enveloping the entire village. The staircase itself is aligned with the sunset on this specific day. This alignment suggests the tower was built to mark the longest day of the year, a significant event for an early agricultural community. It could have been used to structure rituals or to reinforce social hierarchies, with leaders using this astronomical knowledge to organize the community.