2,800-Year-Old Mega-Dam Unearthed in Jerusalem City of David

Archaeologists in Jerusalem have uncovered the largest and earliest-known dam in ancient Israel, dating back approximately 2,800 years to the reign of Kings Joash or Amaziah of Judah. This massive dam, part of the Siloam Pool water system, was strategically built to manage extreme climate conditions by controlling both drought and flash floods, collecting runoff from the Tyropoeon Valley and the Gihon Spring. Carbon dating of organic materials in the dam's mortar provided a precise construction timeframe between 805 and 795 BCE, coinciding with a period of unusual aridity and violent rains. The discovery reveals the Kingdom of Judah's advanced engineering capabilities and supports biblical accounts of Jerusalem as a powerful and sophisticated city earlier than previously believed. The dam’s remarkable size—about 12 meters high, 8 meters wide, and at least 21 meters long—demonstrates a complex urban water management system designed to secure reliable water resources amid environmental challenges. This finding, published in the Proceedings of the National Academy of Sciences, reshapes understanding of Jerusalem’s development during the First Temple period.