An undying thirst for a safe water supply inspired the construction of ancient Jerusalem’s water system beside the Gihon Spring, the city’s only natural water source, located low on the eastern slope of the City of David. Three years ago archaeologists Ronny Reich and Eli Shukron discovered the remains of a massive complex of towers, built in the Middle Bronze Age II (18th to 17th century B.C.), that protected the spring and its waters. The system, as shown in the plan, included the Spring Tower, located directly above the Gihon Spring (excavated remains from the Middle Bronze Age appear in deep red; reconstructed remains are in pink). Channel II shunted water south from the spring. The top of the channel was sealed with huge boulders, dropped from above and trapped by the channel’s slightly convex walls. A subsidiary tunnel (Tunnel III) deflected the water into a 22- by 10-foot pool, which was protected by at least one tower.