Subterranean Waterworks of Biblical Jerusalem: Adaptation of a Karst System

Ancient Jerusalem has long been known to possess a system of subterranean waterworks by which the spring of Gihon, which issues outside the walls, could be approached from within the city, and its waters diverted to an intramural pool. Most scholars regarded these waterworks as man-made, but the techniques of underground orientation and ventilation employed by the builders, as well as the numerous anomalies and ostensible mistakes in design, mystified investigators. Geological investigation has revealed the waterworks to be part of a well-developed karst system, a network of natural dissolution channels and shafts, in the limestone and dolomite underlying the city. Thus, it was not through primary planning but by means of skillful adaptation of these pre-existing natural features that the city was ensured of a dependable water supply during both war and peace. Likewise, knowledge of the subterranean access may have played a role in David's capture of the Jebusite city.