Warren's Shaft is an archaeological feature in Jerusalem found by Charles Warren in the late 19th century. It runs from within the old city to a spot near the Gihon Spring, and after its 19th century discovery was thought to have been the centrepiece of the city's early water supply system, since it would have enabled the city's occupants to safely reach fresh water (which was otherwise unavailable within the city) even if the city itself was besieged. The narrow and tall shaft was demonstrated to be traversable when a member of Warren's excavation climbed from top to base. Since in the Books of Samuel it states that David conquered Jerusalem from its prior inhabitants due to Joab sneaking up a similar water shaft and launching a surprise attack on the city from inside, it was long thought