The descent into ancient Jerusalem’s underground waterworks begins with this flight of iron steps (above), built over the ancient stone steps when the tunnel was recently opened to the public. The stairs lead to a gently inclined tunnel (below). The distant figure in the lower photo is standing at a bend in this tunnel, which curves sharply.

Just around a bend in the horizontal tunnel, a tourist peers down Warren’s Shaft (next photo), which is a natural sinkhole. At bottom, the late archaeologist Yigal Shiloh uses a rope ladder to climb up the 37-foot shaft, demonstrating how, according to some scholars, David’s general Joab may have entered the city through its water system.

But according to authors Ronny Reich and Eli Shukron, the horizontal tunnel, as originally cut, did not dip down to the top of Warren’s Shaft. Instead, the floor of the tunnel at this point was aligned with what looks like a horizontal crack visible halfway up the rock walls in the center photo, which marks the boundary between the softer, upper rock and the harder, lower rock. Located beneath several feet of hard stone, the top of Warren’s Shaft was neither visible nor accessible at that time. Probably no one even knew it existed.

Moreover, the original tunnel—running about 5 feet above the entrance to Warren’s Shaft—continued around the bend in the center photo—eventually leading through a cave to the pool beside the Gihon Spring.a

Only in the eighth century B.C.E. (long after the time of David) did tunnelers deepening the tunnel accidentally strike the top of Warren’s Shaft, creating the system as it appears today.