Pictured here is "Warren's shaft", a water pipe which was vital for whoever controlled Jerusalem, since it was the source of Jerusalem's water. When King David brought his army to conquer Jerusalem he said whoever would capture the "tzinor" or water pipe, as well as destroy the two idols in the city (called the 'blind and lame') would be appointed his chief of staff (Samuel II 5:8) - such was the importance of the "tzinor". Warren's shaft carries water from outside the city walls (from the Gihon spring) to within the walls of Jerusalem.