Megiddo—The water gallery is a narrow passage made of well-dressed ashlar stones. It is just over three feet wide and up to six feet tall and originally was roofed. The gallery started inside the city, then cut through the 10th century B.C. Solomonic casemate wall, and ended at a point above the spring outside the city wall on the southwest slope of the mound. From there, stairs, which were probably hidden with a covering of wood and earth, linked the gallery to the spring chamber entrance.
In the 9th century B.C. the Solomonic gallery was blocked and covered over by a solid “inset-offset” wall—probably at the same time that the shaft-and-tunnel water system was engineered.