Three water systems have sprung from the Gihon Spring at various times in Jerusalem’s history. The oldest, shown in yellow, is known as Warren’s Shaft after it modern discoverer, Captain Charles Warren. Probably dating to at least the eleventh century B.C.E., it gave the city protected access to the water of the spring, which lay outside the city wall. Because the Gihon Spring lies low on the slope, the Jebusites (and the Israelites later) could not include it within their city wall. Had the walls been built low on the slope, the city would have been exposed to attack from the high slope across the Kidron Valley.
The Siloam channel, shown in red, was built next. This aqueduct irrigated adjacent fields through openings in the channel wall. The channel’s position outside the city wall indicates that it served during times of peace. Archaeologists suggest that the Siloam channel may date to Solomon’s time (965–928 B.C.E.).
The third water system, Hezekiah’s tunnel, appears in brown. Threatened with siege by the Assyrian forces of Sennacherib in 701 B.C.E., the Judahite king Hezekiah ordered the construction of the tunnel to divert water from the Gihon Spring, outside his city walls, to the Siloam Pool, safely within the walls. Hezekiah’s idea succeeded (2 Kings 20:20 and 2 Chronicles 32:30), and Sennacherib failed to capture Jerusalem.