Hezekiah's Tunnel, or the Siloam Tunnel (Hebrew: נִקְבַּת השילוח, Nikbat HaShiloah) is a tunnel that was dug underneath the City of David inJerusalem before 701 BC during the reign of Hezekiah of Judah. The tunnel is mentioned in 2 Kings 20:20 in the Bible. The Bible also tells us that King Hezekiah prepared Jerusalem for an impending siege by the Assyrians, by "blocking the source of the waters of the upper Gihon, and leading them straight down on the west to the City of David" (2 Chronicles 32). The tunnel has been securely dated both by the written inscription found on its wall (Siloam Inscription), and by dating organic matter contained in the original plastering. It is one of the few intact, 8th century BC structures in the world that the public can not only visit, but enter and walk through.
The tunnel, leading from the Gihon Spring to the Pool of Siloam, was designed as an aqueduct to provide Jerusalem with water during an impending siege by the Assyrians, led by Sennacherib. The curving tunnel is 533 m long, and by using a 30 cm (0.6‰) gradient altitude difference between each end, conveyed water along its length from the spring to the pool.
According to the Siloam inscription, the tunnel was excavated by two teams, one starting at each end of the tunnel and then meeting in the middle. The inscription is partly unreadable at present, and may originally have conveyed more information than this. It is clear from the tunnel itself that several directional errors were made during its construction.Recent scholarship has discredited the idea that the tunnel may have been formed by substantially widening a pre-existing natural karst.
The difficult feat of making two teams digging from opposite ends meet far underground is now understood to have been accomplished by directing the two teams from above using sounds generated by hammering on the solid karst through which the tunnelers were digging.
Function and origin
The ancient city of Jerusalem, being on a mountain, is naturally defensible from almost all sides, but suffers from the drawback that its major source of fresh water, the Gihon spring, is on the side of the cliff overlooking the Kidron Valley. This presents a major military weakness as the city walls, if high enough to be defensible, must necessarily leave the Gihon spring outside, thus leaving the city without a fresh water supply in case of siege.
The Bible says that King Hezekiah (c. 8th century BC), fearful that the Assyrians would lay siege to the city, blocked the spring's water outside the city and diverted it through a channel into the then Pool of Siloam. However, it is now known (as of 1997) that the earlier Warren's shaft system had already heavily fortified the Gihon Spring; Warren's shaft is not an aqueduct, and requires those desiring water to travel up and down it themselves - an arrangement that Hezekiah seemingly must have considered inadequate.
In 1899, an ancient channel, also leading from the Gihon Spring to the Siloam Pool area, but by a more direct route, was found. This channel is now known as the Middle Bronze Age channel, on account of its estimated age. Ronny Reich determined that it was constructed around 1800 BC(in the Middle Bronze Age), and thus that the spring's water had already been diverted many centuries before Hezekiah. As originally constructed, it is understood as a 20 feet deep ditch in the ground, covered over by large rock slabs (which were then hidden in the foliage). It is narrower than the tunnel, but can still be walked by a human for most of its length. In addition to the (3 ft high) exit near the Siloam pool, the channel has several small outlets that watered the gardens facing the Kidron Valley. Hezekiah's tunnel was constructed to replace this channel, since a besieging army could fairly easily have discovered and destroyed the Middle Bronze Age Channel.
Hezekiah's tunnel, discovered in 1838 by the American biblical scholar Edward Robinson, can be walked through today from end to end.
The Bible verses relating to Hezekiah's tunnel are these:
"As for the other events of Hezekiah’s reign, all his achievements and how he made the pool and the tunnel by which he brought water into the city, are they not written in the book of the annals of the kings of Judah?" 2 Kings 20:20
"When Hezekiah saw that Sennacherib had come and that he intended to wage war against Jerusalem, he consulted with his officials and military staff about blocking off the water from the springs outside the city, and they helped him. They gathered a large group of people who blocked all the springs and the stream that flowed through the land. 'Why should the kings of Assyria come and find plenty of water?' they said." 2 Chronicles 32:2-4
"It was Hezekiah who blocked the upper outlet of the Gihon spring and channeled the water down to the west side of the City of David. He succeeded in everything he undertook." 2 Chronicles 32:3
Doubts over dating
Excavation work in the tunnel by Ronny Reich of the University of Haifa and Eli Shukron of the Israel Antiquities Authority has cast doubt over the attribution of the tunnel to the reign of Hezekiah.They believe the evidence points to a date several decades earlier, in the last part of the 9th century or early part of the 8th century. They note that the biblical passage connecting Hezekiah to the construction of waterworks doesn't specify a place in the city, and suggest it might refer to waterworks in the Mamilla area.