View of the interior of Hezekiah’s Tunnel close to the Gihon Spring.
Hezekiah's (715 B.C. - 686 B.C.) Tunnel was built to transport water from the Gihon Spring to the Pool of Siloam. It is 1760 ft. [533 m.] in length. At the beginning the ceiling is very low (5 ft. [1.5 m.]), at the Siloam end quite high (16 ft. [5 m.]). It is "S–shaped" and it seems that it was built to bring water from the east side of the city to an area inside the wall closer to the newly inhabited western portion of the city and possibly to help ensure a constant supply of water to the inhabitants of Jerusalem during Sennacherib’s siege (701 B.C.).
Its construction is noted in the Bible (2 Kings 20:20; 2 Chron 32:2–4, 30) and on an ancient five line Hebrew inscription that was found near its south end.
In the image note the water is about knee deep. At other times it has been chest high – due to damming and silting.