This entrance to Hezekiah's Tunnel is beneath the City of David, which is located just south of the Temple Mount's southeast corner. Al Aqsa Mosque is directly north of the tunnel's entrance, which is about 300 yards southeast of Old Jerusalem's Dung Gate.
What is Hezekiah's Tunnel?
It is the 8th century BC tunnel that King Hezekiah of Judah ordered dug to both secure Jerusalem's water supply and deny water to the Assyrian king Sennacherib's army that was about to lay siege to Jerusalem. Until Hezekiah's Tunnel was completed, water from Gihon Spring, Jerusalem's fresh water source, flowed into the Kidron Valley just east of the city. Hezekiah's Tunnel diverted Gihon Spring's water to the Pool of Siloam inside Jerusalem (the ancient City of David was situated downhill from the present "Old Jerusalem") so that it supplies water to its residents and lets none of it flow to the besieging enemy outside.
Hezekiah's Tunnel is 1,749 feet (533 meters) long, and a mere 50 centimeter difference in altitude allows the water to flow (below) from Gihon Spring 'down' to the Pool of Siloam.
Hezekiah's Tunnel was excavated using pickaxes, mostly from the Gihon Spring side but also from the side of the Pool of Siloam. The place where the two groups of excavators met, about 19 feet from the Pool of Siloam, is marked by the Shiloah Inscription (below) that commemorates their engineering feat.**
The original Shiloah Inscription was discovered in 1880 during the Ottoman era and chiseled out. The inscription above is at the original location but a copy of the original, which today is on display at the Istanbul Archaeology Museum in Turkey.
Travel Tip
Hezekiah's Tunnel can be visited by those who are physically fit and prepared.
In its initial stretch, the water is cold, up to 3 feet deep, and the current is
strong. After the initial stretch, the current slows, the water is calf-deep and
its cold temperature feels refreshing. The long tunnel is
completely dark, very narrow, and its ceiling is low. Those in shape
and not claustrophobic should wear bathing shorts, sturdy water shoes, and
either bring a flashlight or tightly grip illuminated mobile phones, lest
they hit both water and rock.
Those who are claustrophobic, not in shape or unprepared to get wet can take the Canaanite Tunnel (right), which was excavated by the Canaanites a thousand years before Hezekiah's Tunnel to channel Gihon Spring's water through several openings to their crop fields in the Kidron Valley. One of the Canaanite Tunnel's routes also connects Gihon Spring to the Pool of Siloam. This "dry" tunnel is somewhat steeper but also shorter, wider, has lights and more head room but no water, so it is less physically demanding.
For more Biblical archaeology, see Golgotha, Jesus' Tomb and Capernaum.
* Now the rest of the acts of Hezekiah - all his might, and how he made a pool and a tunnel and brought water into the city - are they not written in the book of the chronicles of the kings of Judah? (2 Kings 20:20)
** English translation of the Shiloah Inscription: "(Behold) the excavation. Now this is the history of the breaking through. While the workmen were still lifting up the pickaxe, each toward his neighbor, and while three cubits yet remained to (cut through, each heard) the voice of the other calling to his neighbor, for there was an excess in the rock on the right... And on the day of the breaking through, the excavators struck, each to meet the other, pickaxe against pickaxe; and there flowed the water from the spring to the pool over (a space of) one thousand and two hundred cubits. And ... of a cubit was the height of the rock above the heads of the excavators."