Hezekiah's Tunnel

In 1830, a hexagonal clay prism,

 known as the  "Taylor Prism,"

 was discovered among the ruins of Ninevah. 

It tells us that Sennacherib, the king of Assyria

 in the Eighth Century BC, 

had Hezekiah trapped in Jerusalem
 like a "bird in a cage." 

Hezekiah and his engineers refortified 
the city walls and carved a 1, 720 foot tunnel
 out of solid bedrock to bring
 the ever-flowing waters of the Gihon spring
 into the inner sections of the city.
The only spring in Jerusalem, 
the Gihon is a siphonic, karstic
spring, and its name means "gushing". 
It is thought that the Gihon
 could have supported a population of 2500.
,

1 Kings 1:38          2 Kings 20       2 Chronicles 29-32

The Gihon Spring was Jerusalem's main water source

 from the city's earliest days. 

However, the spring's location 

near the bottom of the eastern slope

 forced the city's builders to leave it outside 

the city walls and to create a protected passageway

 that led to the water source.
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 522 meters long.

According to the Siloam inscription, 
the tunnel was excavated by two teams, 
one starting at each end of the the tunnel
 and then meeting in the middle. 
With trail and some errors, 
it is thought that the teams digging
 were directed from above using sounds
 generated by hammering on the solid karst (limestone)
 through which they were digging.

Hezekiah's Tunnel was discovered by American explorer 

Edward Robinson in 1838. 

In the 1860's another explorer named Charles Warren

 is credited for the discovery of a 52 foot vertical shaft

 that descends to the level of the water tunnel.

You can touch the pick marks
 on the walls of the tunnel.

fortified walls and ceilings-
notice arch and the
very large blocks.
There are some wonderful explanations and diagrams
 at this following site
 to give even more info about this tunnel.
Hezekiah_Tunnel