Hezekiah's Tunnel

A tunnel was constructed from the spring at Gihon - what is now called the Virgin's Fountain - under the city walls and through the rock to the southern end of the city of Jerusalem, to the pool of Siloam. This would be a difficult feat in these days of sophisticated surveying and measuring equipment. It was even more remarkable for the times of Hezekiah, because the impending invasion meant there was very little time and gangs of workmen had to start from either end. When the tunnel was complete, the spring outside the city was blocked up and the water flowed into the city.

The second book of Chronicles records:

"And when Hezekiah saw that Sennacherib was come, and that he was purposed to fight against Jerusalem, he took counsel with his princes and his mighty men to stop the waters of the fountains which were without the city: and they did help him. So there was gathered much people together, who stopped all the fountains and the brook that ran through the midst of the land, saying, Why should the kings of Assyria come, and find much water?" (2 Chronicles 32:2-4)
"And the rest of the acts of Hezekiah, and all his might, and how he made a pool, and a conduit, 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)