In a few places, the Bible mentions about the chiseling of this tunnel (2 Kings 19-20, 2 Chr. 32, Isaiah 36-37). In the wider context, in 705 King Sennacherib from Assyria took reign. In preparation for his southern advance, Hezekiah carved out of the bedrock a 1,720 foot tunnel. The purpose for doing so was to allow the waters from the Gihon Spring (the source of water for the City of David) to flow south to the inside part of the city. So with two team of rock cutters starting at opposite ends, the tunnel was carved.
We even have an inscription (the Siloam Inscription) that tells us how it was precisely done. This inscription was discovered in 1880 and still today is housed on display in the Istanbul Museum. It describes how the the two teams of rock cutters met in the middle of the tunnel. They literally heard each other’s picks and axes until they broke through. Amazing!
The video below is yet another one that features Dr. Ronnie Reich. He is an Israeli archaeologist who excavated over 10 years at the City of David. He shares some interesting perspectives on the tunnel.
Also, a shorter video was produced by the City of David Foundation.