Everything else Hezekiah did while he was king, including how he made the upper pool and tunnel to bring water into Jerusalem, is written in The History of the Kings of Judah.note[2 Kings 20.20.]
In the tunnel was a brief inscription, written in an old type of the Hebrew alphabeth, of the first meeting, deep underground, of two teams of workers.
... [when the tunnel] was driven through. And this was the way in which it was cut through:
While [the quarrymen were] still [...] axes, each man toward his fellow, and while there were still three cubits to be cut through, [there was heard] the voice of a man calling to his fellow, for there was an overlap in the rock on the right [and on the left]. And when the tunnel was driven through, the quarrymen hewed [the rock], each man towards his fellow, axe against axe; and the water flowed from the spring toward the reservoir for 1,200 cubits, and the height of the rock above the heads of the quarrymen was a hundred cubits.note[Translation W.F. Albright.]
In 701, the Assyrian king Sennacherib laid siege to Jerusalem, but was unable to capture the capital of Judah.