The Gihon SpringThe Gates Of Old Jerusalem) of the ancient city (not to be confused with the Gihon River of Eden i.e. "2:13 And the name of the second river is Gihon: the same is it that compasseth the whole land of Ethiopia" (Genesis 2:13 KJV).
"Hezekiah also stopped the upper watercourse of Gihon and brought it straight down to the west side of the city of David"
King David had his son Solomon declared king of The United Kingdom, while David was still living, due to an attempt by one of David's other sons, Adonijah (1 Kings 1:1-27), to seize the throne. Solomon was crowned at Gihon according to David's instructions: "1:33 The king also said unto them, Take with you the servants of your lord, and cause Solomon my son to ride upon mine own mule, and bring him down to Gihon: 1:34 And let Zadok the priest and Nathan the prophet anoint him there king over Israel: and blow ye with the trumpet, and say, God save king Solomon" (1 Kings 1:33-34 KJV).
"1:32 And king David said, Call me Zadok the priest, and Nathan The Prophet, and Benaiah the son of Jehoiada. And they came before the king. 1:33 The king also said unto them, Take with you the servants of your lord, and cause Solomon my son to ride upon mine own mule, and bring him down to Gihon: 1:34 And let Zadok the priest and Nathan the prophet anoint him there king over Israel: and blow ye with the trumpet, and say, God save king Solomon. 1:35 Then ye shall come up after him, that he may come and sit upon my throne; for he shall be king in my stead: and I have appointed him to be ruler over Israel and over Judah.
When the Assyrians (see Ancient Empires - Assyria) threatened The Southern Kingdom of Judah (the Assyrians had already conquered and taken into exile The Northern Kingdom of Israel; see also The Galilee Captivity), King Hezekiah of Judah "stopped the upper watercourse of Gihon, and brought it straight down to the west side of the city of David" (2 Chronicles 32:30 KJV) to prevent the invaders from having an easy water supply (and to keep them from cutting off the city's water supply during a siege).
"32:1 After these things, and the establishment thereof, Sennacherib king of Assyria came, and entered into Judah, and encamped against the fenced cities, and thought to win them for himself. 32:2 And when Hezekiah saw that Sennacherib was come, and that he was purposed to fight against Jerusalem, 32:3 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. 32:4 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? 32:5 Also he strengthened himself, and built up all the wall that was broken, and raised it up to the towers, and another wall without, and repaired Millo in the city of David, and made darts and shields in abundance." (2 Chronicles 32:1-5 KJV)
Hezekiah's diverting the waters of Gihon turned out to be unnecessary. The Assyrian king Sennacherib brought about his army's defeat when he blasphemed The Lord (see The Day Sennacherib Challenged God).
"32:21 And the LORD sent an angel, which cut off all the mighty men of valour, and the leaders and captains in the camp of the king of Assyria. So he returned with shame of face to his own land. And when he was come into the house of his god, they that came forth of his own bowels slew him there with the sword. 32:22 Thus the LORD saved Hezekiah and the inhabitants of Jerusalem from the hand of Sennacherib the king of Assyria, and from the hand of all other, and guided them on every side. 32:23 And many brought gifts unto the LORD to Jerusalem, and presents to Hezekiah king of Judah [see Kings of Israel and Judah]: so that he was magnified in the sight of all nations from thenceforth.
Fact Finder: Where was "the city of David"?