2 Kings 18:17

And the king of Assyria, intending to take Jerusalem in spite of the heavy ransom-money which he had received, sent Tartan and Rabsaris and Rabshakeh, three of his highest civil and military officers, from Lachish, where his advance was still checked, to King Hezekiah with a great host against Jerusalem. And they went up and came to Jerusalem, they appeared before the city with their army. And when they were come up, they came and stood by the conduit of the upper pool, which is in the highway of the fuller's field. The upper pool, or reservoir, of the city of Jerusalem was that of Gihon, 2 Chronicles 32:30; 1 Kings 1:33; Isaiah 7:3, toward the west. Hezekiah had filled up the surface canal, which, in case of a siege, could easily have been dammed by the enemies, and had constructed a tunnel which brought the water to a reservoir inside the walls, 2 Kings 20:20. So the Assyrian officers stood on an elevation near the western wall of the city.