Hezekiah's Aqueduct was a tunnel dug below a hill.
The Assyrians were coming to attack the city and the only source of water, the Spring of Gihon, lay before them at the base of the city.
It was an amazing feat of that age that they dug through solid rock and met in the middle, thus forming an underground aqueduct. The water flowed them from the Spring, which covered over from sight, to the Pool of Siloam, hidden upon the far side of the hill.
Behind the scenes
The aqueduct is composed of 4 screens, each darker than the previous one. The final will be completely dark and Arthur will hit his head and die.
When the player tries to leave Fatima's house before passing the Test of the Symbols, the threshold before her door will open as a trap. Arthur will fall through an underground tunnel and find himself in the aqueduct. 10 Wisdom points are reduced from the score, although the player can walk his way back to Jerusalem and Fatima to continue the game.