20:20 a pool, and a conduit. The conduit and pool were constructed by King Hezekiah in anticipation of the coming Assyrian siege, in order to assure a water supply for Jerusalem during the siege. The tunnel was rediscovered in the 19^th century, cut in solid rock under Mt. Zion and the city walls, extending 1780 feet from Gihon Spring to the pool of Siloam. On the tunnel wall, near its exit, was found a Hebrew inscription commemorating the completion of the tunnel, and noting the surveying skill of its engineers, who constructed it simultaneously from both ends, meeting in the center. The Old Testament date of the tunnel, corresponding to Hezekiah’s time, has recently been confirmed by radiocarbon dating.