Water tunnel that was carved under the City of David in Jerusalem in ancient times. Its popular name is due to the most common hypothesis of its origin, namely, that it dates from the reign of Hezekiah. The tunnel leads from the Gihon Spring to the Pool of Siloam. If indeed built under Hezekiah, it dates to a time when Jerusalem was preparing for an impending siege by the Assyrians, led by Sennacherib. Since the Gihon Spring was already protected by a massive tower and was included in the city’s defensive wall system, Jerusalem seems to have been supplied with enough water in case of siege even without this tunnel. The curving tunnel is 533 m., According to the Siloam inscription, the tunnel was excavated by two teams, one starting at each end of the tunnel and then meeting in the middle.