This is not for the faint hearted. Hezekiah's Tunnel is a narrow passageway which was built in 701 BC under the Ophel in the city of Jerusalem. Connecting Pool of Siloam and Gihon Spring, the tunnel is nearly 530 m long. It was used as aqueduct for water supply between the two destinations. Today, it is a major tourist destination. They can walk the narrow tunnel, not wide enough for even two to pass abreast. Carry along a bright flashlight as there is no way for natural light, naturally.