Biblical accounts of the construction of an ancient underground tunnel below Jerusalem have been verified by dating the material lining its walls. The books of Kings and Chronicles report that the Siloam tunnel was built by King Hezekiah, ruler of Judea 2700 years ago. Its aim was to provide a secret source of drinking water should the city face a siege by Assyrian assailants. Even today, the tunnel delivers water from the Gihon Spring to the Siloam Pool, 500 metres away. Some scholars have questioned the biblical account, suggesting that the tunnel, which is up to 30 metres below ground,...