The Babylonians are said to have built a tunnel under the Euphrates River in circa 2180 B.C.E. using what is now known as the cut-and-cover method. The river was diverted, a wide trench was dug across the riverbed, and a brick tube was constructed in the trench. The riverbed was filled in over the tube and the river allowed to resume its normal course. However, there is no firm proof of this tunnel's existence, so we need to look to the more recent past. Many tombs of the Egyptian New Kingdom pharaohs buried between 1481 and 1069 B.C.E. in the Valley of the Kings were approached by tunnels dug in the solid rock, but these are as much entrances as tunnels.
The first real tunnel—that is, one that was dug through solid rock from both ends, to meet in the middle—was Hezekiah's Tunnel (the Siloam Tunnel) in Jerusalem. This tunnel was dug through solid rock to act as an aqueduct and bring water into the city during an imminent siege by the Assyrians. The two opposing teams of excavators made several directional errors during construction, resulting in a 1,757-foot (535 m) curving tunnel that gently slopes from the Gihon Spring down to the Pool of Siloam by the city walls; as a straight distance, it covers only 1,104 feet (309m). More famously, and more accurately, the Greek engineer Eupalinos dug a straight tunnel through Mount Kastro on Samos to supply its capital with water. The 3,399-foot (1,036 m) tunnel, dug sometime between 550 and 530 B.C.E., was perfectly constructed: the two teams of excavators met in the middle with a vertical difference between the two tunnels of only 1.5 inches (3 cm).
