The Tunnel of Eupalinos

Digging tunnels is probably among the most toughest engineering projects the ancient people undertook, because it required mastering several sophisticated fields of science including architecture, geodesy, hydraulics, and geology. This makes ancient tunnels fascinating subjects for study. The Tunnel of Eupalinos, on the Greek island of Samos, is one such example. Built in the 6th century BC, and first described by Herodotus, the Tunnel of Eupalinos was a major engineering milestone because it is one of the earliest known tunnels that was dug from both ends. Using only picks, chisels and hammers, and relying on simple laws of geometry and trigonometry, these ancient engineers accomplished a nearly impossible feat—meeting beneath a hill more than two hundred meters tall and nearly half a kilometer from either end. Photo: denvilles_duo/Flickr The tunnel was dug under the direction of the Greek engineer, Eupalinos of Megara, who many consider to be the first hydraulic engineer in history. The purpose of the tunnel was to supply the ancient capital of Samos, today called Pythagoreion, with fresh water. The city of Samos had outgrown the capacity of the wells and cisterns within the city's limits, but the main source of fresh water on the island was on the other side of Mount Kastro from the city. It was decided that an aqueduct be built under the mountain to keep it concealed from enemies, who might destroy it and cutoff water supply to the city. The tunnel was dug from both ends and met beneath Mount Kastro’s highest point. In order to make sure the two ends met, Eupalinos arranged for the two straight shafts to be dug towards the meeting point at an angle. This way, Eupalinos had only to ensure the shafts were dug at the same level. As long as the two digging teams maintained level, the two shafts would eventually cross each other. Eupalinos was aware that failing to meet would be catastrophic.