The awesome people over at Ancient Origins recently posted a very iteresting article entitled: 'The Tunnel of Eupalinos: One of the Greatest Engineering Achievements of the Classical World'. It's about a subject I previously knew nothing about and perhaps the same holds true for you: an ancient tunnel that acted as an aquaduct to supply water for a prosperous and growing town.

The Tunnel of Eupalinos (or Eupalinos Tunnel) is located on the Greek island of Samos, and has been considered as one of the most important engineering achievements of the Classical world. It has been claimed that the construction of the Eupalinos Tunnel represents the first time in the history of mankind that a project on such a scale had been undertaken. Moreover, the planning and mathematical calculations that went into this project may be said to be on par with those employed by modern day engineers.

The Tunnel of Eupalinos was a project conceived during the 6th century BC. During this time, the ancient town of Samos, now known as Pythagorio / Pythagoreio / Pythagorion, was experiencing a period of prosperity. Along with this growing wealth, the town also saw an increase in the size of its population. Unfortunately, water sources in the town were not enough to satisfy the needs of its people. To maintain the prosperity of his town, the tyrant Polykrates had to find a solution to this problem, and employed the engineer Eupalinos of Megara to build an aqueduct.

Little is known about Eupalinos today. It is said that he was the son of a man by the name of Naustraphos, and came from a place known as Megara, which is situated between Corinth and Athens. The aqueduct was not the first project that Eupalinos had worked on under Polykrates. It has been recorded that, prior to this, Eupalinos was also commissioned to build the cyclopean wall that surrounded the town of Samos, as well as the mole in its harbor.
Eupalinos’ later project was an aqueduct, which was to connect the town of Samos to the north of Mount Kastro. It was from this mountain that the town would get its supply of water. From a spring on this mountain, water was conducted into a covered basin / reservoir, which is today under the old chapel of a deserted village by the name of Agiades. This aqueduct was completely subterranean, and it has been recorded that the water, from its source, travelled to the town of Samos over a total distance of over 2.5 km (1.5 mi). 1036 m (3398 ft.) of this distance involved a bored tunnel, which is perhaps the highlight of this monumental project.

Eupalinos could have used a much easier method to construct his aqueduct. This is known as ‘cut and cover’, and would allow the water to flow in a channel along the contours of Mount Kastro. For reasons that are unknown today, Eupalinos decided against this course of action, and instead decided to build a tunnel through the mountain.

This feat was accomplished by having the tunnel dug simultaneously from both ends. Using only picks, hammers and chisels, Eupalinos’ workers, many of whom are said to have been prisoners from Lesbos, dug their way through solid limestone. Clay / terracotta pipes were also put into place to facilitate the flow of the water. It has been estimated the whole system took about a decade to build. It has been speculated, that, when completed, Eupalinos’ creation supplied the town of Samos with 400 cubic meters of water per day.
The Tunnel of Eupalinos is said to have served its original purpose until the 7th century AD, when it fell into disuse during the Byzantine period. Following this abandonment, the tunnel was turned into a refuge by the local people, who hid in there when they were attacked by pirates. The tunnel’s defensive role may be seen in the fortressing walls that were built inside this ancient structure just after its southern entrance portal.

Eventually, however, the location of Eupalinos’ Tunnel was lost. Nevertheless, this structure had been mentioned in Herodotus’ Histories, which prompted many to look for it. It was only in 1853 that a French archaeologist by the name of Victor Guerin discovered the first 400 m (1312 ft.) of the aqueduct from the spring at Agiades. Over the next century, more discoveries were made, and eventually, in 1992, the Tunnel of Eupalinos became a UNESCO World Heritage Site as part of the ‘Pythagoreion and Heraion of Samos’.