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The Tunnel of Eupalinos: One of the Greatest Engineering Achievements of the Classical World

The Tunnel of Eupalinos: One of the Greatest Engineering Achievements of the Classical World

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The Tunnel of Eupalinos (or Eupalinos Tunnel) is an ancient tunnel that functioned as an aqueduct. This 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.

History of the Tunnel

The Tunnel of Eupalinos was a project conceived during the 6 th 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.

Tunnel of Eupalinos (Eupalinian tunnel)

Tunnel of Eupalinos (Eupalinian tunnel) (CC BY-SA 4.0)

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.

Aqueduct Project

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.

Entrance of tunnel.

Entrance of tunnel. (CC BY-SA 2.0)

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 7 th 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.

The sign at the end of the part of the Eupalinian aqueduct that is open to the public.

The sign at the end of the part of the Eupalinian aqueduct that is open to the public. (Public Domain)

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’.

Top image: An internal view of the Tunnel of Eupalinos. Photo source: (CC BY-SA 4.0)

By Wu Mingren


Greek Tunnelling Society, 2014. Eupalinos Tunnel. [Online]
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Hughes, D., 2000. The Tunnel of Eupalinos. [Online]
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Samos Guide, 2016. Tunnel of Eupalinos. [Online]
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Schram, W. D., 2006. Samos Eupalinos. [Online]
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UNESCO, 2016. Pythagoreion and Heraion of Samos. [Online]
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The reason he went for a subterranean tunnel was very likely to protect the water supply from being cut in case of a siege.

During Polycrates' rule, the Spartans besieged the city of Samos and failed - they would have succeeded easily if they could have cut off the city's water supply.

dhwty's picture


Wu Mingren (‘Dhwty’) has a Bachelor of Arts in Ancient History and Archaeology. Although his primary interest is in the ancient civilizations of the Near East, he is also interested in other geographical regions, as well as other time periods.... Read More

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