Eupalinos' tunnel

In Samos the first Trireme ship, the Samaina, was build. It was the birthplace of Pythagoras and Aristarchus. The capital town of Samos had a inadequate water supply making life difficult in the hot, dry summers. The city could not resist for a long time enemy attacks. The mountains behind the town offered a source of water from the storms that broke over the mountain tops and the streams that ran through them.

For these reason the most famous hydraulic work of ancient Greece was build: The aqueduct of ancient Samos, which was admired both in antiquity (e.g. Herodotus) and in modern times. Herodotus considered the temple of Hera in Samos, the Samian harbor and the Eupalinos tunnel one of the greatest things he had seen throughout his travels in the Ancient World. The harbor of Samos was build 540-523 BC during Polycrates. A wave breaker, 370 meters in length and 35 meters of depth inside the sea, was built for its protection. It is still there although due to the sinking of the ground now it is immersed at the bottom of the bay of Tigani.

A Tunnel, through Mount Kastro on Samos, was build to bring water from north of the mountain inside the fortifications of the city of Samos (modern Pythagoreon) to the south.

The most amazing part of the aqueduct is the 1036 m long, roughly 8 feet square, dug from two openings, «Ευπαλίνειον όρυγµα», or “Eupaninean digging”, after Eupalinos, an engineer from Megara. Its construction started in 530 BC, during the tyranny of Polycrates and lasted for ten years. The two working groups met in the center of the channel and they had only 60 cm error! The workers had problems because of unstable soil they found and had to make a deviation, but they managed to find again the right way to the opposite working team. The deviation was 200 metres away from a straight line connecting the ends of the tunnel in the heart of the mountain! Around 7000 cubic meter rock were removed from the mountain. Owing to the text of Herodotus, Guerin (1856) uncovered the entrance of the aqueduct. Only ninety years later, between 1971 and 1973, the German Archaeological Institute of Athens uncovered the entire tunnel (Kienast, 1977; Tsimpourakis, 1997).

Image from Demetris Koutsoyiannis Lectures

Image from Demetris Koutsoyiannis Lectures


T. E. Rihll and J. V. Tucker, Greek engineering: the case of Eupalinos' tunnel, in A Powell (ed) The Greek World, Routledge 1995.

Greek ministry of culture page on the tunnel with photo here.

Approximately 500 years later Heron described methods how to produce tunnels with his Dioptra. So the ancient Greeks must have a sufficient advanced geometric knowledge and the corresponding measuring devices to produce the Eupalinos channel.

Example by Heron how to use the Dioptra to construct a tunnel through two opposite points in a mountain. Take a point close to the first entrance B and another point E. Then use the Dioptra to obtain the perpendicular line EF and through a set of other perpendicular segments get line segment KL the point M for which DM is perpendicular to KL, where D is the other opposite entrance point. Using DN and NB estimate the angle alpha necessary to connect points B and D.


Demetris Koutsoyiannis, Water resources technologies in the ancient Greece, School of Civil Engineering National Technical University of Athens

Buffet, B., and R. Evrard. (1950). L’Eau Potable a Travers Les Ages. Editions Soledi, Rue de la Province, 37, Liege, Belgium.

Dooge, J. C. I., (1988). Hydrology, past and present. Journal of Hydraulic Research, 26(1), 5-26.

Guerin, V. (1865). Description de l’Ile Patmos et de l’Ile Samos, Paris.

Kienast, H. J., Der Tunnel des Eupalinos auf Samos, Architectura, Zeitschrift für Geschichte der Architektur, 97-116, 1977.

Korres M. (2000), Water supply of Athens in antiquity (in Greek). Workshop: "Water and Environment", EYDAP, Athens.

Koutsoyiannis, D., and T. Xanthopoulos (1999). Engineering Hydrology (in Greek). 3rd edition, 418 pages, National Technical University of Athens, Athens.

Lazos, C. D. (1993). Mechanics and Technology in Ancient Greece (in Greek). Aeolos, Athens.

MacDowell, D. M. (1978). The Law in the Classical Athens. Thames and Hudson, London.

Papademos, D.L. (1975). The Hydraulic Works in Ancient Greece, Vol. B (in Greek). Ed. TEE, Athens.

Pappas, A. (1999). The Water Supply of Ancient Athens (in Greek). Eleuphtheri Skepsis, Athens.

Tsimpourakis, D. (1997). 530 BC, The Digging of Eupalinos in Ancient Samos (in Greek). Editions Arithmos, Athens.

U.S. Committee on Opportunities in the Hydrological Sciences (1991) Opportunities in the Hydrologic Sciences. National Academy Press, Washington, DC.


The Tunnel of Eupalinos

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