Tunnel of Eupalinos in Samos, Greece; a technical miracle of the 6th century B.C.

In this article we present information on the Tunnel of Eupalinos (or Eupalenion aqueduct) in Samos, Greece, a monument proclaimed as an International Historic Landmark, by the American Society of Civil Engineers (ASCE) and also adopted by UNESCO as a World Heritage Site.

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The Eupalenion Aqueduct in Pythagorion, Samos, is a world-famous monument of human construction, an unforgettable technical work that operated successfully for about 1100 years.


The Eupalenion is a 1036m long tunnel near Pythagorion, Samos, which was built in the 6th century B.C. to serve as an aqueduct. Its particular feature was that it was opened at the same time on both sides of the mountain: this trench was open at both ends as Herodotus notes. It was thanks to the ancient “father of history” that it became known. The two tunnels met roughly in the middle with remarkable precision, which was a major achievement for the technology of the time.


The reason there exist two parallel tunnels is that at the time of designing and implementing the project the source was at a certain height (higher than the level of the tunnel), but after the main stoa was constructed, the source began to flow lower, so it could no longer flow through this course. For this reason it was necessary to open an auxiliary, smaller tunnel at a lower level. The smaller tunnel was drilled through the main gallery, with the help of vertical troughs.

Herodotus, the only source we have for the Eupalinos tunnel, describes both the main and the auxiliary tunnels.

There is still ongoing discussion on “how it was designed, how the levels of the two entrances were determined, and how the direction of alignment of the tunnel was determined”. As for the dating of the monument, the specialists believe it to have been built before the period of Polycrates, around the middle of the 6th century B.C.

Tunnel of Eupalinos seems to have been a quite innovative project for its time. Its design and construction required a high level of intelligence and knowledge, method, craftsmanship, collective work and education.

For us today, it constitutes an excellent example of the technical abilities of the Ancient Greeks.

(Source: http://www.newgreektv.com/english-news/item/23705-the-wondrous-eupalenion-aqueduct-of-samos-was-declared-an-international-landmark-of-engineering)

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Abstract In this paper the effort of surveying the Eupalinian Aqueduct is presented. This detailed survey has been carried out during spring 2009 in the framework of a study in order to restore it and make it available to the general public. Several methods have been used for the survey such as classic topographic using precise total station, GPS measurements and laser scanning. The final results are plans in 2D & 3D and virtual models. The Eupalinian Aqueduct is a remarkable water pipeline created 2500 years ago. Its main section is the tunnel of Eupalinos described by the ancient historian Herodotus. Due to his description the tunnel was looked for and discovered in the last century. The German archaeological Institute, free-vacated and investigated the entire plant in early ’70s. The antique water pipeline has its beginning beyond the city wall mountain at a spring in the village Agiades. From there it leads the ridge on a length crossed by 900 m underground up to the north slope of the mountain, in a tunnel of 1036 m length and runs further 500 m at the south slope to the city side into a well house. The entire water pipeline is a technical masterpiece of first rank adopted by UNESCO as a World Heritage Site. The tremendous achievement, which the construction of this plant means, can be appreciated most simply by numbers: For the inlet approximately 1500 m³ grown rock, for the tunnel with the channel approximately 5000 m3 had to be dug and for the city line again 500 m³. All these works were accomplished with hammer and chisel, other aids were not available. We can only roughly estimate how long it took for this construction. However for the tunneling through the mountain, at which locally only two laborers could work at a time, eight years is a fair guess, so for the entire scrapings probably it took almost ten years. The tunnel lies at 55 m above sea level approximately and thus 180 m under the summit. It has an average cross section of 1,80 m to 1,80 m and runs, with small deviations, horizontally. The channel, in which the pipeline was sited, has a 4 m depth at the north entrance of the tunnel and more than 8 m at the south exit.

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The aim of the engineer that undertook the work, Eupalinos, was to create a tunnel through the mountain Ampelos so that he could bring the water in the city of Samos, which today is named Pythagorion. The spring of Agiades was found behind the mountain Ampelos in the north-west of the city. It had allowance of 400m3 per day and it was shaped from the antiquity in order that the water gushes out through the natural rock. It had been covered in order not to locate and also the altitude of her level was in 52 meters. The engineer of work should have accomplished to supply the city water from the source of Agiades, the pipeline was underground, through the mountain, so that it was not localized from by any chance enemies and the orifice that flows in the city should be found inside the walls and in altitude that would ensure the effortless flow in all the city.

The possible ways of the pipeline were perimetrically the mountain, with surface ditch, or underground under the mountain with tunnel. Eupalinos chose the second solution. What led him to this solution, if he followed the first, then, because of the total length of the pipeline and the hydraulic bent, the water would reach the city in lower altitude and would have problems in the flow to the houses. The reasons that led him to his manufacture were the water shortage, the weakness of satisfaction of needs in water from wells and the guarantee of water supplies in the siege event.

Eupalinos constructed 870 meters of covered pipeline from the spring until the mountain, in undergrounds of builder ditch, afterwards 1036 meters in the tunnel, which was opened in the mountain and finally 520 meters from the mountain in the reservoir of the city, again in ditch. The tunnel was manufactured horizontally, (for the fear of underground waters) and straight, (in altitude of +55.8 meters from the sea level). It has been constructed amphistomous, (excavated simultaneously from both edges, for saving of time) and afterwards constructed a ditch along the floor of the horizontal tunnel, through which the water was channeled in the reservoir of the city with earthen
half pipes. The horizontal tunnel with a length of 1036 m. begins from northern side of mount Ampelos, (nowadays Castle), and leads to the southerner. It was founded 180 m. under the top of the mountain. The tunnel has orthogonal crosssection with dimensions 1.80 x 1.80 m. In the tunnel and indepth 3.5-8.5 meters was created a channel with the pipeline with bent 0.6% that transported the water in the city. This manufacture proves the high level of knowledge and the way of confrontation of problems that had the engineers of the 6th century B.C. For this construction they were essential knowledge of mathematics, geometry, topography and geodesy. Even today constitutes feat a work as and this, much more in his season with the means that had in his disposal, (Eupalinos).

(Source: “Surveying the Eupalinian aqueduct in Samos island”, by Konstantinos Tokmakidis)

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Suggested Relative Book: The Aqueduct of Eupalinos on Samos, by Hermann J. Kienast, Archaeological Receipts Fund, Directorate of Publications, 2005

The following video gives the reader a good sample view of the monument:

Research-Selection for NovoScriptorium: Philaretus Homerides

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