• Description

The “Tunnel of Eupalinos” (Greek: Efpalinio orygma, Ευπαλίνειο όρυγμα) or “Eupalinian aqueduct” or “Amphistomon orygma“(= a tunnel having two openings) as Herodotus described it, is an insurmountable task in the history of engineering technology and an important testament of the great engineering skills and knowledge level that the ancient Greek engineers possessed.

The project took place in the second half of the 6th c BC by the engineer Eupalinos of Megara (in west Attica), during the period of Polycrates tyranny. The aim of the project was to supply water from the source of “Agiades”, (hidden at the mountain away from enemies), to the ancient city of Samos, through mount “Kastron”. The result was a remarkable water pipeline, total length 2,385 meters, of which 1,035 passes through the tunnel.

The water pipeline starts at the water source, for the first 600 m, in depth of 2.5 meters with constant 0.6% grade, and then it continues for the next 260 m with a constant 0.75% slope. This section was constructed by connecting the bottoms of five wells. Then the conductor pipes enter a 1.035 m long tunnel, perfectly horizontal (the northern mouth is located at 55.48 m height and the southern at 55.17 m height). The tunnel has dimensions 1.80 x 1.80 m and at the floor lies a ditch (inclined), 0.6 m wide and up to 10 m depth, in which they placed clay cylindrical tubes (cut in half) 0.40 m wide, from where the water passed. At the southern mouth of the tunnel, and for the remaining 490m, pipes directed the water into the city reservoir.

To save time, the construction of the tunnel took place with the simultaneous work of two working groups, one from the north and one from the south and they managed to meet each other in the middle, at a depth of 180 meters from the top of the mountain.

  • History

The aqueduct was the work of Eupalinos, son of Naustrophos, an engineer from Megara. Its construction started in 550 B.C., during the tyranny of Polycrates and lasted for ten years. Many slaves (mainly from Lesvos Island) were used by the Samians for the completion of the work.

For the completion of this project many problems had to be solved. Amongst them intractable geometrical problems (determination of altitudes, slopes, setting out the horizontal plane and more), since the knowledge of geometry was still limited and the surveying instruments unknown. Therefore it’s still riddling, as to how they managed to find solutions to all these difficulties.

The tunnel is the second known tunnel in history which was excavated from both ends, and the first with a geometry-based approach in doing so (the oldest known tunnel, at which two teams advanced simultaneously was the –much smaller- Siloam tunnel in Jerusalem, completed around 700 c BC.)

There were also other solutions, simplest, cheapest and equally safe for the construction of the aqueduct, still it is said that Polycrates chose this innovative and unique approach, desiring to impress, show his wealth, power and greatness and at the end he succeeded.

The aqueduct was used for about a thousand years, although during the Roman era, a new aboveground aqueduct using arches was built, from “Megali panagia” monastery to the city, with a total length of 15.5 km.

As proved by the archaeological findings, the tunnel was known until the 7th c AD, but from there on there was no reference to it anymore, and it was forgotten. Several archaeologists searched for the tunnel later on, according to the references made by Herodotus, but without positive results.

Finally, the northern mouth of the tunnel was discovered accidentally in 1872, by Cyril Moninas, abbot of Agia Triada monastery. The southern mouth was discovered in 1874 by Theofanis Arelis, abbot of Timiou Stavrou (Holy Cross) monastery. The successor of Cyril, monk Synesios Giannou, managed to cross the whole tunnel and wrote in 1899 “Treatise of Efpalio tunnel”.

  • Video anmimation

 “Maths Bring Water to SamosVirtual Tour (interactive panoramas) for construction of Eupalinian aqueduct,

  • World Heritage Monument

Tunnel of Eupalinos classified World Heritage Monument by UNESCO since 1992. Ιntegration within the wider region of Pythagoreion.
Name & Location Pythagoreion of Samos
State Party Greece
Coordinates N37 41 27.00 E26 56 36.00
Area Property: 285.9 Ha Buffer zone: 402.25 Ha
Map click for pdf file
UNESCO website

  • International Tunnelling Landmark

At the “World Tunnel Congress 2015” Conference in Dubrovnik, Croatia on 25 May 2015, the Tunnel of Eupalinos was proclaimed International Tunnelling Landmark by the International Tunnelling & Underground Space Association (ITA – AITES), and handed over to the Greek Commission for Tunnels & Underground Projects .E.E.S.Y.E.) Special plaque and certificate honorary. It is noted here that this was the first time – internationally – that this title was institutionalized.

  • International Historic civil engineering Landmark

At 2017 the American Society of Civil Engineers (ASCE) recognized the Tunnel of Eupalinos as an “International Historic civil engineering Landmark” and at a ceremony held at the Tunnel at 29/10/2017 a special plaque was posted.


Visiting Tunnel of Eupalinos

  • Visiting routes
    there are 3 ways to visit the Tunnel.

Itinerary 1. Length 185 m., maximum number of visitors 20, duration 00:20΄ including return. In this part one can see all the construction details.
Difficulties : a narrow stairway with steep, tall steps and a low and very narrow corridor 17 m. long, 1,55 m. high, 0,55 m. wide. Fairly easy after the corridor.

Visiting hours: 08:40΄, 09:00΄, 09:40΄, 10:00΄, 10:40, 11:00΄, 11:40΄, 12:00΄, 12:40΄, 13:00΄, 13:40΄, 14:00΄, 14:40΄

Itinerary 2. Length 424 m., maximum number of visitors 15, duration 00:40΄ including return. Visitors should book in advance date and time by phone: +0030 22730 62813. One can see a cistern of byzantine period and the meeting point of the two working groups.
Difficulties : All the above mentioned and rocky, uneven floor, wet and slippery in some areas, and water dripping from the ceiling in some parts.

Visiting hours: 08:20΄, 09:20΄, 10:20΄, 11:20΄, 12:20΄, 13:20΄, 14:20΄

Itinerary 3. Length 1036 m., maximum number of visitors 10, duration one hour, one way. Visitors should book in advance date and time by phone: +0030 22730 62813. One can see the whole tunnel and visit the spring and the cistern in Agiades.
Difficulties : All the above and fatigue. Especially difficult is the passage through the north low, narrow corridor 197 meters long, 0,42 – 0,60 m. wide. There are neither facilities, nor public transport from the north exit to the city. One has either to have prearranged for a car to wait for him, or to walk for about 00:45΄ minutes through a dirt path in order to reach the city of Pythagoreion.

Visiting hours: At 08:30΄ from the South Entrance, 09:20΄ from the North Entrance, 10:20΄ from the South Entrance, 11:20΄ from the North Entrance, 12:20΄ from the South Entrance, 13:20΄ from the North Entrance.

Author P. J. Chatzidakis

  • You should know, visiting the Tunnel of Eupalinos

Undoubtedly the Eupalinos Tunnel, the central part of the ancient aqueduct, is an admirable achievement of engineering worth seeing, however visitors should bear in mind that:

The tunnel is 1036 m. long. The average dimensions are 1,80 m high and 1,80 m wide, but in some parts the height is as low as 1,50 m. and the width is as narrow as 0,42 m.

The rocky, uneven floor is wet and slippery in some areas and from the ceiling is dripping water in some parts. The temperature is 16,5 – 16,7°C (degrees Celsius) and the humidity is 85 – 97%.

Therefore overweight people, visitors suffering from claustrophobia, panic attacks, lumbago, cardiac or respiratory problems, spinal diseases, musculoskeletal disorders causing moving difficulties are strongly advised not to enter.

Visitors who, after the above, decide to visit the Tunnel, they will do so on their own responsibility. In case of an accident the Greek State will bear no responsibility.

Visitors must not carry big bags; they should leave them at the entrance of the tunnel. Visitors doing the Itinerary 3 cannot carry any bags at all.

All visitors must wear protective helmets (provided) and closed flat, non slippery shoes. They should be in the entrance 00:10΄ earlier to wear their protective helmet.

For the present children less than 14 years old are not allowed inside the Tunnel. Young people between 14-18 years of age should be accompanied by a responsible adult.

Guides must talk about the history of the Aqueduct outside the Tunnel. Inside the Tunnel they can only point out areas of interest.

Photography with a hand-held, non professional camera is allowed free of charge but the use of flash is forbidden. Professional photography or video are not allowed without a special permission issued by the Hellenic Ministry of Culture and Sports.

Τhe South Entrance to the Tunnel is about 2 klm from Pythagoreion and is accessible by car, or on foot. The North Entrance to the Tunnel is in the rural area of Agiades, it is not accessible by car and visitors will have to walk on a dirt road for about 00:20′. Make sure you get directions in advance. For information tel. +0030 22730 62 813

Author P. J. Chatzidakis

  • Admission

  • Tickets
    Full: 8 € (for all three itinerairies)
    Reduced: 4 € (for all three itinerairies)
  • Special ticket package
    Full: €13,
    Reduced: €7
    3 days ticket for, Tunnel of Eupalinos, Archaeological Site of Heraion, Archaeological Museum of Samos and Archaeological Museum of Pythagoreion
  • Reduced admission
    Escorting parents on educational visits of primary schools,
    Greek citizens and citizens of E.U. who are over 65 years old,
    Students of University – Higher Education Institutes
  • Free admission
    Young people, up to the age of 18
    Students of University – Higher Education Institutes, of EU member states,
    Parents of multi-child or with three children families and their children up to the age 23 or 24,
    Persons with disabilities (67 % or over) and one escort,
    Single parent families with minors
    Escorting teachers during educational visits of schools,
    The employees of the Hellenic Ministry of Culture
    The police officers of the Department of Antiquity Smuggling
    Members of Societies and Associations of Friends of Museums and Archaeological Sites,
    Members of the Chamber of Fine Arts of Greece and equivalent Chambers of member-states of the EU,
    Members of the ICOM-ICOMOS,
    Journalists ,
    Official guests of the Greek State,
    Holders of a valid unemployment card,
    Holders of a solidarity card
    Holders of a free pass,
  • Free admission days for all
    6 March (in memory of Melina Mercouri)
    18 April (International Monuments Day)
    18 May (International Museums Day)
    The last weekend of September annually (European Heritage Days)
    28 October (National day)
    Every first Sunday from November 1st to March 31st



Opening Hours




08:30 - 14:40


08:30 - 14:40


08:30 - 14:40


08:30 - 14:40


08:30 - 14:40


08:30 - 14:40

For some Itinerary at the Tunnel, visitors should book in advance date and time by phone: +0030 22730 62813. Please see the text above, with routes and hours of visit.


Our Address:

Pythagoreion Τ.Κ. 83103 Samos


37.694647276005, 26.929896235466

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Chris 03/03/2018 10:48

Mind blowing.

Sophie 12/08/2017 13:55

Fabulous place which is a testimony of the glorious antic Greek engineering and that has to be visited.
BUT it is a pity (and even a shame) that :
– Only very succinct explanation is provided by the guide at the start of the visit prior to entering into the tunnel and no more during the visit (guide is not allowed to provide explanations during the visit !!!). They rely on the availability of a leaflet at the entrance desk which is clearly not enough and which is not available in other languages than Greek and English.
=> There is a very very good and interesting reconstitution film about the tunnel building at the time of Eupalinos on the www.samosin.gr website that should be projected to the visitors prior to starting the visit!
– Children =6 years old as long as they are accompanied by an adult for the itineraries 1 and 2.
– the same price for all the itineraries is for sure too expansive for the itinerary 1 with such conditions!!!
In conclusion, a fabulous place to visit but that cannot become famous and tourist-attractive as long as there is no improvement from the Ministery to achieve educational goals.