Eupalinos Tunnel Eupalinov Tunel Samos

The Eupalinos Tunnel, ancient engineering wonder

Eupalinos tunnel is located on Greek Samos island, in the eastern Aegean Sea.
It is an ancient engineering wonder, considering that it was built in the 6th century B.C. to serve as an aqueduct. The tunnel has been inscribed on the UNESCO Heritage Site list since 1992.

I was fascinated by the story of this tunnel. Therefore I decided to visit it during my vacation in Samos in August last summer. And it was a very interesting experience.
So, let’s walk together through the fantastic ancient Greek world!


The story about the Eupalinos tunnel

If Herodotus (481-425 B.C.), the ancient Greek historian, had not left a record of the tunnel, probably today we would not have known about it. Actually, Herodotus mentioned it in his Book 3 of the Histories, describing it as “one of the three greatest works by Samians among all Greek engineers”. Another two amazing works are the breakwater in the sea enclosing the port of Samos and the temple in neighbouring Heraion.

The Eupalinos tunnel was hidden for many centuries until one monk fell into a hole and found the source in the 19th century.
In 1853 the French Archaeologist Victor Guérin identified the spring that was feeding the aqueduct and discovered the first 400 meters. Then in 1882 the south and north entrances of the main tunnel were found and the first excavations and cleanings started. It was a very difficult job and the project was stopped. In 1884, the German archaeologist Ernst Fabricius investigated the tunnel again and published the first results of his measurements on a map.

Finally, the full excavations were done by Greek and foreign scholars from 1971-1973, under the direction of Ulf Jantzen and the German Archaeological Institute. The whole tunnel was cleaned from the silt in the full length and the detailed geodetics measurements were done by Hermann J. Kienast.

Since May 2017, the tunnel has been open to the public and has become a great tourist attraction on Samos Island.


The tunnel’s location 

The Eupalinos tunnel is located on Mount Kastro, above the ancient capital of Samos, today’s Pythagorion.

Mount Castro Samos

Mount Castro, Samos


Herodotus mentioned that it was built during the rule of the tyrant Polycrates c. 540-522 BC. It was named after the ancient Greek engineer Eupalinos, from the city of Megara, responsible for its construction.

The tunnel was dug to supply the ancient city with fresh water. The main source of the freshwater was there, on the mount. And it was a big problem to bring water to the city safely because of enemy attacks.
This tunnel is well known in the world because the two teams were digging it from opposite sides on the mount. And they met in the middle of the mount, with a small deviation from the straight line. Even today, it is a fantastic undertaking. And you can imagine how it was in the 6th century B.C.!

the Southern Entrance in the Eupalinos Tunnel Today

The southern entrance in the Eupalinos tunnel today


The Eupalinos tunnel construction

The tunnel is passing through limestone at the base of a Kastro Mount. It is about 55 meters above sea level and 180 meters below the top of the mountain.
The engineer Eupalinus has used geometry and mathematical skills to find the best way. He calculated a level above the mountain top and the sea level.

It is supposed the digging of the tunnel lasted between eight and ten years. Two teams were working simultaneously: one group on the north and one on the south of the mount. There were the “north line” and “south line”. However since two parallel lines could never meet because of the geological rock structures, Eupalinus changed the direction of both tunnels. The north tunnel was changed to the left and the south tunnel was changed to the right.

Therefore, the meeting point is the place with the right angle.

the Meeting Point in the Tunnel

The meeting point in the Eupalinos tunnel


The excavators worked with the hammers and chisels. The oil lamps were the only light in the darkness of the tunnel. The ventilation was terrible and work conditions were very difficult. Only two workers could work together because of the limited space in the tunnel.
By the way, the excavators were mostly captives and anyone who survived the digging would be released. But most of them didn’t survive the years spent digging the tunnel.


The aqueduct

The aqueduct started from the Ayades spring, where water was collected in a rectangular reservoir. The spring is covered by stone slabs and today there is the chapel of Ai-Yannis built on the top of it.

The total length of the aqueduct is about 2.5 km, and the central section of the aqueduct is 1,036 meters (3,399 ft) long. The interior average dimensions are 1.80m x 1.80m (5.9 by 5.9 ft). But in some parts, the height is about 1.50m and the width is only 42 cm!
Therefore, visiting the Eupalinos tunnel is not recommended for persons suffering from claustrophobia, panic attacks, lumbago, cardiac or respiratory problems, spinal diseases, or overweight people.

the Corridor in the Tunnel

The corridor in the tunnel


From the spring water was flowing through an underground clay pipe 890 meters long to the northern entrance of the tunnel. Then the water was carried from the tunnel’s southern exit to reservoirs and fountains in the ancient city via an underground built channel. It is supposed that the tunnel supplied about 400 m3 of water per day.

The next 150 meters of the canal is a system of successive lined vertical shafts. Their bottom ends are interconnected with underground galleries.

the Eupalinos Tunnel

The Eupalinos tunnel


Two levels of the aqueduct

The tunnel has two levels. Actually, the first 740 meters is a lower level including a canal 4 m deep in its northern section to 8.90 m in its southern one, to ensure gravitational water flow. Even today on its bottom you can see the remains of the clay pipes, used once for supplying the water.

The upper level was used for maintenance and the passage for the people. As I have mentioned before, the height of the aqueduct varies from 1.5m to 4.3m in the part of the meeting point and north tunnel portal. The sidewalls are supported by stone walls. And during our visit, we could hear words,  such as “Ouch… Aaah, my head …”,  including myself!

It is one of the reasons why you have to put a yellow helmet on your head 🙂

Inside the Tunnel

Inside the tunnel


And the final 500 meters of the canal were used to carry the water from the tunnel exit down to the central fountain in the city of Samos.

The Eupalinos aqueduct was used to supply the city with water for 1,100 years, up to the 7th century AD. But the water was full of calcium and the clay pipes were damaged, so the aqueduct was abandoned.
During Byzantine times, the tunnel was used as a refuge, both for people and animals, to protect themselves from enemies. So, you could enter the tunnel from one side of the mount and exit on the other side, and no one could see you! Amazing, isn’t it?


What do you need to know before visiting the Eupalinos tunnel:

Although the tunnel is a very popular tourist attraction, there are some things you should know before your visit.

  • As I have mentioned before, the tunnel’s interior dimensions vary and, therefore, the visit is not recommended for persons suffering from different health problems.
  • The inside temperature is about 16ºC, and the humidity is between 85 to 97%.
  • The entrance of the southern tunnel is very narrow with a few steep and tall steps. The corridor is 1.55h high and 0.55m wide.
  • The floor is rocky, wet and slippery, so put on comfortable, closed and non-slippery shoes, and forget the heels and flip-flops.
  • Every visitor must arrive 10 minutes earlier at the entrance and take a protective helmet. Water drips from the ceiling and you have to protect your head because of the rocky sidewalls.
    the Yellow Helmets Tunnel

    The yellow helmets, Eupalinos tunnel


  • The visit is not allowed for children under the age of 14, and children between 14 and 18 must be accompanied by adults.
  • Since the tunnel is very narrow in some parts, it is not allowed to carry big bags, especially during the third route. You could leave them in the box office at the entrance of the tunnel.
  • You can take photos, but flash is forbidden. Professional photos or videos are allowed only with special permission by the Hellenic Ministry of Culture and Sports.


Visiting the Tunnel of Eupalinos

There are three ways to visit the tunnel:

  1. The first route is 185 meters long. The duration of the visit is 20 minutes,  including the return. After the tall steps, you enter into the low and very narrow corridor 17 meters long. When you pass the corridor, you can walk normally. On this route, you can see all the construction details.

    Entrance in the Eupalinos Tunnel

    Entrance to the Eupalinos tunnel


  1. The second route includes 424 meters of the tunnel. There must be a maximum of 15 persons in a group. And the visit lasts about 40 minutes including the return. The floor is rocky, wet and slippery. Occasionally, water could drop from the ceiling. After 20 minutes we came to the meeting point where two groups met during the digging. In this part, you can see the remains of the clay pipes at the bottom of the aqueduct.
    Since we decided to take this route, we came back to the exit the same way.
the Remains of the Clay Pipes in the Bottom of the Eupalinos Aqueduct

The remains of the clay pipes at the bottom of the aqueduct


  1. The third route is 1.036 meters long, and the duration of the visit is about one hour. But there is only one way, which means you have to walk to the end of the tunnel and the cistern of Aigades in the north. In one part of this route, there is a very low and narrow corridor 197 meters long, with 0.42 to 0.6 m wide. Groups consist of a maximum of 10 persons.
    So if you decide to take this route, you have to organize a car or taxi waiting for you. Or you can walk about 45 minutes on a dirt road to the city of Pythagorion.
the Walls in the Tunnel

The walls in the tunnel


How to get to the Eupalinos tunnel

The south Entrance to the tunnel is about 2 km from Pythagorion town. You can come there by car or on foot. The taxi is approximately 5 Euros from the taxi station in Pythagorion. The North Entrance to the Tunnel is in the rural area of Agiades and it is not accessible by car.

The entrance ticket is 8 Euros, no matter which route you take.
But there is a special ticket package, which costs 13 Euros. With this ticket, you can visit four important sights, such as the Archaeological Museum in Vathy and Pythagorion, the Temple of Hera, and the tunnel of Eupalinos. Note that you have to visit all four sights in three days, so organize your time well.

Visiting hours are from 8:40, and the last term for the entrance is at 14:40. You can book your visit as well by telephone at +30 22730 62 813, or via email: It is especially recommended if you decide to take the third route or if you are coming with a group.


Visiting Eupalinos tunnel –  yes or no?

Well, visiting the Eupalinos tunnel is a real adventure.

If you are not claustrophobic and if you don’t have health problems, take a walk through the ancient Greek world.

The tunnel built in the 6th century B.C. to serve as an aqueduct is a fascinating example of engineering wonders,
for visitors, historians, and archaeologists.



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