Nestled in the mountains at Pythagorion on Samos lies the Eupalinos Tunnel – a hidden gem that takes you on a journey through time. The Eupalinos Tunnel is considered as the first underground project excavated with a geometry-based approach. This remarkable feat of ancient engineering showcases the brilliance of the minds that conceived it in the 6th century BC. In 1992 UNESCO declared the area of Eupalinos Aqueduct a World Cultural Heritage site.

Today, visitors to the Eupalinos Tunnel can traverse the same path that ancient Samians once relied upon for their water supply and refuge during times of war.

The Origins

In 550 BCE the construction of the Eupalinios Aqueduct and Tunnel was commissioned by the visionary Greek engineer, Eupalinos of Megara. The purpose was to create a steady supply of water to the ancient city of Samos and groundbreaking methods were used in its construction.

Carved through solid limestone, the tunnel spans over 1,036 meters, burrowing through the heart of Mount Karvounis (Kastro). The aqueduct ingeniously taps into an underground spring north of the summit, ensuring a reliable water supply for the city on the south even during times of siege.

The method

Eupalinos and his team used the “digging from both ends ” method. Two crews of stonemasons and slaves, working simultaneously with hammers and chisels from opposite sides of the mountain, met in the middle with incredible precision. The deviation was only 12 centimeters, so the engineers managed to maintain a nearly perfect straight line through the rocky labyrinth.

It is estimated that 8-10 years were required to complete the project.

The Aqueduct of Eupalinos

The Aqueduct of Eupalinos has a total length exceeding 2,5 km. The bored tunnel of Eupalinos (1036m long) consists of a corridor (1.80m x 1.80m) and a water ditch (0.60m wide) with a depth ranging from 4.0m in its northern section to 8.9m in its southern one, to ensure gravitational water flow.

The maximum overburden of the tunnel is 170m below the summit of the mountain and its elevation is 55m above sea level.

The aqueduct starts from the Ayiades spring, where water was collected in a rectangular reservoir covered by stone slabs. The reservoir supplied 400 m3 per day, which was transferred through an underground clay pipe (length: 890 m) to the northern entrance of the tunnel. It was then carried from the tunnel’s southern exit to reservoirs and fountains in the ancient city via a pointed underground built channel with manholes at intervals. The Eupalinos tunnel is the central section of the aqueduct, consists of the “” within with the water  was channeled through clay pipes, parts of which are still visible.

The tunnel was first discovered in 18543 by Victor Guerin, a French archaeologist who searched for the “great spring” of Herodotus. In 1882 the monk Kyrillos Moninas from the nearby Agia Triada monastery discovered the south and north entrances of the main tunnel