Tunnel of Eupalinos: A unique feat in the history of engineering

The answer is about eight to ten years, but that did not stop Eupalinos, the ancient Greek engineer responsible for the construction of the Eupalinos Tunnel, an aqueduct at Pythagoreio, in Samos.

Herodotus’ reference constitutes the sole source on this unique engineering achievement, which would have been otherwise lost in the mists of time. Thanks to his description it was rediscovered in 1853 and has been declared a UNESCO World Heritage Site, as it is one of the most important feats in the history of engineering.

Construction of the aqueduct began around 550 BC, with two crews digging on both sides of the mountain at the same time and meeting in the middle, thanks to Eupalinos’ precise mathematical calculations. The tunnel is 1,036m long and measures 1.8×1.8m on average; it channelled water to the cisterns and fountains of the ancient town by means of clay pipes. The men were working by oil lamp light, which made their already arduous work even harder, polluting the atmosphere.

The reason why the aqueduct was built inside the mountain was to remain impregnable from any invaders; it even provided shelter from Persians and Arab attacks in later times, when it had been abandoned due to salt and other materials building up.

Descending into Eupalinos’ tunnel is like touring through the mind of the great engineer, who braved every risk of failure in a seemingly impossible project at the time, thanks to his profound faith in mathematics.