Greece. Samos. Part view of the Tunnel of Eupalinos or Eupalinian aqueduct. Considered the 8th wonder of the ancient world and dating from around 550 BC during the time of the tyrant Polycrates rule of Samos, the 1350 metre long tunnel was built by the engineer Efpalinus improve the water supply to the city of Pythagorio by divert water from a spring through the mountain. The tunnel was simultaneously advanced from two opposing sides of the mountain and the workers met after five and half years of construction in the middle of the mountain. The tunnel was used for least a thousand years.