Efpalinium Tunnel in Samos, Greece
This tunnel was one of the greatest constructions of the 6th century. It is a water tunnel that used to be the middle section of a huge aqueduct named after its architect, Efpalinus who was a famous engineer of the ancient world. The Efpalinium Tunnel supplied water to the ancient capital of the island and it was used until the roman period. This monument in Samos is very impressive to explore and frequently visited.