Eupalinus tunnel, the most important part of ancient aqueduct and unique technical acheivement of antiquity from the 6th century BC is considered by many to be the 8th wonder of the ancient world. The aqueduct in total lenght over 2300 m started from the Agiades spring. Large terracotta pipes situated 4 - 9 meters lower under the tunnel passage (1036 meters long) used for maintenance, carried water through the mount Kastri (overlooking todays town of Pythagorio) and supplied the ancient capital of Samos. The aqueduct was in use at least 1000 years. The Eupalinus tunnel, mentionned by Herodotus, discovered in year 1881 by the priest of the Agia Triada monastery and excavated 1971 – 3 is accessible for the visitors. UNESCO WORLD HERITAGE SITE since 1992.