Aim and date
Good water is the primary requirement of any city. The quantity (17 cubic metres per hour) and quality of water rising year-round at the spring of Aghiades, 2.5km, as the crow flies, behind the mountain to the north of the city, made it the obvious source for Samos , which was fast growing into one of the largest cities in the Aegean in the 6th century bc. The water from the spring could have been channeled around the slopes of the hill and brought into the city from the west. But the fact that this was not done, and that the much more difficult task of bringing it directly through the mountain was chosen instead, indicates that an external aqueduct was possibly considered too vulnerable to attack by an enemy. It presupposes the existence of the enceinte of walls, to the inside of which the water needed to be safely brought: it also presupposes, as do the walls, an enemy or some imminent threat—most probably the increasing hostility of Persia in the period after 546 bc. This is the logical and accepted reasoning behind the tunnel. But the desire willfully to take on a challenge, or to show bravado in solving a daunting problem, is a fundamental element of the Early Greek character, and should not be excluded as a motivation for an enterprise of this complexity. The size of the giant Kouros and of the Temple of Hera, the boldness of the harbour mole, the journey of Colaios into the Atlantic Ocean—all enterprises of the Archaic era—suggest that there were other human impulses at work in the imagination of this extraordinary period, which go beyond a simple consideration of security for a water supply.
Archaeological evidence (potsherds, and the style of masonry in the areas of reinforcement), as well as the testimony of Herodotus, suggest that the tunnel could well have been commissioned by Polycrates, in the same period as the first circuit of walls and the harbour mole(s), i.e after 540 bc—even though some important authorities (notably the archaeologist, Hermann Kienast) put the start of the tunnel around ten years earlier, before the rule of Polycrates. The nature of the threat to Samos was apparently urgent enough to necessitate the bold decision to begin the tunnel from both ends simultaneously, so as to halve the time to completion. It was with that decision that the most interesting problems were raised.
Samos Island is part of the Northern Aegean Island Group, Greece.