In 524 BC, when Pythagorio (then called Samos) was the island’s capital and a bustling metropolis of 80,000, securing sources of drinking water became crucial. To solve the problem, ruler Polycrates put his dictatorial whims to good use, ordering labourers to dig into a mountainside according to the exacting plan of his ingenious engineer, Evpalinos. Many workers died during the dangerous dig, but the result was the 1034m-long Evpalinos Tunnel. In medieval times, locals used it to hide from pirates.
The Evpalinos Tunnel is actually two tunnels: a service tunnel and a lower water conduit visible from the walkway. You enter the tunnel on narrow stairs, and it's single file from there. Not much more than 100m of tunnel is accessible, but it's enough to be impressed by this golden-age engineering feat.
