The Tunnel of Eupalinos or Eupalinian aqueduct is a tunnel of 1,036 m length in Samos, Greece, built in the sixth century BC to serve as an aqueduct. The tunnel is the second known tunnel in history which was excavated from both ends, and the first with a methodical approach in doing so. The Eupalinos tunnel was also the longest tunnel of its time. Today it is a popular tourist attraction.
