The Pythagoreion is the archaeological site of the ancient town of Samos in Samos, Greece. It is located in the area of the modern town of Pythagoreio, from which it has got its modern name. The archaeological site contains ancient Greek and Roman monuments and a famous ancient tunnel, the Tunnel of Eupalinos or Eupalinian aqueduct. Along with the Heraion of Samos, the Pythagoreion was registered as a UNESCO World Heritage Site in 1992 because of its testimony to the cultural, military, and economic importance of Samos during Archaic and early Classical Greece.