5 Best Sights in The Northern Aegean Islands, Greece

Considered by Herodotus as the world's Eighth Wonder, this famed underground aqueduct was completed in 524 BC with archaic tools and without measuring instruments. The ruler Polycrates, not a man who liked to leave himself vulnerable, ordered the construction of the tunnel to ensure that Samos's water supply could never be cut off during an attack. Efpalinos of Megara, a hydraulics engineer, set perhaps 1,000 slaves into two teams, one digging on each side of Mt. Kastri. Fifteen years later, they met in the middle with just a tiny difference in the elevation between the two halves. The tunnel is about 1,018 meters (3,340 feet) long, and it remained in use as an aqueduct for almost 1,000 years. More than a mile of (long-gone) ceramic water pipe once filled the space, which was later used as a hiding place during pirate raids. Today the tunnel is exclusively a tourist attraction, and though some spaces are tight and slippery, you can walk the whole length—a wonderful way to enjoy natural coolness on swelteringly hot days—or part sections. On a hillside above the tunnel entrance are the scant remains of a Greek and Roman theater, and ancient city walls.

Ancient Eresos "was founded on a hill and lied by the sea" according to the Greek geographer and historian Strabo, and sections of the preclassical walls, medieval castle ruins, and the 5th-century-AD church, Agios Andreas, remain from the storied and long-inhabited site. The church has a mosaic floor and a tiny adjacent museum housing local finds from tombs in the ancient cemetery.

This vestige of ancient Mytilini is within a pine grove and easily accessed. One of the largest theaters in ancient Greece, it is from the Hellenistic period and seated an estimated audience of 10,000. Plutarch, in Pompeius, tells us that the Roman general admired it so much that he copied it for his theater in Rome. Though the marbles are gone, the shape, carved into the mountain, remains beautifully intact.

The early Samians worshipped the goddess Hera, wife of Zeus, believing she was born here beneath a bush near the Imbrassos stream. Several temples were built on the site in her honor, the earliest dating back to the 8th century BC. Polycrates rebuilt the To Hraio, or Temple of Hera, around 540 BC, making it four times larger than the Parthenon and the largest Greek temple ever conceived, with two rows of columns (155 in all). The temple was damaged by fire in 525 BC and never completed, owing to Polycrates's untimely death. In the intervening years, masons recycled the stones to create other buildings, including a basilica (foundations remain at the site) to the Virgin Mary. Today you can only imagine the To Hraio's massive glory; of its forest of columns only one remains standing, slightly askew and only half its original height, amid acres of marble remnants in marshy ground thick with poppies in spring.

At the ancient celebrations to honor Hera, the faithful approached from the sea along the Sacred Road, which is still visible at the site's northeast corner. Nearby are replicas of a 6th-century-BC sculpture depicting an aristocratic family; its chiseled signature reads "Genelaos made me." The kouros from Heraion was found here and is now in the Archaeological Museum in Samos Town.

At the eastern corner of Pythagorio lie the crumbling ruins of the Kastro, probably built on top of the ruins of an older acropolis. Revolutionary hero Lykourgou Logotheti created this 19th-century edifice; his statue is next door, in the courtyard of the church built to honor a victory. He held back the Turks on Transfiguration Day, and a sign on the church announces in Greek: "Christ saved Samos 6 August 1824." On saint days the villagers light votive candles in the church cemetery, a moving sight with the ghostly silhouette of the fortress and the moonlit sea in the background. Nearby are some fragments of the wall that the ruler Polycrates built in the 6th century BC.