7 Best Sights in The Northern Aegean Islands, Greece

Ancient Eresos crowned a hillside overlooking the sea, and sections of the pre-classical walls, medieval castle ruins, and the AD 5th-century church, Ayios 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 freely accessible. One of the largest theaters in ancient Greece is from the Hellenistic period and seated an estimated audience of 10,000. Pompey 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.

This rocky outcropping, where Homer is said to have taught his pupils, stands just above the port of Vrontados, 4 km (2½ miles) north of Chios Town. Archaeologists think an ancient altar to Cybele once stood on the rock; you can sit on it and muse about how the blind storyteller might have spoken here of the fall of Troy in The Iliad.

The early Samians worshipped the goddess Hera, wife of Zeus, believing she was born here beneath a bush near the stream Imbrassos. 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.

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. Hours may be shortened in winter.

At the eastern corner of Pythagorio lie the crumbling ruins of the Kastro, probably built on top of the ruins of the Acropolis. Revolutionary hero Lykourgou Logotheti built this 19th-century edifice; his statue is next door, in the courtyard of the church built to honor the 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 some nights 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.

Moria's Roman aqueduct dates back to the 2nd century, and the 17 arches that remain demonstrate how magnificent the structure was in its heyday. Constructed from gray Lesviot marble, the aqueduct stretched 26 km (16 miles) from Olympos mountain at Tsingos to Mytilini. It was in Lesvos that Julius Caesar first made his mark. Sent to Bythinia to drum up a fleet, he hung around so long at King Nicodemus's court that he was rumored to be having an affair with the king, but he finally distinguished himself by saving a soldier's life.

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 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 part of the length—also a wonderful way to enjoy natural coolness on swelteringly hot days. Though the tunnel has been closed for necessary engineering work, a partial opening is set for 2018. At some point, with ongoing work, it will be possible to traverse the tunnel in its entirety. On a hillside above the tunnel entrance are the scant remains of a Greek and Roman theater, and a wooden platform over the shell is occasionally used for performances.