Tunnel of Efpalinus (Pythagorion): One of the most significant works carried out during the Polycrates era. Even today one is filled only with admiration for the skill of the man from Megara. The tunnel was designed to carry water to the capital of the island. From historical records it is known that the piercing of the mountain started from both sides of the mountain, with the aim of meeting halfway. By assiduous digging, both teams of workers managed to meet inside the mountain, with the small difference in elevation of a couple of feet from one side to the other. The task took many years, and the tunnel has a total length of 1.350 metres. The other opening, on the other side of the mountain, is 1.70 metre high. There is a portal with an inscription at the entrance of the tunnel. The tunnel was constructed with the aid of primitive tools, without the help of measuring instruments, and the visitor is gripped with wonder when he thinks of this remarkable accomplishment.

The Castle of Lycourgos Logothetis (Pythagorion): Built during the first years of the last century on the foundations of an older Venetian castle,  is located next to the Church of the Transfiguration. It served as a jumping-off point for attacks on the Turks and as a refuge in time of danger during the difficult years of the War of Independence (1824).

Monastery of Spiliani (Pythagorion): About one kilometre from Pythagorion on the slope of Mountain Kastri is located the Monastery of PanaghiaSpiliani. Inside a deep cave is the small chapel of the Madonna. Outside the cave, there are coves that used to be the cells where the monks lived, as well as a newer small church.

Hera Temple (Ireon): The road which runs to Hereon passes through the fertile plain, running close to the shore. The famous temple of Hera was built in this area as the ancients believed that this was where the goddness was born. Menodotus says that the temple was constructed by the Leleges and the Nymphs, while Pausanias claims that the Argonauts were responsible for finding it. The first structure was destroyed and  a second Temple was built during the 8th or 7th century, only to be destroyed in turn by the forces of  King Cyrus of Persia. The third temple ( of which one incomplete column is seen to be standing today) was built under the rule of Polycrates by the Samiot architect Rhoikos. When the Persians once more destroyed it, Polycrates assigned the task of constructing the fourth temple to Theodoros, son of Rhoikos. Herodotus says that this temple was the largest and most luxurious that he ever saw. It was  built in mixed Doric and Ionic Order, and was dipteral – with a length of 108.73 m, a width of 54.68 m and a height of 25 m.

The Ancient theatre (Pythagorion): On the slope of Mountain Kastri, near the Monastery of Spiliani and at a somewhat lower elevation are found the ruins of the ancient Theatre.

Other Archaeological sites:

  • Roman Baths
  • Many ruins of temples in other parts of the island