Baptistery of a three-aisled Early Christian basilica, built over the ruins of the temple of Athena.
Byzantine fortifications. These are on the east side of the hill and constructed with material taken from the ancient temple of Athena. Parts of the repairs made by the Knights are visible.
Ruins of the katholikon of a Byzantine monastery. This is a cruciform inscribed church of the C type, and dates from the end of the 10th to the beginning of the 11th c.
Medieval monastery restored during the Italian occupation. Around the interior courtyard are the rooms of a two-storey building with arched porticos leading to the monks' cells on the ground floor and the Abbot's quarters on the first floor.
Single cell chapel of Ayios Georgios Chostos, with 15th c. frescos in an eclectic style.
Excavations were carried out by the Italian Archaeological School (in 1914 and 1923-1926) during their occupation of the island. The earliest phases of the temple of Athena were excavated as well as the depository containing figurines, pottery and metal objects (9th-5th c. BC). The Doric fountain-house was also excavated and restored at this time.