If you take the small dirt road detour from the asphalt road to Chora, right after the beach of Episkopi, you will end up at a currently abandoned archaeological site. The excavations that took place here during the 90s brought to light fragments of the ancient capital of the island, which was continuously inhabited from the 10th century BC till the 6th century AD. A shrine dedicated to the goddess Demeter used to stand at the top of the ancient acropolis. The ruins of two large rectangular buildings of the 4th century BC have been discovered a bit lower, on a plateau along the brow of the hill. At the northern edge of the same plateau, another temple has been found. During the second excavation phase after 2002, two altars and a temple with its sanctum intact were also unearthed. Many votive offerings of the Archaic Period and jewels were discovered, as well. The temple seems to have been dedicated to Apollo and Artemis, based on inscriptions and jar fragments found at the site.    

In the 6th century AD, when Vryokastro, the ancient capital of Kythnos, was abandoned for good, the inhabitants carried their belongings to an even steeper location, on the heights of Katakefalo, which they also fortified. During the Venetian rule, this fortified city that was said to have had 100 churches at that time flourished. Only two of these churches still stand today: Agia Triada and Agia Eleousa (or «Keraleousa»). The latter is in better condition. According to local legends the castle of Katakefalo and the Castle of Oria are one and the same. Popular songs about the Castle of Oria narrate how it withstood an Ottoman siege for «twelve years» and that when it finally fell – as a result of betrayal – the blood that was spilled reached the coasts of Kea. The hiking trail towards the castle begins 3.5km north of Loutra. The castle is accessible through a difficult dirt road that quickly turns into a path. The imposing landscape makes quite an impression on every hiker from the start. The legends seem to come to life thanks to the whimsical cliff formations, the wildness of the precipice and the gradual expansion of the view towards the rest of the island and the open sea.