The most important site in times is Vryokastro of Rigokastro, as it is called today; it is on the NW side of the island and according to the ancient sources it was called Kythnos.
The surface research in 1990 – 1995 brought to light many findings and the town planning and the residential organization of the town were clearly identified.
According to the findings it was constantly inhabited from the 10th century B.C. to the 6th – 7th century A.D.
Among the numerous findings, there are sepulchral bas-reliefs, sculptures, architectural findings inscriptions, shards of archaic jars with bas-reliefs, the Attic pottery of archaic and classic ages, sealed handles of trading amphoras and so on.
Taking into account the surface pottery, the town was abandoned in the 6th or 7th century A.D. When the residents moved to the fortified settlement in Oria Castle.