Besides Kastro, the most important archaeological sites of Kythnos include Vryokastro, the ancient 10th century B.C. capital on the norteastern coast. There are the remains of some walls and towers and two Hellenistic temples. Little remains of the ancient site of Kastellas but the site of Maroulas, perhaps the oldest site in the Cyclades, has the remains of some buildings from the 8th and 7th Century B.C.
archaiological site of Kythnos-named Vryokastro, Kythnos 840 06