It is built in the summit of a small hill located 4 kilometers to the north-west of the port of Pothia and it is an individual castle that was used as an observatory. It was known as Hrysoheria, Pera Kastro and Hrisoserza. Inside the castle there were tanks and other buildings, while under the hill there were three cone-shaped windmills that were enclosed by circular walls with openings used in case of war. These windmills can date back to 1522. At the walls of the semicircular tower of the castle’s south part there are saved coats of arms belonging to Fantino Querini, the commander of Kos, and to the Great Magister Jean Bonpart de Lastic (1437-1454). At the south wall, there are coats of arms belonging to the Order of Saint John and the knight Giacopo Geltru, the commander of Kos after 1466.
In the area Emporios, there is the known area Kastri, i.e. parts of cyclopean walls with their tower up on a steep mound.
In the area Massouri, in “Kasteli” there are the remains of a Byzantine castle. At this point, we should mention the existence of a legend concerning the young prince of Kasteli who was in love with the young princess of the opposite castle situated in Telendos.