The Knight Castle was built in 14th century on the ruins of an oldest fortress. The castle has two rounds of walls and it used to be surrounded by water and connected to the mainland by a bridge.Over the main gate one sees a Hellenistic frieze with masks and garlands. On the central gate, known as the Carmadino gate, there are basalt columns placed obliquely, which came probably from the early Christian era. A huge, old plane tree, known as the Tree of Hippocrates stands in front of the castle; according to legend, Hippocrates, the father of Medicine, used to sit under this plane tree and teach his students.
Marina Kos is located on the outskirts of Kos town; about 15 min walk from the town center, next to Kos old harbour. Marina Kos is easily accessible, only 26Km away, through Hippocrates International Airport (IATA: KGS) by charter flights from the major European cities.
Lake Psalidi is near Kos town and is a great destination for bird-watching, providing birds such as rare ducks and flamingoes. Some of the species, which could be found there, especially in the autumn, include Reddy Shelduck, Slender-billed Curlew, Long-legged Buzzard and Lesser Kestrel.
The Archaeological museum of Kos is located at Eleftherias square, in a neoclassical building, designed in 1935. Excavations brought to light findings by the beginning of the century, mainly from the archaeological site of the Market and also from monuments, such as, the Altar of Dionisos, the Odeon and the Roman Residence.