In a distance 3.5 kilom. northwest of Kos town, at the slopes of a low mount with a view at the coasts of Asia Minor, there is the monumental complex of Asclepio. The space was located in the beginnings of 20th century by the German archaeologist R. Herzog and the research continued later Italian archeologists who attempted, and the restoration of the monument projecting mainly to the Roman side. The complex is extended in three mounds. At the lowest a gallery at Π shape (3rd century b. C) that today is maintained in level of foundation,

The castle of the Knights of the Order of Saint John is situated at the entrance of Kos harbour on what used to be an island in antiquity, communicating with the inland through a bridge that one can still see even today namely the bridge of “Phoinikon" (Palm Trees) Avenue. The castle consists of two defensive precincts. The interior one has four circular towers in the corners; the south-eastern tower forms part of the exterior precinct, which is the larger one of the two, with massive bastions on the four corners, battlements and gun ports.