Ancient Greek Mosaic Ruins. Kos Island's Landmark. Close To The Asclepeion And Ancient Gymnasion, Greece. Royalty-Free Stock Photography

Cos or Kos (Ancient Greek: Κῶς) was a city of ancient Greece on the island of the same name. Inhabitants of the town of Astypalaea abandoned their town to populate Cos. Cos was a member of the Dorian Pentapolis, whose sanctuary was on the Triopian promontory. Under the Athenian rule it had no walls, and it was first fortified by Alcibiades at the close of the Peloponnesian War. Ruins of the Ancient Gymnasion. View of the Asclepeion. View of the ancient Odeon