Cos or Kos (Ancient Greek: Κῶς) was a city of ancient Greece on the island of the same name.[1] In 366 BCE, the inhabitants of the town of Astypalaea abandoned their town to populate Cos.[2][3] Cos was a member of the Dorian Pentapolis, whose sanctuary was on the Triopian promontory.[4] Under the Athenian rule it had no walls, and it was first fortified by Alcibiades at the close of the Peloponnesian War.[5] In subsequent times it shared the general fate of the neighbouring coasts and islands. Antoninus Pius rebuilt the city, after it had been destroyed by an earthquake.[6]
Its site is located near modern Kos.[1][7]