The island of Kefalonia, usually known in English as Cephalonia and also known as Cephallenia, Cephallonia, Kefallinia, or Kefallonia, is the largest of the Ionian Islands in western Greece, with an area of 781 square kilometres (302 sq mi). It is also a separate peripheral unit of the Ionian Islands Periphery, and the only municipality of the peripheral unit. The capital of Cephalonia is Argostoli.