Kefallinía (kĕfälēnēˈä) [key] or Cephalonia sĕfəlōˈnyə, island (1991 pop. 29,392), c.300 sq mi (780 sq km), W Greece, the largest of the Ionian Islands. It has an irregular coastline and is largely mountainous, rising to c.5,340 ft (1,630 m) at Mt. Ainos, which in ancient times was crowned by a temple to Zeus. Argostolion, a port, is the island's main town and ships local products such as fruit and wine. Sheep raising and fishing are important occupations on the island. Kefallinía was an ally of Athens in the Peloponnesian War and later was a member of the Aetolian League. The island was taken by Rome in 189 B.C. After the division of the Roman Empire (A.D. 395), it was held by the Byzantine Empire until its occupation (1126) by Venice. It subsequently was ruled by several Italian families, was seized by the Ottoman Turks (1479), and was ceded (1499) to Venice, which held it until the Treaty of Campo Formio (1797). Its subsequent history is that of the Ionian Islands. In 1953 the island was devastated by earthquakes of such force that Mt. Ainos was split.