Argostoli is a town and a municipality on the island of Kefalonia, Ionian Islands, Greece. Since the 2019 local government reform it is one of the three municipalities on the island. It has been the capital and administrative centre of Kefalonia since 1757, following a population shift down from the old capital of Agios Georgios, also known as Kastro, to take advantage of the trading opportunities provided by the sheltered bay upon which Argostoli sits.