Thyrrheion was probably built in the 5th century BCE from colonists from Corinth. During its time, it was one of the chief cities of Akarnania and would eventually be one of the seats of the Akarnanian League.
Xenophon mentions them as being “very valiant men” and in possession of a very strong fortress. Little is known about it during the time of Alexander the Great other than it was a strong trading town with two ports. It initially prospered during Roman times until its inhabitants were moved to Nikopolis under orders of Augustus.
The ruins are in good shape and the ancient walls, at 10km, are among the longest in Greece.