According to some, the Phoenicians are regarded as the founders of the city and probably introduced the worship of Aphrodite Megonitida. When Pausanias visited Gythio he recorded an old tale according to which Heracles and Apollo were the founders of the city after the end of a fight over a delphic tripod, stolen by Heracles.
Following the Doric conquest, interest in Gythio ceased. The Spartans fortified both the port, and later the city, frequently attacked by Athenian forces. Around 455 BC the Athenian admiral Tolmides seized and destroyed Gythio so as to prevent the Spartans naval development but the Spartans fortified the port yet again. Both Epaminondas in 369 BC and Philip V of Macedonia in 218 BC failed in their attempts to capture the city.
Gythio as rebuilt later by Nabis and in 195 AC was felt to the Romans after a seige. Titus Flaminius set up a confederacy (Lakedaemonian's Common) made up of Gythio and other coastal towns which changed its name to Free Lakonians Common during the rule of Augustus. From then on Gythio set out to become not only an important commercial centre but also a port renowed for the progress and exportation of porphyry.
The city's prosperity lasted till the 4th century. It was resancked by the Goths in 395 AC and finally deserted.
In 1687 it was resurface again, as a small port. In 1770 it was known as Marathonisi, and was a major centre of the Greek Revolution and the most important city of the free-Lakonian League. After the outbreak of the revolution of 1821 the Gregorakis family, members of the Filiki Eteria, raised the flag of revolution on Marathonisi on March 23rd thus making it the Greek fleet operations centre. In 1830 Gythio raised against I. Kapodistria. In 1852 the inhabitants stood firmly behind monk Papoulakis movement mainly because they opposed King Otto 's government. In 1934 Gythio revolted against the Bavarians who wanted to demolish the traditional towers of Mani.
Today represents the capital of Mani the isolated southern fringe of the Peloponesse named after Maina castle, built by William de Villehardouin in the 13th century. It is the second largest city (4600 inhabitants) in Laconia after Sparta and the seat of an eparchy. From August 1997, Gythio is affiliated with the french city Villeneuve Les Avignon. Olives, olive oil and valonia are its chief exports. It has a pleasant promenade with pastel - coloured buildings chambering up to the steep wooded hill of Koumaros. Gythio boasts beautiful sand and stone beaches, picturesque houses, friendly and affable people.
Informations from the Roman-Germanic Central Museum about The harbour of ancient Gythio