The castle is built on the site of ancient Heraklion (or Heraklion).
In Periplus of Pseudo-Skylakas (4th century BC), it is referred to as "the first city of Macedonia, Heraklion".
Recent excavations have brought to light ceramics of Euboean, Early Corinthian, and geometric times from Eastern Greece, which show the presence of Greeks as early as the 8th century. B.C.
The name Platamonas was first mentioned in 1198 by a golden bull by the Byzantine Emperor Alexios Komninos I.
After the Fourth Crusade (1204), with the entry of the Franks into Greece, Pieria was granted (as part of the Kingdom of Thessaloniki) to Boniface the Confessor in 1204.
The castles of Citrus and Platamon were given to his knights.
The castle of Citrus was taken by Vriich von Down and the Lombard Rolando Pike or Piscia was taken by Platamon.
The latter built the castle there, sometime between 1204 and 1222, by order of Boniface, at the site of the Byzantine fortification, in order to control the passage from Macedonia to Thessaly.
Latin churches were also founded in Platamonas and Citrus, with a Catholic bishop (in Citrus the Catholic diocese would last until the conquest of Macedonia by the Turks in the late 14th century).
There is a reference in the Chronicle of Moreau
Around 1224 Platamonas Castle was occupied by Theodore I Komnenos the Duke, when he overthrew the Franciscan Kingdom of Thessaloniki.
The castle was then controlled by his brother, Manuel Komninos Doukas. It was then annexed to the Despotate of Epirus by Michael Doukas.
After the Battle of Pelagonia (1259), he was captured by the Emperor of Nicaea Michael VIII the Palaiologos and served as a prison for the Franks who had been captured in that battle.
Platamonas will be re-used as a prison for the Zealots revolutionaries in 1345, when they were defeated by the Apocalypse.