Important discoveries are the board of Hellenistic wall, that confirm the suggestion that on this position was the ancient Greek city Herakleion and the gate in the wall of the donjon. The core of the city Herakleion remains to be found, but it is posited that it is located on the northwest side of the castle’s hill due to shells and coins found during recent excavations.
The castle – its greatest part at least- was built by the Franc king of Thessaloniki, Bonifacius e Monferèt, in 1205, upon a Byzantine castle that had previously existed there, as parts of its castle walls -dating from the 6th, 9th and 10th centuries- confirm. During the years 1218-1224 AD, the castle was seized by the Duke of Hepirus, Angelos Komninos, who gave an end to the Franc Occupation in Thessaloniki in 1224 naming this city the capital of the Byzantine Empire.
The Castle of Platamonas was conquered -about in 1389- by the Turks, who, thus, could have the overall control over the “passage” of the Valley of Tempi, leading to Southern Greece. Later on, nevertheless, while Mourat was encirclinf the Bay of Thermaikos, the Venetians took over the administration of Thessaloniki in 1423. The castle of Platamonas was fortified, then, on a parallel with the fortification of Cassandra, Chalkidiki, so that control over the entire Bay of Thermaikos would by possible.
During the years of the Turkish Occupation, the Castle of Platamonas was considerably fortified very early, owing to its strategic position and the commencement of the nationalistic liberating movements and recolutions taken up by the Greeks, the epicentre of which uprisings being the Olympus. Even more, Captain Lazos’ son -coming from the district of Olympus-, John, managed to conquer the castle after a row of tremendous battles against its Albanian defenders.
When, later on, Southern Greece was liberated and Thessaly was attached to it (1881), the Castle of Platamonas at the Greek-Turkish of that time, regained a new and consederable significance for the Turks. Nevertheless, it was abandoned afterwards as its defence would be of no avail to the conquerors.