- The actual site of the fort was established by the Acheans during the Mycenaean epoch (1400 — 1100 B.C.).
- Around 700 B.C. the Spartans positioned allied peoples with the Intention of monitoring their conquests, transferring them to the city of Assini, which possessed its own acropolis with pre-classical edifices similar to those of the temple of Apollo. In addition, the church of Aghios CHARALAMBIS would be built over the temple of ZEUS
- The wars of Messenia against Sparta, which lasted nearly four centuries, do not give us much idea as to what life in Assini was like.
- During the Byzantine era, towards the 5th century, KORONI, ancient EPIA (current location of PETALIDI) was moved for reasons of security to ASSINI. KORONI took thereafter the place of ASSINI and continued peacefully as a Byzantine province.
- The Byzantines reinforced the remparts of the ancient acropolis and built Byzantine edifices with neoclassical, pagan materials.
- The decline of Byzance — Constantinople, allowed the Francs to take possession of the Fort in 1204, transferring it to the Venetians peacefully in 1207.
- The new occupants built the fortress over the ancient acropolis, over a sketch of 40 hectares with materials recuperated from the neoclassical (Frankish and Byzantine) edifices.
- A victim of its dominant position, the fort was the object of bloody assaults inflicted by Frankish, Turkish, Venetian, Genoan and Spanish pretenders.