After Constantinopolis was conquered by the Francs of the 4th Crusade, in 1204, Crete was given to Bonifatius of Monferrat; this latter sold the island to the Venetians. However, before the Venetians arrive and take possession of the island, in 1206 the then famous Genovese pirate Enrico Pescatore occupied the island and started to fortify it in order to resist well to the Venetians' attempt to regain it.

One of the most important and well known castles of this period is that of Monopari, near the village Valsamonero, some 17 kilometers far from Rethymnon to the South. Ruins of the castle of Pescatore still stand on the hill of Kastellos.

The place is a natural stronghold, as it is inaccessible from all directions apart from the Northern, and thus it is only there that a defensive wall had to be constructed.

Today, only a few ruins of the walls with defensive towers protecting the entrance gate, along with the ruins of some buildings are visible.