The historic fortress of Paleokastro played an important role in the protection of the Fraskia bay and the entire bay of Heraklion during the last years of Venetian Domination in Crete.

In the early years of their domination, the Venetians had not placed much emphasis on the fortification of this region. However, when the danger of the Ottoman Empire began to grow, the need for some kind of fortification in the area became even more urgent, as it was evident that the western bastion of St. Andrew and the ships of the Republic of Venice could not provide an adequate defense to the city of Candia.

So, the Venetians decided to build a new fortress, which, along with the Koules fortress, would help to defend the shores of Candia. Access to the entrance was made from the south side, climbing a few high steps that had been scattered over the rock. Due to its excellent strategic position, the Ottomans faced enough difficulty paving the way for the fall of Candia.