St. John's Castle was built in order to strengthen the defenses by the Spaniards from 1640 to 1644 on the ruins of a tower dating back to the half of the XV century. This tower (remembered by Gianmario Filelfo and of which we have news from a drawing of 1571), today constitutes the central body, octagonal in plan, of the fortress.
Much more recent than the near Castel Gavone, constituted a advanced defense and simultaneously protected and controlled Finalborgo is the capital of the Marquisate of Finale. Was often restored and expanded in its domains by the Spanish between 1674 and 1678, led by engineer Gaspare Beretta, which occupied the direct connection with the village and reinforcements of the fortifications. It was abandoned in 1707 and in 1713 ceded by Austria to Genoa, that the demolished in part. In 1822 it became a prison and then from 1960 was forfeited by the state property and in recent years entirely restored.