The Spanish military occupation of the Finale from 1602 led to a radical change in the landscape which was brought about by the construction of large modern fortifications meant to transform the ancient marquessate into a powerful stronghold wedged among the dominions of the Republic of Genoa.
Castel San Giovanni was erected on the ridge of the Becchignolo hill above Finalborgo: from whence it was possible to control both the borgo and the roads to the Bormida and Langhe valleys.
The part of the walls that climbed along the westerns foot of the hill was interrupted by the Mezzalama Gate. The road built by Engineer Gaspare Beretta in 1666 that went through this gate connected Finale to the Duchy of Milan.
Ferdinando Glazar, who originally came from Carinthia but worked for the Spanish in the Finale area, supervised the construction of a new round of walls between 1640 and 1644.
The new walls included the pre-existing medieval tower connecting different sections of wall. The original tower can still be spotted in the central octagonal building, surrounded by the curtains of the Spanish fortress.
Re-furbished again between 1674 and 1678 by Beretta, the stronghold was able to accommodate the irregular profile of the hill because the round of walls was sectioned into ramparts.
To the south and dominating the Borgo as well as the view to the sea, the walls are characterised by two powerful pincer-shaped bastions with steep escarpment-like buttresses, surmounted by a sentry box on each corner.
The entrance that opens directly onto the Perti road is protected by a set of ravelins, which are set lower down if compared to the fortress’s curtains. The only surviving parts are the original defense system provided with hanging brackets and parts of the draw-bridge over the narrow moat, which enabled access to a square factory building.
After 1713, the Republic of Genoa reduced the building by knocking down the north wing.
In 1822 it was turned into a prison, then after a lengthy period of disuse, the building was completely refurbished between 1985 and 1991.