Thanks to its position the fort has a vast view of the surrounding valleys and of the historic centre of Finalborgo, from which is distant only 500 m and can be reached on foot along the Beretta road. The road was built in the same years and from Porta Mezzaluna climbs up the ridge to Castel Gavone and linked the area to the duchy of Milan.
Modernised and widened during the 17th century San Giovanni fort was partially demolished in 1713 by the Genoese and, after a period of abandonment, in 1822 was used by the Savoia government as a prison, activity that it maintained until the beginning of the 20th century.
Its current appearance is due to the restoration work carried out at the end of the last century.
Fitting perfectly in the landscape the fort is characterised by the presence of watch towers in the corners and by the tall pincer walls of the southern front.
The entrance to the complex is on the north side and immediately meets a two-story building with the prison cells (on the slates around the doors 18th century graffiti can still be seen, sketched by the prisoners). At the centre of the complex there is the central tower, the “main tower”, that incorporates the pre-existing medieval tower, while on the southern side there is a building that is set on three levels, of which the lowest one faces directly the parade ground of the fort.
All of the spaces of the fort can be visited, including a small chapel and an ancient kitchen in which the fireplace can still be seen in the wall; from the terraces and the openings in the watch towers one can see various different views of the surrounding territory.