Historically subjected to Genovese domination, Carrosio is mentioned for the first time as a sensitive military site in 1624, when the Savoyard engineer Carlo Morello was charged with an espionage mission to acquire information about Genova’s walls and the streets of Oltregiogo.
The small village passed to Sardinia’s control, along with Serravalle, Tortonese and the feudal domains, thanks to the 1738 Vienna Treaty, becoming a real enclave within the Genovese region. It is hardly surprising then that, in the months that followed, a detachment of the Piemonte Fanteria regiment were charged with the control of the road.
The site’s fortification can undoubtedly be associated with this context, although some chronological data is missing. Following the latest outbreak of fighting for control of the Bocchetta road, an inspection was carried out in 1763 and a plan drawn up. This shows the profile of a curtain wall on the west side of the town, the shape of which would undoubtedly qualify as “modern”. At that time, however, the cliff-top structures over Lemme were not yet present; in all probability, these structures would have began construction in 1769, or when the decision was made in Torino to deploy a new contingent of troops to Carrosio.
