The Valchiavenna is an Alpine valley, once strategically important as route across the Alps, past Lake Como to Milan.

During the War of the Austrian Succession, Count Giovanni Serbellone, military governor of the county, was tasked with fortifying this area; this plan, drawn by the military engineer Giulo Magnoni and engraved by Giovanni Paulo Bianchi, depicts the works constructed, linked to a letterpress key pasted below.