The castle is the building which characterises the appearance of the town of Desenzano, either when seen on arrival from inland, or when seen from the port, or even further away, from the lake. At the end of the fifteenth century the castle, which has its origins in the High Middle-Ages and probably stands on the foundations of a Roman castrum, was extended towards the south; however, it never became a military fortress, although the extension was carried out in order to house a garrison. It still continued its major role as a refuge for the population.

Inside the castle there were the private homes of a few citizens which were always ready to accommodate those who lived outside the castle walls in the event of danger. In later years the castle gradually surrendered its function as a refuge, families continued to live there although its deterioration throughout the nineteenth century grew steadily worse. In the castle there was even a church, the church of St. Ambrose, which was used as a private house. The layout of the castle is that of an irregular rectangle, with a tower rising up at the entrance, on the northern side, protecting the drawbridge, of which the loop-holes for the chains can still be seen today. It is a square-built tower with a single window in the upper part.

In 1882 the castle was used as a barracks, first as the headquarters of an infantry garrison, then for Bersaglieres and finally for the Alpine troops from the thirties until 1943. The old castle, although devoid of any particular architectural beauty, apart from the façade, is undoubtedly of great historical interest and of spectacular charm. All that remains of the old castle are some lengths of defence walls with crumbling merlons between the four cut-off towers, with the exception of the one on the north-eastern corner which up until 1940 was used as an observatory. From its terrace you can enjoy one of the most beautiful views of Lake Garda.