The Mantuan Serraglio represents one of the most important defensive complexes in the Mantuan plain, with a history that intertwines military fortifications, hydraulic control of the territory, and urban planning. Its first significant depiction comes from the fresco of the Masseria di Mantova, discovered in October 1981 during renovation works in spaces formerly belonging to the so-called Masseria del Comune, where the town’s incoming and outgoing records were kept.
The fresco, dating to the first half of the 15th century, depicts the city of Mantua and its defenses, including subordinate fortifications across the territory. Likely commissioned shortly after Gianfrancesco Gonzaga was granted marquisate dignity by Emperor Sigismund (circa 1433), the work celebrated the power of the new lord and the strength of his lineage. The frescoed images highlight military might with castles, towers, and small forts (rocchette), stretching continuously from Curtatone to Montanara, Buscoldo, and Borgoforte. Unfortunately, the depiction of Governolo and the surrounding area along the lower Mincio has been lost.
The fresco emphasizes the martial dimension of the fortifications: battlemented towers, tall turreted structures, symbolizing strength and defense. Among the most notable structures were:
- Porta Aquadrucio, later called Pradella, marking the start of the northern embankment/road of the Serraglio.
- Curtatone Castle, with a keep featuring a wooden upper structure, probably a bell chamber.
- Rocchette of Montanara and Balcantono, southwest of Curtatone, located along the Curtatone moat.
- Buscoldo, with a castle, intermediate tower, and the Bussi small fort, in a marshy and valley environment offering natural defense.
- Borgoforte, on the Po River bank, with castle and small forts of Frassinello and Saviola, forming an integral part of the Serraglio.
Curtatone, in particular, held a strategic role along the road from Mantua to Cremona. In addition to the main castle, historical maps indicate a tower/fort (rocca) on the Osone River, located north of the watercourse near its outlet into the Upper Lake. This structure controlled access to the area, analogous to the Osone rocchetta of Montanara. The main castle of Curtatone, on the other hand, had an extended defensive wall and served as a residence; 14th-century documents record restoration works on the moats after destruction by Bernabò Visconti in 1357, including detailed measurements of curtain walls and defensive ditches.
17th-century maps show Curtatone Castle with reduced defenses, but with the keep still present, accompanied by the tower/fort on the Osone, overseeing the road to Mantua. The entire Serraglio system thus combined military function with hydraulic control, using moats, canals, and watercourses to protect the city and its communication routes.
Today, the Mantuan Serraglio remains an extraordinary testament to territorial defense and hydraulic planning, able to convey, through frescoes and documents, the evolution of military strategy and urban life from the Middle Ages to the Renaissance.