After the death of Matilda of Canossa in 1115, Mantua becomes a free commune and strenuously defends itself from the Holy Roman Empire during the twelfth and thirteenth centuries.

In 1198, Alberto Pitentino alters the course of River Mincio, creating what the Mantuans call "the four lakes" to reinforce the city's natural protection.

Three of these lakes still remain today and the fourth one, which runs through the center of town, will be reclaimed in the eighteenth century.