The ducal palace was the government building of Sabbioneta Duchy. They built it in 1560-1561, after a fire destroyed the previous structure. It is a four floors building, and it was the residence of duke Vespasiano Gonzaga.
The façade has a five fornices rusticated porch and a white marble staircase; it is crossed by a moulded stringcourse, while marble tympanums stand over the windows. The writing VESP. D. G. DVX SABLON. I.  – id est Vespasiano first duke of Sabbioneta by the Grace of God – decks the architrave.
Five marble busts, depicting Roman emperors, stand over windows tympanums. A Leone Leoni’s bronze statue of duke Vespasiano, which today is in Incoronata church, was once on the right side of the staircase. A small bronze loggia once stood over the central balcony.
In 1584, Bernardino Campi and Michelangelo Veronese frescoed the upper part of the façade.