From the middle of the 14th century, the building underwent a series of changes .
In the 15th century the porticoes were built and in 1472 the clock tower (Torre dell'Orologio) was built from a design by architect Luca Fancelli.
The following year a clock was added to the tower. Conceived by mathematician and astrologer Bartolomeo Manfredi, the clock communicated the time to the people, the position of the planets , dawn and dusk, the signs of the zodiac, phases of the moon, the days favourable for bloodletting , sowing, departing on journeys and other things "useful in this world". The clock was certainly still functioning in the early eighteenth century. It was later made into a normal clock mechanism showing the sun and the hours.
In 1700, architect Doricilio Moscatelli closed the 13th century triple lancet windows, replacing them with wide windows that let in a great deal more light.
At the beginning of the 20th century, the original characteristics of the palazzo were restored by local architect Aldo Andreani, who eliminated the Baroque additions.
Used for centuries for the administration of justice, in 1997 it became a splendid home to exhibitions by the civic museums of Mantua and has hosted numerous important art exhibitions organized by the Municipality.
Visible on the end wall in the huge hall are the remains of some fine frescoes representing war scenes dating from around the end of the 12th century. Also present are holy figures painted by Grisopolo of Parma , which can be dated to the mid 13th century. Various shops and restaurants are housed under the porticoes at street level.