Evidence of this includes a mosaic (now preserved in the Civic Museums) and other artifacts dating back to the fourth or fifth century found during the restorations carried out between 1926 and 1928[2] First the south wing of the building was built, immediately followed by the east one, historians believe that this happened around the last two decades of the 12th century, as evidenced by an inscription preserved in the Civic Museums.

[3] In 1236 the northern part, overlooking Piazza Vittoria, and the east were added, so as to create a large courtyard inserted within the three wings of the complex.

Similarly to other municipal buildings in northern Italy, these structures had arcades on the ground floor, of which there are traces in the facade that closes the courtyard of the broletto to the south.

Starting from the first decades of the fourteenth century, a smaller political body was created, the Council of the Twelve Wise Men, which met in the podestà's room.

[5] In the Visconti age the complex underwent several interventions, such as the transformation of some windows (enriched with two-tone frames), the partial closure of the ancient loggias on the ground floor, while, at least from 1398, in the southern wing of the building, the one overlooking Piazza Cavagneria, prisons were created.