The north and east sides of Piazza Grande are bounded by an L-shaped arcaded building which houses some of the city council offices. The site is that occupied by the seat of the medieval city government, which consisted of two separate buildings that had grown up side by side, the city offices and the law courts. From the square, no trace of these older structures is now visible, since they were masked in the XVII Century by the arcaded facade which combines the two original palazzi into a single whole. High up on the end of this arcade, on the corner overlooking via Castellaro, stands the statue known as the Bonissima, another symbol dear to the hearts of the people of Modena; in fact, local personalities well known to the town are said to be "as famous as the Bonissima". The strange thing is that no-one knows what the female figure represents; one theory is that the name derives from the Ufficio della Bona Estima (later contracted to Bonissima), or Weights and Measures Office, in front of which the statue was placed in 1268 on a piece of marble supported by four pillars carved with the standard measurements, as symbolic guarantrix of fair measures. However, the popular imagination prefers another explanation, involving a very rich lady known as "Bona" or "Good", who spent generously to help the poor.

Another trace of charitable care for the people of Modena (if only those selling their wares in the square) is the "Sala del fuoco" or "Fire Room" inside the Palazzo Comunale; according to tradition, the name derives from the fact that the fireplace still in the room was used during the winter to produce hot embers which were then transferred to the stallholders' braziers to help them bear the cold conditions. As well as the large marble fireplace, the room is also of interest to the visitor by reason of its coffered ceiling and the paintings on the walls by Nicolò Dell'Abate (1546) which show Brutus's siege of Modena in 44-43 B.C. in the campaign against Mark Anthony. The pictorial decoration of this and adjoining rooms reflects the city governors' efforts to support the most solid civic virtues with strongly symbolic messages; the classical theme of Nicolò Dell'Abate's sophisticated Renaissance work is an opportunity to underline the greatness of Modena's ancient "Municipium". Next door, in the "Sala del Vecchio Consiglio", the old Council Chamber, paintings illustrate other classical Greek and Roman themes, all strictly related to civic virtues. The ceiling of this room, already XVII Century in taste, offers the people of Modena examples worthy of imitation, including Coriolanus allowing himself to be persuaded not to attack Rome in the interest of his country, and the Theban Menecius throwing himself from the walls of his city in order to fulfil the prophecy that his sacrifice would save Thebes. A century and a half separates decorations of the Sala del Vecchio Consiglio, or Old Council Chamber (early XVII Century) from those of the Sala degli Arazzi (Tapestry Room), but the scenes portrayed are still intended to praise civic virtues and the independent identity of city states. Three walls illustrate the birth of city powers, with scenes of the treaty of Constance (by which Frederick Barbarossa granted wide territorial independence to the Italian city states) and of the heads of local communities paying homage to the city ruler. In Modena, in the two buildings which most clearly reflect civil and religious power (the City Hall and the Cathedral, both overlooking Piazza Grande) decorations are used to serve a dual purpose: they give the insides and outsides of the walls solemn grandeur, while also using symbols to instil civil and moral virtues in the citizen and the believer.