The gallery’s decoration is based on themes like royalty and imperial power, with depictions of the rural world and the Commedia dell’Arte.
There are actually two periods of decoration: the first is dated 1722 and includes 12 profiles of Roman emperors by Ticino artist Antonio Catenazzi, while the 1728 gilt stuccoes and marbled pilaster strips are by Marsilio Roncati di Meride.
The style recalls the art of the stucco workers engaged by Jeanne of Savoy for Palazzo Madama in Turin from 1690, and the animated geometric weavings of peasant figures, masks and animals reveal influences inherited from French artist Jean Bérain.
In 1728 the gallery was completed with celebratory frescos and gildings, but the theme of the painting appears linked to the important event of the preceding spring, when Giovanni Battista Mazzetti hosted the Prince of Piedmont (the future Charles Emmanuel III of Savoy).
The vault frescoes depict, respectively, the young warrior prince on a chariot drawn by lions and the glorification of the Mazzetti family.
The paintings are by Bolognese artist Giovanni Antonio Caccioli. On the back wall, the bust of Giovanni Battista is set above the plaque declaring the end of the works (1730). Ovals depicting the family of King Victor Emmanuel I of Savoy date to the Restoration period, as do ceramic and enamelled, gilt metal appliques.
The three consoles have striking Sicilian jasper shelves.