The coat of arms of the Archinto, Arese, Visconti, Omodei, Odescalchi and Borromeo families are displayed on the north wall while the family crests of the Legnani, Cusani, Opizzoni, Gallarati, Melzi, Marliani, D’Adda, Corio, Pettenari and Scanzia families are present on the east wall.
The adjacent south wall contains, among other things, the coat of arms of the Arconati and Ghisolfi families, in addition to the emblems of the King of Spain and the Duke of Milan. Finally in the west wall, the emblems displayed are those of the Castiglioni, Panigarola, Natta, Caravaggio, Cavenago, Simonetta, Pirovano, Tornielli, Lampugnani, Lurani, Porro, Scotti, Tolentino, Monti, Visconti Borromeo, Grillo, Caccia and Odescalchi families. Among the family crests, many remember the coat of arms of the Omodei and Borromeo families, which are characterized by the presence of a cardinal’s biretta, and that of the Odescalchi family, topped by a tiara, a testimony of the high ecclesiastical offices exercised by the kin of the Arese family. Bartolomeo Arese had indeed married Eleanor Omodei, sister of Cardinal Luigi Omodei: this marriage produced a son, Giulio, and two daughters, Margherita and Giulia, who respectively married into the Visconti and Borromeo families. The effigy of the Cusani family is also remarkable, with five gold points and four green ones, topped by an antique gold crown painted in honour of the marriage of Elizabeth Cusani to Giberto V Borromeo Arese, the last of the descendants of Bartolomeo who carried out the works inside the building.
On the south side is a monochrome depiction of the Allegory of Astronomy, which symbolizes the proximity with the observatory, framed by an architectural partimento that is a painted window with a farmer holding a two-pronged pitchfork and wearing a slouch hat, looking out of the painting. This figure introduces a well-represented series within the palace that is of the so called “characters” (real people) inserted into solemn family history to link the glory of the Arese family to everyday life with irony, but only up to a certain point, through the potential offered by the pictorial illusion. The farmer could represent, therefore, the lord of the house, which in this way welcomes those climbing the stairs; he is depicted holding a pitchfork, symbol of the supervision of animals and represented by the two prongs attached to a ferrule where one can catch a glimpse of a wooden handle. By presenting himself in peasant garb, the lord of the palace cannot help but emphasize his governing power, under which all are bound to comply. In addition to the symbolism in the heraldry, there are numerous iconographic elements concealed in the frescoes of this staircase. One which stands out the most for its originality is the presence of a chained monkey, painted on the west wall. This represents, not so much the victory of the famous family over evil, but rather, the possibility that those who abandon themselves to unbridled instincts and the sin of being educated, may be saved if they adhere to family traditions. In fact, in the painting of the 16th-17th centuries, the monkey abandons his association with evil to become an image of man who has fallen into a state of profound decay and needs someone to save him. If it is then the Virgin Mary who was given this task of redemption as in the painting, “Our Lady of the Monkey” by Albrecht Dürer, at Cesano this task was given to the nobility and aristocracy of Lombardy, that offered to act as society’s educator, capable of discerning good from evil and enchaining men who indulged in excesses.
Furthermore, there are two dates painted on the grand staircase: 1659 above the lower entrance, and 1663 above the door of the antechamber which leads to the south wing, intended as a chronological reference to the symbolic completion of the entire building within five years.