The antechamber and the alcove were the first interiors to be renovated by Giovanni Battista Mazzetti, for his marriage to Elena Caterina Ponte di Casalgrasso in 1684. The occasion seems to have inspired the decorative motifs of entwined wedding rings and a heart pierced by an arrow, set at the base of the alcove pilaster strips.

The exuberant stucco decoration features themes typical of the Baroque style: caryatids, ribbons with hanging fruit, and well-modelled telamon busts of an elderly and a young man with expressive faces, supporting the arch impost surmounted by the Mazzetti coat of arms.
The fresco of the figure of Flora crowned by Love by Anacleto Laretto (Grana 1874 – Asti 1950), dates to 20th-century restoration work (1939), while the mural of Diana and Endymion, on the back wall, is a late 17th-century decoration. Again, here, the works on display come from groups of collections donated to Museum in the 20th century.

The gilded wooden console, large pier glass and the living room suite (part of which is in the antechamber), comprising a pair of sofas and 13 chairs, are of 18th-century Piedmontese production. The ebony veneer wooden chest with ivory inlay is attributable instead to a Lombard workshop and is dated to the second half of the 17th century.

The lavish carved frame of the fireplace pier glass is fitted with ancient mirrors but is an imitation of a 19th-century Piedmontese Baroque model.