The vestibule is the anteroom leading into the main apartment. The entrance is via a splendid door made of white Carrara marble from a glass-sided hall preceded by a marble staircase. It has a circular plan for which Valente was inspired by the Rotonda in Vicenza designed by Palladio.
The vestibule has a marble-tiled floor and leads to the rooms on the ground floor and, on the right, to a large staircase that leads up to the first floor. It is overlooked by a round balcony illuminated by a skylight.
The four curved benches set against the walls with niches decorated in stucco containing Japanese vases are an integral part of the furnishings.