The Chapel is dedicated to the Purity of the Virgin Mary, well represented in the picture above the altar in the act of watering a lily, having the Parents alongside: S. Anna and S. Gioacchino. Under the altar the relics of S. Felice Martire child are venerated, and in the lateral niche to the right of the altar the S. Calocerio bones were moved and entrusted to the Provana in remote times, coming from the catacombs of Rome.

The painting on the left of the Church represents the Madonna of the Rosary of Pompeii, to which the Provana were particularly devoted, as the patroness and invoked by the Christian militias at the Battle of Lepanto, where Andrea Provana (of Leyni) led the Piedmontese fleet.

It can be reached through the courtyard from the main entrance. It is obtained inside the oldest wall of the Castle, but built in neoclassical style, characteristic of the new part. In fact, the current chapel, a semi-public oratory, dates back to the early 1800s and takes up the tradition of the previous chapel dedicated to the Assumption, of which the Popes have renewed ancient privileges.