This church is attributed to the Carmelite Costaguta who probably built it in 1634. The facade, with its distinctive ducal coats of arms, was only finished in 1673 by Solaro. Inside a splendid altar by Castellamonte has been preserved while the statues on the pulpit are the work of Carlone. The life of the saint is narrated by two frescoes by Dauphin. On the left, the first chapel was designed by Juvarra while in the second, under the altar steps, the heart of the prince cardinal Maurizio of Savoy and the internal organs of his wife-niece Ludoovica are buried. On the right, the second chapel has a painting by Legnanino.