The plan of the church is octagonal. The only original façade is the one looking out onto Corso Vittorio Emmanuele, while the side exterior was incorporated into the overall style in 1950. It should be recalled that a model of the church, which also features in a painting by Domenico Fetti, is today kept at the Ducal Palace. With this model, the architect provides Margherita Gonzaga a to-scale copy of his creation. After being widowed, Margherita decided to set up the adjoining monastery, where she later took up permanent residence.