This church, which is dedicated to St Prosper of Reggio Emilia, was built on the site of an Etrusco-Roman burial ground, stones from which are incorporated into its walls.  Part of the north wall probably dates to the Etrusco-Roman period, but the rest of the main part of the church was probably built in the 7th or 8th century, and rebuilt and extended to the left in the 11th or 12th century. 

The earliest documentation dates to 1285, when this was a parish church.  It had a chequered history:

1. ✴It appeared in a list of the possessions of the Abbazia di Pomposa near Ferrara in 1436.
   

2. ✴It had passed to the canons of San Lorenzo by the 16th century and was used as a place of burial for those who died in an outbreak of plague in 1527.
   

3. ✴In 1553, when Canon Troilo Baglioni became the parish priest, the church was in a poor state and he requested help from the Commune to restore it.
   

4. ✴In 1567, the parish was abolished and the church passed to the Collegio del Seminario.  The upper storey was probably added at about this time.
   

5. ✴In 1786, Annibale Mariotti reproved the authorities of the seminary for allowing this ancient church to be converted for secular use.
   

6. ✴In 1905, at which time the church belonged to the Opere Pie Donini, Ettore Ricci discovered the frescoes in the chapel (see below).
   

7. ✴In 1935, the Salesians of the Istituto Don Bosco bought the property and began its restoration.
   

Interior of the Church

The main part of the church is in the form of a single nave.  Its barrel-vault seems to have been part of the restoration of 1553; this space was probably originally much higher and would have had a wooden trussed ceiling.

An arch in the right wall opens onto a parallel chapel. 

Ciborium (8th century)

San Prospero (13th century) 

Frescoes in the chapel (1225)

In 1905, as noted above, Ettore Ricci discovered these frescoes in the chapel to the right.  Unusually at this early date, they were signed (by Bonamicus, the first Perugian painter for whom we have a name) and dated (1225) in an inscription above the entrance arch.  The inscription adds that they were painted in the time of Pope Honorius III, the Emperor Frederick II and the priest Rinaldo, who was then in charge of San Prospero.

The frescoes on the entrance wall depict:

1. ✴Christ and the Apostles (above the inscription); and
   

2. ✴a group of Benedictine saints and a donor (perhaps the priest Rinaldo) kneeling before St John of Perugia (to the right of the inscription).  St John of Perugia was sent to Spain by St Francis in 1216 and martyred in Valencia.  The date of his death is usually given as ca. 1230, suggesting that:
   

3. •the frescoes were executed over a period beyond the date of 1225 in the inscription;  or
   

4. •St John of Perugia actually died at an earlier date than had been previously believed.
   

The frescoes in the top register on the wall opposite the entrance depict a series of prophets. 

The frescoes below them depict:

1. ✴SS Mary Magdalene, Margaret and Brigid of Ireland, with an inscription relating to the missing St  Illuminata  (to the left);
   

2. ✴St Prosperus (illustrated here, with his congregation) and St Michael; and
   

3. ✴Abraham (to the right).  A poor man called Lazarus is among those protected in the bosom of Abraham, while the rich man who had denied him food looks on from Hell.
   

The frescoes in the bottom register of this wall depict SS Leonard and Benedict, with inscriptions relating to the missing SS Nicholas and Sylvester.

1. ✴an angel (in the top register), which was originally part of an Annunciation;
   

2. ✴SS Herculanus and John the Baptist (in the middle register); and
   

3. ✴fictive curtains below.
   

Frescoes in the Main Part of the Church (14th century)

1. ✴the damaged figures of the Annunciation (to the left); and
   

2. ✴St Antony Abbot (to the right).