The Basilica of S. Maria in Trastevere, is supposedly the first official place of Christian worship built in Rome and certainly the first dedicated to the cult of the Virgin. According to the legend, the church was built in 340 on the oratory founded by Pope Callixtus I in the 3rd century, when Christianity had not yet spread.
Sant'Agata in Trastevere was built in 1710-11 on an ancient medieval church first mentioned in 1121 in a bull of Pope Calixtus II. In 1575, Pope Gregory XIII granted the church to the Archconfraternity of Christian Doctrine (Agatisti), which later joined the Congregation of Doctrinarians in the 18th century. In 1710-1711, under the pontificate of Clement XI, the church was completely rebuilt by Giacomo Recalcati.
The church of San Salvatore in Onda was first mentioned in a bull of Pope Honorius II in 1127. In 1445, the church and the adjoining convent were granted by Pope Eugene IV to the Friars Minor Conventual, while on 14 August 1844, Gregory XVI granted it to Vincenzo Pallotti for the religious community he had founded. After this transfer of ownership, the church, which had already undergone a radical restoration in the 18th century with the raising of the floor, was once again rebuilt by the architect Luca Carimini, who highlighted the columns and capitals of the original structure.