Chiesa di San Callisto

Of ancient origins, according to tradition it is built on the house where Pope Callistus I (217-222) used to retire to pray and where he suffered martyrdom by drowning: in the courtyard of the former convent, attached to the church, is the well where the pontiff is said to have been martyred. The well is preserved in the church consecrated to the saint, while the stone that was tied around his neck in the nearby Basilica Maggiore of S. Maria in Trastevere remains with other instruments of torture.A memorial oratory was initially built on the site of the martyrdom and then, in the 8th century, Pope Gregory III had a temple erected there. Rebuilt in the 12th century, the church was rebuilt again in 1610 to a design by Orazio Torriani, when the adjoining monastery was also erected to house Benedictine monks. Since 1517, the church has been the seat of the cardinal's title of the same name. Due to the French occupation at the beginning of the 19th century, both buildings suffered serious damage that necessitated substantial restoration work carried out during the pontificate of Pius IX in 1851. The ensemble underwent major new restoration in the 1930s, conducted by architect Giuseppe Momo.
The façade of the church dates back to the 17th century and shows the coat of arms of Paul V in the upper order. The interior has a single nave with a chapel on each side and preserves, in particular

- in the right chapel, two angels attributed to Gian Lorenzo Bernini,
- they support Pier Leone Ghezzi's painting St Maurus Abbot;
- in the vault, the Glory of St Callistus frescoed by Antonio Achilli;
- in the left chapel, the well where, according to tradition, Pope Calixtus I suffered martyrdom.