Of ancient foundation, the fortified church of Santi Quattro Coronati is dedicated to the four crowned saints who were martyred during the reign of the emperor Diocletian (r. 284-305).
Their identities have exercised scholars for centuries, but the revised Roman Martyrology (2001) comes to this conclusion in its entry for them on November 8th (their feast day): "The commemoration of SS Simpronian, Claudius, Nicostratus, Castorius and Simplicius, martyrs who, by tradition, were sculptors in marble at Sirmium in Pannonia. When they refused to carve a statue of the god Aesculapius, because of the name of our Lord Jesus Christ, the emperor Diocletian ordered them to be thrown into the river and so, by the grace of God, they were crowned with martyrdom. Their veneration has flourished in Rome since ancient times under the title of the Four Crowned Ones in a basilica on the Caelian Hill".
The present church was built during the reign of Pope Paschal II (r. 1099-1118).
Apse
The interior has a matroneum and a Cosmati pavement, both dating back to the time of Pope Paschal II.
The fine wooden ceiling dates was installed in the 16th century.
The Glory of Heaven by Giovanni da San Giovanni
The frescoes in the apse are the work of the Tuscan painter Giovanni da San Giovanni (1592-1636).
Cloister
The left aisle provides access to a 13th century cloister, one of the most secluded spots in Rome.
The cloister leads to the Cappella di Santa Barbara. Sadly the frescoes, which once covered all of the walls, have badly deteriorated. Traces of original 9th century work survive over the south apse; the rest is 14th century. The vault depicts the symbols of the four Evangelists, the apse contains a Madonna and Child with saints, and the northern wall has a fragment of a bishop. The other panels show scenes from the legend of St Barbara.
Oratory of St Silvester
Outside the church, an entrance to the right of one of the courtyards leads to the 13th century Oratorio di San Silvestro, which is decorated with a cycle of frescoes that were painted (artist unknown) circa 1246. The central part of the floor is high-quality Cosmatesque work.
The Donation of Constantine
The frescoes depict scenes (which have no basis in fact) of the relationship between Pope Sylvester I (r. 314-334) and Emperor Constantine I (r. 306-337), including the fictional baptism of the emperor by the pope and one of the earliest depictions of TheDonation of Constantine, which was based on a forged medieval document. The frescoes were painted in the context of the confrontation between Pope Innocent IV (r. 1243-54) and the newly excommunicated Holy Roman Emperor Frederick II (r. 1220-50), and were intended to illustrate the alleged sovereignty of the Church over the Empire. The fresco of The Donation of Constantine depicts the emperor bestowing temporal authority on Sylvester I.
Entrance Wall
The cycle starts on the entrance wall with a depiction of the Deesis, featuring Christ in majesty with the Virgin Mary, St John the Baptist and the Apostles. The fresco below depicts The Emperor Dreams of St Peter and St Paul Advising Him to Contact Pope St Sylvester I in Exile.
The sanctuary preserves its 16th century frescoes by Raffaellino da Reggio (1550-78). The altar, however, is late Baroque; 1728 as the inscription informs.