Severus (or Secundius), Severian(us), Carpophorus, and Victorinus were martyred at Rome or Castra Albana, according to Christian tradition.
According to the Passion of St. Sebastian, the four saints were soldiers (specifically cornicularii, or clerks, in charge of all the regiment's records and paperwork) who refused to sacrifice to Aesculapius, and therefore were killed by order of Emperor Diocletian (284-305), two years after the death of the five sculptors, mentioned below. The bodies of the martyrs were buried in the cemetery of Santi Marcellino e Pietro on the fourth mile of the via Labicana by Pope Miltiades and St. Sebastian (whose skull is preserved in the church).
The second group, according to Christian tradition, were sculptors from Sirmium who were killed in Pannonia. They refused to fashion a pagan statue for the Emperor Diocletian or to offer sacrifice to the Roman gods. The Emperor ordered them to be placed alive in lead coffins and thrown into the sea in about 287. Simplicius was killed with them. According to the Catholic Encyclopedia,
of these martyrs, written by a revenue officer named Porphyrius probably in the fourth century, relates of the five sculptors that, although they raised no objections to executing such profane images as Victoria, Cupid, and the Chariot of the Sun, they refused to make a statue of Æsculapius for a heathen temple. For this they were condemned to death as Christians. They were put into leaden caskets and drowned in the River Save. This happened towards the end of 305."
When the names of the first group were learned, it was decreed that they should be commemorated with the second group. The bodies of the first group were interred by St. Sebastian and Pope Melchiades (Miltiades) at the fourth milestone on the Via Labicana, in a sandpit where there rested the remains of other executed Christians.
It is unclear where the names of the second group actually come from. The tradition states that Melchiades asked that the saints be commemorated as Claudius, Nicostratus, Simpronian, and Castorius. These same names actually are identical to names shared by converts of Polycarp the priest, in the legend of St. Sebastian. According to the Catholic Encyclopedia, however, "this report has no historic foundation. It is merely a tentative explanation of the name Quatuor Coronati, a name given to a group of really authenticated martyrs who were buried and venerated in the catatomb of Saint Marcellinus and Pietro, the real origin of which, however, is not known. They were classed with the five martyrs of Pannonia in a purely external relationship."
The bodies of the martyrs are kept in four ancient sarcophagi in the crypt of Santi Marcellino e Pietro. According to a lapid dated 1123, the head of one of the four martyrs is buried in Santa Maria in Cosmedin.
The rather confusing story of the four crowned martyrs was well known in Renaissance Florence, principally as told in the thirteenth-century Golden Legend by Jacopo da Voragine. It appears that the original four martyrs were beaten to death by order of the emperor Diocletian (r. AD 284-305). Their story became conflated with that of a group of five stonecarvers, also martyred by Diocletian, in this case because they refused to carve an image of a pagan idol. Due to their profession as sculptors, the five early Christian martyrs were an obvious choice for the guild of stonemasons, but their number seems often to have been understood to be four, as in this case.
Problems arise with determining the historicity of these martyrs because one group contains five names instead of four. Alban Butler believed that the four names of group one, which the Roman Martyrology and the Breviary say were revealed as those of the Four Crowned Martyrs, were borrowed from the martyrology of the Diocese of Albano Laziale, which kept their feast on August 8, not November 8. These four "borrowed" martyrs were not buried in Rome, but in the catacomb of Albano; their feast was celebrated on August 7 or August 8, the date under which is cited in the Roman Calendar of Feasts of 354. The Catholic Encyclopedia wrote that the "martyrs of Albano have no connection with the Roman martyrs".
The double tradition may have arisen because a second passio had to be written. It was written to account for the fact that there were five saints in group two rather than four. Thus, the story concerning group one was simply invented, and the story describes the death of four martyrs, who were soldiers from Rome rather than Pannonian stonemasons. The Bollandist Hippolyte Delehaye calls this invented tradition "l'opprobre de l'hagiographie" (the disgrace of hagiography).
Delehaye, after extensive research, determined that there was actually only one group of martyrs – the stonemasons of group two - whose relics were taken to Rome. One scholar has written that “the latest research tends to agree” with Delehaye's conclusion.
The Roman Martyrology gives the stonemasons Simpronianus, Claudius, Nicostratus, Castorius and Simplicius as the martyrs celebrated on November 8, and the Albano martyrs Secundus, Carpophorus, Victorinus and Severianus as celebrated on August 8.
In the fourth and fifth centuries a basilica was erected and dedicated in honor of these martyrs on the Caelian Hill, probably in the general area where tradition located their execution. This became one of the titular churches of Rome, and was restored several times.
The Four Crowned Martyrs were venerated early in England, with Bede noting that there was a church dedicated to them in Canterbury. This veneration can perhaps be accounted by the fact that Augustine of Canterbury came from a monastery near the basilica of Santi Quattro Coronati in Rome or because their relics were sent from Rome to England in 601. Their connection with stonemasonry in turn connected them to the Freemasons. One of the scholarly journals of the English Freemasons is called Ars Quatuor Coronatorum, and the Stonemasons of Germany adopted them as patron saints of "Operative Masonry."
Around 1385, they were depicted by Niccolò di Pietro Gerini. Then in about 1415, Nanni di Banco fashioned a sculpture grouping the martyrs after he was commissioned by the Maestri di Pietra e Legname, the guild of stone and woodworkers, of which he was a member. These saints were the guild's patron saints. The work can be found in the Orsanmichele, in Florence. Finally, they were also depicted by Filippo Abbiati.