The old guidebooks to the tombs of the Roman martyrs make mention, in connection with the catacomb of Sts. Peter and Marcellinus on the Via Labicana, of the Four Crowned Martyrs (Quatuor Coronati), at whose grave the pilgrims were wont to worship (De Rossi, Roma sotterranea, I, 178-79). One of these itineraries, the "Epitome libri de locis sanctorum martyrum", adds the names of the four martyrs (in reality five): "IV Coronati, id est Claudius, Nicostratus, Simpronianus, Castorius, Simplicitus". These are the names of five martyrs, sculptors in the quarries of Pannonia (now a part of Austria-Hungary, south-west of the Danube), who gave up their lives for their Faith in the reign of Diocletian. The Acts 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. The foregoing account of the martyrdom of the five sculptors of Pannonia is substantially authentic; but later on a legend sprang up at Rome concerning the Quatuor Coronati, according to which four Christian soldiers (cornicularii) suffered martyrdom at Rome during the reign of Diocletian, two years after the death of the five sculptors. Their offence consisted in refusing to offer sacrifice to the image of Æsculapius. The bodies of the martyrs were interred at St. Sebastian and Pope Melchiades at the third milestone on the Via Labicana, in a sandpit where rested the remains of others who had perished for the Faith. Since the names of the four martyred soldiers could not be authentically established, Pope Melchiades commanded that, the date of their death (8 November) being the same as that of the Pannonian sculptors, their anniversary should be celebrated on that day, under the names of Sts. Claudius, Nicostratus, Symphorianus, Castor, and Simplicius.