The siting of the Basilica Constantiniana, or San Giovanni in Laterano (as it came to be known, in recognition of the site’s original owner), was of both symbolic and political importance, not only because it was the first great Christian church in Rome but also because it declared that the Christians had no ambition to obliterate the more ancient Roman order: coexistence was the watchword between Constantine and the old aristocratic families. San Giovanni in Laterano was and remains the cathedral of Rome (not, be it noted, Saint Peter’s, despite what so many tourists think). It is the mother church of all Christendom, and its role is stated in the inscriptions cut not once but twice on its façade: “Omnium urbis et orbis ecclesiarum mater et caput,” “The mother and head of all churches of the city and of the world.”
It set the archetypal form for Christian churches in the West by adapting, with minimal alterations, a Roman architectural form: the “basilican” plan, so called after the Greek term meaning “royal house”: a long rectangular nave, a public space with entrance and apse on the opposite short sides. Side aisles, framed out from the body of the nave, provided space for ambulatories and chapels. This had been adapted from pagan Roman models (the first basilica in Rome had been built by Marcus Porcius Cato back in republican times, in 184 B.C.E.). It served the same type of ceremonies: lines of acolytes, stately processions toward a designated focus, such as are involved in the sacraments of Holy Communion and Confession. The basilican plan lends itself to a clear and strict separation of the celebrant (the priest) from his communicants, as the centralized plan of the Greek rite does not. But the basilican Christian plan was open to a wide variety of form: it could have several naves (some had as many as nine of these aisles, separated by rows of columns). Rectangular, axial basilicas of this kind were less costly to build than the centrally planned ones, roofed with masonry domes, favored in the East, because they did not require the elaborate curved shuttering needed to construct arches and domes.
It was, by the standards of its time (or any time), an enormous building, with a four-aisled nave ninety-eight meters long and some fifty-six wide. Its main columns were of red granite, and its secondary-aisle columns were recycled from ancient buildings and were of green marble. Apart from the enormous cost of construction, Constantine donated enough sheet gold—all looted long since—to decorate the apse.
This was not Constantine’s only ecclesiastical venture in Rome, of course. He endowed what became a private chapel for the devotions of his mother, Helena (250–330), Santa Croce in Gerusalemme, within the Sessorian Palace. In about 326, the future Saint Helena made a pilgrimage to the Holy Land, from which she brought back shiploads of relics, including some tubs of soil from Calvary, and (a considerable engineering feat, if true) the stairs which Christ was believed to have climbed in the palace of Pontius Pilate in Jerusalem.
Some early Christian churches in Rome are almost bewildering palimpsests. A case in point is the Basilica of San Clemente, less than half a mile from the Colosseum. Its existence began in the first century C.E., when it was raised on the foundations of a building—perhaps a warehouse, perhaps an apartment complex—burned out in the Great Fire of 64 C.E. and owned by a consul named Titus Flavius Clemens, a great-nephew of the Emperor Vespasian. According to the Roman chroniclers Dio Cassius and Suetonius, Clemens was executed in 95 C.E. on charges of impiety connected with “godlessness” and Judaism, brought by the Emperor Domitian. Whether this indicated some connection with Christianity is a matter of debate; the pious like to believe it was. What is fairly certain, however, is that by the late second or early third century the dark, dank, cavelike space within the former insula had become a Mithraic temple, which was abandoned when, in the fourth century, Mithraism—imported to Rome largely by legions returning from Asia Minor after the campaigns of Pompey2—was outlawed by the now victorious Christians.
Frustratingly little, and from documentary sources almost nothing, is known about this religion. It was a mystery cult that had managed to keep most of its secrets. Mithras, or Mithra, was a god hero who embodied light and truth. His acolytes knew him as, among other honorifics, “lord of the wide pastures,” and his central, mythic action was the capture and killing of a wild bull, which he dragged to a cave and then slaughtered. From its blood sprang life and grain. The sacrificing god was known as Mithras Tauroctonos, Mithras the Bull Slayer. The killing of the bull was therefore a highly generative act, and it may be that its memory is preserved, in a much-mutated form, down to the present day in the Spanish cult of the bullfight. This story may descend from the Greek myth of Perseus killing the Gorgon Medusa, and may have originated with King Mithridates VI of Pontus, who was named for Mithras but claimed descent from Perseus.
Mithraism never claimed a mass collective audience such as Christianity acquired. It had no need of huge basilicas—its cavelike gathering places were usually no more than sixty by twenty-five feet. Moreover, the congregation it did have was deliberately restricted. Mithraism was a masculine warrior-cult from which women were strictly excluded. Mithraea (the term for its meeting places) have been found in Rome, about a dozen in all, the largest being the Mithraeum Thermarum Antonianarum, underneath the Baths of Caracalla. The remains of others exist in Ostia, a reminder of how common Mithraic worship was in ports, among sailors and travelers.
There were similarities between the cults of Mithras and of Jesus, but they generally turn out to be superficial, and there is little support for the once-common view that Christianity developed out of Mithraism. Certainly Mithraism was more like Christianity than any of the other Eastern mystery cults that found adepts in Rome. But the two were also very dissimilar. Christianity wanted to spread; one of its main strengths was among women, and the idea of excluding half the human race from the faith would have been incomprehensible to the early Church, whatever its suspicions of the female sex.
Above the lowest, Mithraic floor of the titulus of Clemens (or Clemente, as his name is given in Italian) is another level, dating from the late fourth century and clearly associated with Christian worship. Over the centuries, it was adorned with a series of frescoes and mosaics, of which the most beautiful is a depiction of the Tree of Life in its apse—Christ crucified, with white doves roosting on the arms of his cross, and writhing spirals issuing from the base of the tree to fill the gold semicircle of the background. Of all the early Christian monuments of Rome, this twelfth-century mosaic is one of the most decorative and satisfying.
Various legends cling to the church. One is that after Saint Clement, third successor to Saint Peter as bishop of Rome, was flung into the Black Sea in 98 C.E. by the impious Romans with an anchor tied to his neck, his body was recovered by two Slavic saints, Cyril (826–69) and Methodius (815–85), brought to Rome, and buried in the church that bears his name. Another is recorded in a fresco in the nave. It tells how a Roman husband, peeved at his wife’s constant attendance at Mass, referred to the clergy of San Clemente’s as fili dele pute, “sons of whores.” Not only is this a surprising inscription to be found anywhere in a church; it is said to be the earliest known writing in vernacular Italian.