When the Emperor Constantine issued the carefully worded Edict of Milan in 313 legalizing Christianity, 4 months after defeating his rival Maxentius at the Battle of the Milvian Bridge under the sign of the Christian cross, Christianity changed profoundly. It changed from a disparate underground spiritual movement into a religion. Just 11 years before, Christianity faced its last and worst persecution, an empire wide campaign by the Emperor Diocletian to wipe it out utterly. He saw Christianity as a mortal threat to his effort to hold the Empire together in a religious cult of the Divine Emperor. Thousands died in that campaign. Now, this battered remnant of an underground movement woke up one morning to find itself the Establishment. Constantine not only legalized Christianity, but gave it imperial sponsorship. Public money and government power and policy would be used to propagate and support the new religion.
On the one hand, this must have seemed to be a miraculous salvation to Christians at the time. On the other hand, it created enormous and unanticipated problems for the early Church. The state patronage and support came with a very high price. The fortunes of the Church became bound up with the fortunes of the Roman Imperial state. There was enormous pressure on the Church by the State to speak with one mind and voice in matters of belief. Constantine was determined to make Christianity into an ideological force for holding the Empire together. He needed its universal and exclusive claims for the State. What Constantine got was a mischegoss of quarreling congregations and widely disparate claims and beliefs. There was no central authority that everyone could agree on, and at this time, there was no Bible in any form that we would recognize.
Thousands of people began pouring into a Christian community that was unprepared to accommodate them. The intimate and largely informal rituals of the house church, where probably no more than 30 gathered at a time, were no longer practical for gatherings of hundreds and thousands of people. There was very little in the way of church governance prepared to meet the needs of so many people.
Constantine's first big project was to begin the rationalization of Christian belief into "orthodoxy." He convened the first great Council at Nicea to begin this process. The new Christian religion was to be codified into a series of credal and doctrinal statements that had the consensus of church leaders and the imprimatur of the State. Christian texts were likewise to be organized into a Scriptural canon. The Church as an institution was to be organized into a hierarchy of teachers, presbyters, and pastors.
Architecture was an instrument of state policy in Rome. The Romans used architecture to organize and direct vast masses of people in a huge state that spanned 3 continents. The Roman military was not only a highly efficient fighting force, it was a highly efficient construction force. Most public building was done under the direction of the military. They built the enormous empire-wide road system, water supply and drainage systems, public buildings, monuments, temples, even entire cities were built to order quickly and efficiently. This was true since the days of the Roman Republic, and now this force was at the disposal of the Christian religion. Constantine and his successors used art and architecture to spread the Christian religion, and to identify it ever more closely with the Imperial establishment.
Constantine built a number of great churches in Rome and in Palestine beginning with the Lateran Church, the first ecclesia cathedralis, the first cathedral, for the Bishop of Rome. Most of these great churches were built beyond the Roman city center so as not to offend the conservative sensibilities of the Roman Senate. The even larger Saint Peter's was built on a slope of the Vatican hill outside the city walls over the grave of Peter, the first such great church to be built directly over a saint's tomb instead of next to it. Leveling and stabilizing the slope to accommodate the great church was a major engineering feat. Constantine built the great churches of the Nativity at Bethlehem and the Holy Sepulcher in Jerusalem over the traditional locations of the central events in Christ's life.
Nothing of those original churches by Constantine remains. St. Peter's and the Lateran church were completely rebuilt in the 16th and 17th centuries. The churches in Palestine were destroyed and rebuilt several times over down to the 20th century.
There is only one church from Constantine's reign that survives relatively intact. That is the Church of Santa Costanza, the mausoleum he built for his sainted daughter near the entrance of the now ruined Church of St. Agnes.
The building is a round martyrium church originally containing Costanza's tomb in the center. It was built for a once common ritual in the Mediterranean world, circumambulation, walking around a holy site. Once, every religion did this. Now, only the Muslims do this as far as I know.
The building, like most early Christian architecture, is built around its interior, turning plain brick walls to the rest of the world. The columns are recycled from earlier structures. Pillaging earlier building parts was already commonplace before Constantine became emperor. The practice saved time and money, and added the luster of the glorious classical past to the crisis-ridden and uncertain present.
This is the ambulatory of Santa Costanza built for those circumambulating crowds come to pray at the imperial daughter's tomb. The ceiling mosaics above are original to Constantine's time, and they present a little problem.
The mosaic decoration is very charming and beautiful in places, but it is not very obviously Christian. It looks like the floor decoration of an expensive Roman house moved to the ceiling. Christian imagery is still unformed at this time. The artists who made these mosaics probably were not Christian. And there is still a very syncretic aspect to these pictures. The grape harvest once associated with Bacchus is now in a Christian context and can be associated with any number of vineyard and wine metaphors in Christian Scripture. It is not likely that the artists were aware of those associations.
As mentioned earlier, a consequence of the legalization of Christianity was a huge population of new Christians. The old house church rituals were obsolete, but even those throngs wanted something of their old participatory nature even if the intimacy was no longer available. A new type of building had to be created to meet this need.
The old Roman temple was not available. It was too closely associated with the old religion, and was impractical anyway for public ceremonies. There was a type of secular building that was built for large gatherings of people, the basilica. The basilica is where the Emperor and city and provincial officials held public audience. It's where law courts met and balloting took place for certain public offices.
These are the ruins of what was once the largest and finest of all Roman basilicas, the Basilica Ulpia built by the Emperor Trajan for his forum and designed by the great Syrian architect Apollodorus of Damascus. As you can see, there is very little left of it.
Here is the latest in a series of conjectural reconstructions of this once great building based on what remains and on literary descriptions. The Basilica Ulpia, like most Roman basilicas, was a long hall topped with a flat wooden roof. It was a large interior for large public gatherings. In the days before electric lighting, people had to be able to see. That problem was solved by a row of openings or windows just under the ceiling called the clerestory. These lit the interior with the light of the sun so that His Divine Majesty could read his speech and the lawyers, clerks, and magistrates could read their briefs.
The Constantinian Church took this building type and transformed it for religious purposes. The first thing the Christians did was to give this design a focus, a center point. That focus was the altar where the sacraments took place. Christians redesigned the basilica to focus people's attention and allow them to see and to participate in the Eucharist taking place. The altar dominated the end of a long hall perfectly suited for the processional liturgies of the Latin Church. The new basilican church was very hierarchical; clergy occupied the apse around the altar and a tribune usually separated by a balustrade. The baptized communicants thronged the long hall of the nave to watch and to participate in the Mass. Catechumens and postulants occupied the narthex, and an exterior courtyard that was a feature of some early churches. The church was designed around proximity and approach to the altar.
None of the basilican churches from Constantine's time survive, but there are a number of later ones from about the time of the reigns of the Emperors Theodosius and Honorius that do survive in Rome. One of them is pictured above, Santa Sabina. It's a relatively small church built by Bishop Peter the Illyrian for pilgrims and residents in Rome from the Balkans. It has all the features of the old Roman basilica with the new focus upon the altar in the apse.
The columns in the nave of Santa Sabina are, once again, recycled from earlier buildings. After Christianity was made the state religion in the reign of Theodosius, and church attendance became mandatory, the old temples were closed and began their long careers as quarries of readily available building material. You can see here the clerestory and wooden roof that are holdovers from the pre-Christian secular building type.
There is one church in Rome where we can get some sense of the grandeur and splendor of the old Constantinian basilican churches. The Church of Santa Maria Maggiore is the first major church dedicated to the Virgin Mary and was built following the Council of Ephesus clarifying her role in the Incarnation as "God Bearer" and "Mother of God." The church has been modified and augmented a lot in its history, but much of its original magnificence survives. It is the only one to retain its original 5th century mosaic decoration.
It is a huge church that gives us some idea of the lost splendor of the original St. Peter's and the Lateran Church. The altar is built over a shrine that holds a relic that was claimed to be the manger of Christ's birth.
At this time, there were no set rules on the mosaic decoration of these churches. Like the old synagogue at Dura Europos, the purpose of these images was to teach, to aid in the instruction of the faithful through Scriptural readings and sermons. The arch over the apse faced into the congregation, and became referred to as a "triumphal arch" recalling the victory monuments of pre-Christian Rome. Usually the subject matter on these, and around main portals into the church, was apocalyptic, the triumphant Second Coming in glory. In the Latin church, apocalyptic subject matter became associated with doors and arches perhaps influenced by this passage from Revelations, "After this I looked, and there before my eyes was a door opened in heaven; and the voice I had first heard speaking to me like a trumpet said,'Come up here and I will show you what must happen hereafter.'"
The triumphal arch in Santa Maria Maggiore is an exception. It shows not the Second Coming of Christ, but His First Coming, as would be appropriate for a church dedicated to the Virgin Mary.
The Virgin Mary in these mosaics is definitely not the working class teenage mother of the Gospel accounts, but appears garbed and crowned like an empress with angels serving as retainers and servants. The top register in this picture shows the visit of the Magi. Christ sits enthroned like a little emperor on a huge jeweled throne. The Virgin Mary is not the woman in the dark shawl to Christ's left, but the crowned empress on her own throne to Christ's right. Poor Joseph must stand behind one of the visiting Magi to the far left. The angels stand behind Christ like officials at a public audience for the reception of foreign princes. This is a none-too-subtle attempt to conflate Divine and secular authority, to incorporate Church teaching into state ideology.
The squares just above the colonnade contain the original mosaics from the nave of the church, the only ones to survive in a late Roman basilican church. The nave mosaic cycles are the creation of the historical and narrative nature of Latin Christianity. The mosaic panels in the nave that we pass as we walk toward the altar tell stories. Latin Christian thought always placed Christian teachings within the context of history; both larger history and individual history. We experience history as a kind of procession through time. The processional liturgies of the Latin Church were meant to be an image of the Church moving forward through time toward fulfillment in the Second Coming. The nave and its decorations were built around that processional concept of history. Again, there were no definite rules about what stories should be in the nave. According to accounts of cycles in other basilican churches, they were each unique. The cycles in St. Peter's told the story of Moses on one side and of Christ on the other side of the nave. The stories in the nave mosaics of Santa Maria Maggiore are all from the Old Testament, again as would be appropriate for the Virgin Mary, the last manifestation of Israel before the New Covenant and the living link with the Old Covenant.
This mosaic panel from Santa Maria Maggiore shows Abraham entertaining the Three Strangers who turn out to be angels. This is the earliest of all surviving depictions of this subject. It is a vivid piece of storytelling in bright colors with lots of figures. Abraham and the Three appear twice in the same scene. We see Sarah laying out refreshments and caught laughing at the idea that she could still bear children at her great age. This is also one of the earliest uses in art of the Christian practice of treating Old Testament stories as prophetic prototypes for the New Covenant. The Three Angels were meant to be seen as a prophetic manifestation of the Trinity. The artist makes this clear in the upper group where the three are joined together in the first mandorla to appear in Christian art.
These brightly colored storytelling pictures resemble very closely the swarming figures on the Column of Trajan that tell the story of Trajan's conquest of Dacia, and the illustrations from the very few surviving books from late Imperial Rome.
The apse mosaic was the largest and most prominent mosaic of all in the church. Right over the altar, it presented a glorious image of the Heavenly Court, a theophany, a splendid and miraculous vision of the Divine. This was appropriate to the altar where Christ was believed to be made present in the Eucharistic mystery.
The original apse mosaic of Santa Maria Maggiore was replaced in the 13th century with Jacopo Torriti's splendid masterpiece of Italo-Byzantine art showing the very un-Byzantine subject of the Coronation of the Virgin Mary in Heaven at the right hand of Christ.
We've already seen the earliest surviving of these apse mosaics from the church of Santa Pudenziana in Rome.
Here is the 6th century apse mosaic of Saints Cosmas and Damian in Rome. Christ is shown in a dual role as Great Teacher and coming down from the sky in the Second Coming. On the left is St. Paul with the martyred Saint Cosmas. On the far left is Pope Felix IV. On the right is St. Peter with Saint Damian and another martyr saint, Theodorus Tiro. The row of sheep on the frieze below refer to the "flock" of believers in the care of the Church and the saints. The almost symetrical composition, the bright flat colors, look forward to Byzantine art to come soon after this mosaic is completed.
The basilican church invented during the reign of the Emperor Constantine is still the basic format used by a lot of churches down to the present day. Above is a Roman Catholic Mass in a new church still using a basilican format with apse and nave. As can be seen here, it is designed around and for the processional liturgies of the Western Latin tradition.