Until the “Peace of the Church”* there was no a “defined Christian architecture” that specified particular artistic types with their appropriate functionality for the liturgical worship. All Pre-Constantinian Churches from the III century can be summarized in the famous Roman tituli which were called in different ways: loca ecclesiastica, Domus ecclesiae or Domus dei. These loca ecclesiastica were owned by the community and were usually located in private buildings as a donation of their owners to the community. Most of the tituli in Rome were true Roman houses found beneath the excavations of the ancient churches that were later constructed over them.
The underground state of the Church lasted until the third century when this situation changed radically thanks to Constantine’s edict of 313 and with the subsequent protectionism to church practiced by the Emperor and his family, particularly by his mother St. Helena. Constantine developed a policy that ultimately led the Church to establish a theocratic monarchy. Constantine, his successors and most of the bishops of this “new Church” protected the Christian worship and promoted the construction of large religious buildings. In those constructions, particularly promoted by Constantine’s family and located mainly in Rome, the “basilica” structure made his first appearance, as well as did a type of commemorative temple with central plan called martyria, whose name derived from the mound raised on Golgotha in Jerusalem on the tomb of Christ – the quintessential “martyrium“; this type of building had a long prevalence in early Christian architecture and was also widely distributed throughout the Christian Mediterranean and was even used in medieval Churches.
The genesis of Christian architecture took place thanks to the imperial impulse during the first half of the fourth century and particularly in Rome, Palestine (Jerusalem and Bethlehem), Constantinople, Trier and Aquileia. The main characteristics and features of Christian architecture appeared in the second half of the fourth century, when in Rome basilicas such as the churches of St. Peter and Paul were frequently and repeatedly built until their structure and form became a standard. During the second half of the fourth century the city of Milan also promoted the development of Christian architecture. The official art from Milan developed new and important architectural creations that were widely distributed and imitated in northern Italy, Provence and northern Hispania.
The Christian temple was called “basilica” in the Hellenistic way with reference to God as basileus (king in Greek). The problem of where and how the “basilica type” was originated has been the subject of varied studies and controversies. The most accepted version is that it probably had multiple origins. The initial main objective was to build a functional environment for the Christian worship and this could be achieved by using the building types offered by private and public Roman architecture. But in addition, this “building” had to reflect in its physical and spatial disposition a spiritual meaning, not in vain was considered the House of God. With these two ideas in mind, it is believed that the initial architectural models had to involve the private house (or tituli), large public buildings such as Roman baths and legal basilicas, other previous religious buildings such as mithraeums or synagogues, or even may have involved a palatial origin as in the case of the Church of St. John Lateran in Rome and the double basilica of Trier.
The type of Roman basilica created throughout the fourth century included structures with three naves*, an apse and gable roof, but did not use the vaults of Roman monumental architecture. The naves were separated by columns and arches, as in the peristyle of the ancient imperial palaces of Split or Leptis Magna from which it is believed the basic structure of a Basilica’s nave derived. There were also larger basilicas with five naves best exemplified by those of St. Peter’s and St. John Lateran, both from Constantinian times, and St. Paul Outside the Walls. A new element also important was the transept5 whose oldest examples are found in Rome and Milan as in the churches of St. Thecla in Milan and St. John Lateran, as well as in St. Peter’s Basilica, St. Paul Outside the Walls and St. Peter in vincoli. The transept makes more visible and accessible the altar, thus providing a better functionality for the basilica to the visiting pilgrims.
In Rome in times of Constantine several Christian churches were built: the first and oldest is St. John Lateran ca. 312-319 A.D. which has a famous circular baptistery, St. Peter’s Basilica at the Vatican built between 324 and 330 A.D., the Basilica of the Holy Cross, the Basilica of St. Peter and Marcellinus including the octagonal mausoleum of St. Helena, the Basilica of St. Agnes with its famous circular mausoleum today known as the Church of St. Costanza. Such a similar trend in construction of basilicas took place throughout the whole Empire, including Palestine and Constantinople after its founding in 326 A.D.
The most distinctive and unique of the western churches built in times of Constantine is the old St. Peter’s Basilica at the Vatican built to house the body of St. Peter martyr. This basilica became the paradigm of church construction until well into the medieval world. Its construction probably took place between 324 and 330, though was later completed by stages, for example the façade was not completed until 360 and the great court until 390. St. Peter at the Vatican was a basilica with 5 naves and a transept . This first St. Peter’s Basilica was destroyed in 1450 to build the current Vatican Basilica, though keeping the same floor plan of 5 naves and transept. However, it was in the buildings of the Holy Land that the church type with a central plan was created, which later had a big influence in the religious constructions of the Christian Europe.
In the second half of the fourth century, Milan inherited a leading role in Christian architecture under the patronage of Constantine. But was a bishop, St. Ambrose, who turned this Imperial city in the spiritual center of the West. From this time are the Church of the Redeemer (or St. Dionysius), the Church of the Virgins (today St. Simpliciano), that of the Apostles (now St. Nazaro, ca. 382 A.D.), and the church of the St. Martyrs (or first St. Ambrose, ca. 386 A.D.), besides several baptisteries and mausoleums all in Milan.
Finally, during the sixth and seventh centuries the Roman Early Christian architecture received a strong oriental influence.
When the court moved to Ravenna and this city became the center of the Empire in 405, both architecture and particularly the extensive mosaic decoration experienced a whole new fresh impetus during the Early Christian period.
*Apse: A semi-circular or polygonal ending of the main building of a church where the main altar is usually located.
*Gable roof: A roof with two sloping sides that come together at a ridge, creating end walls with a triangular extension, called a gable, at the top.
*Nave: The central part or main body of a church building, intended to accommodate most of the congregation. It provides the central approach to the main altar and is usually divided by pillars or columns.
*”Peace of the Church”: Refers to the condition of the Christian Church after the publication of the Edict of Milan in 313 by the two Augusti, Western Roman Emperor Constantine I and his eastern counterpart Licinius, this was an edict of toleration by which the Christians were granted liberty to practice their religion without state interference.
*Transept: In a church an area set perpendicular to the direction of the nave in a “cross- shaped” form. The transept of a church usually separates the nave from the main altar.