Byzantine architecture is essentially a suspended architecture. Its vaults seem to be supported from above, without having any dead weight of their own. The columns are not seen as supporting elements, but as hanging roots or descending arms. The architectural conception of a building as something striving downwards is entirely consistent with the hierarchical way of thinking. There is no façade; all richness is concentrated in the spiritual core of the building. Most churches are cube-shaped on the outside, with a central dome or several domes, with the central one towering over the outer ones. The churches are plain. It is only in the Palaiological period (the late Byzantine era) that some variety is brought to the façade.
The periodization corresponds to the basic scheme of Byzantine art, which was measured in particular by the periods of greatest building activity and is significantly correlated with the economic conditions of the empire. As independent periods, the periods 375-600, 775-950, 1025-1200, and 1250-1400 can be connected with the dynastic situation. This confirms, also by statistical methods, the classical division of Early Byzantine architecture and the ages of the Macedonians, Comnenes, and Palaiologians and their overlaps especially between the architecture of the Macedonians and Comnenes, as well as the Comnenes and Palaiologians.
The early Byzantine architecture
Early Christian architecture forms an origin of Byzantine architecture. After the legalization of Christianity in 313 (by the Edict of Tolerance of Milan) and the change to the new capital Constantinople, the demand for representative buildings for the new religion increased by leaps and bounds, whereby pagan building types were adopted (basilica, central building).
The basilica, in ancient times a meeting room or market hall, became the main type of sacred architecture.
With the basilica as a sacred building in the early Middle Ages, the multi-aisle design and the illumination through the clerestory (high nave wall above the columns) were adopted. In the early period, the basilica was often unroofed, i.e. open to the roof truss at the top. The apse was usually located in the east. In it stood the bishop's throne, there were benches for the clergy, often also an altar and a lectern. As in the western early Christian basilicas, the narthex and an atrium were located in the west.
Characteristics of the central building were the centralized, mostly point-symmetrical, more rarely axially symmetrical ground plan, mostly covered with a dome.
From the (Roman, ancient) central building, the (Byzantine) central building with a cross ground plan developed through the expansion by means of side aisles. In the combination, the dome basilica and the cross-domed church emerged in the 5th century.
Important examples of these buildings can be found in Ravenna (San Vitale, Sant'Apollinare Nuovo, Sant'Apollinare in Classe) as well as in Istanbul (the former Constantinople) and other places.
The Middle Byzantine architecture
The end of iconoclasm in 843 and the establishment of the Macedonian dynasty in 867 by Basileios I (867-886), an illiterate soldier who became a successful general and eventually ascended the Byzantine throne, marked the beginning of a rebirth of the Byzantine Empire.
The architecture of the Macedonians begins with the construction of the now destroyed Nea Ekklesia (Greek: Νέα Ἐκκλησία = "New Church" after conversion into a monastery later: "Nea Moni") under Basileios I. 876-880 as a new Hagia Sophia in the southeastern part of the Great Palace. The ground plan of the five-domed church of the Nea Ekklesia as a four-column building, the barrel cross supporting the dome is supported by four columns or pillars. This became stylistically influential for all Byzantine cross-domed churches of the time and spread to the Balkans and Russia. The Nea Ekklesia occupied a special position in the Byzantine court ceremonial until the 11th century. The valuable relics from the three crosses of the crucifixion of Jesus were brought from the treasury of the palace to the Nea and celebrated by the court and the emperor in an elaborate ceremony lasting several days. The Nea also acquired a special significance in this period due to the number of relics. Among other things, the relics of the sheep's coat of the Prophet Elijah, the table of Abraham, at which he is said to have conversed with three angels, the horn of Samuel, with which he is said to have anointed David, and the relics of Constantinethe Great were kept here. Pilgrims of the 12th century also reported that the staff of Moses and the cross of Constantine were displayed in the Nea. The oldest surviving example of Middle Byzantine sacred architecture in Constantinople is the Church of Constantine Lips, dedicated to the Virgin Mary. In almost all of these churches, the five-domed nave is supplemented by flank rooms.
While the most important monuments of early Byzantine art had been public buildings, the important monuments of this period were of a private character, that is, they were reserved for the dignitaries and court officials who had access to the palace. The social base of "imperial" art had been diminished. When the majority of ecclesiastical buildings became private, they gave way to monastic churches.
The monastery churches
Byzantine monastic churches are almost always cross-domed churches. They form with their corner rooms a square in which a Greek cross is inscribed. Mostly they are of modest dimensions. This was partly because the technical difficulties increase with size, and partly because the churches were usually built for numerically small orders. The dome rests on four arches, which are extended in the direction of the cross by four barrel vaults of equal length. The approximately square spaces between the arms fill the corners. The roofs of the spaces are kept lower so that the cross can be seen from outside. Four additional, smaller domes may step over the corner spaces between the arms of the cross or over the arms of the cross themselves, making a total of 5 domes crowning the church. The four-column type can be considered a sub-type of the cross-domed church: In the four-column church, the dome is supported by columns rather than pillars. That is why the church is usually smaller, higher and does not contain galleries. This eliminates the separation between the corner rooms and the main room. Another subtype is the ambulatory church. Here, the arms of the cross and the corner rooms form a gallery, which is often separated from the main room by triple arcades.
The late Byzantine architecture ("Palaiological Renaissance")
The architectural styles of the previous eras have been preserved: Cross-domed, four-post, and ambulatory churches. The dimensions became more modest and the exterior received novel, colourful accents through different layers of brick and house stone. The cross-domed church remained popular. One of the innovations was that churches were provided with a gallery on three sides. Churches were also rebuilt and decorations became more varied. The buildings became more irregular and the domes became larger.
The Palaiological Renaissance remains significant above all because of the internationalization of Byzantine art. It is no longer limited to the narrower area of the Byzantine Empire and its artistic centers in Constantinople, Thessaloniki and Mount Athos. By being passed on to the Slavic countries and the fact that these were often economically and politically more vital than the remnants of the late Byzantine Empire, Byzantine art also opened up to new impulses. The art of building, especially in Russia and Serbia, does indeed fall back on Byzantine models, but especially after 1375 it develops tendencies that noticeably bear a new signature in architecture and painting. In addition to the churches of the Morava School, the innovations in fresco painting of the Palaiological Renaissance are also characterized by more individuality, tending towards a stronger humanism and reinterpreting the often schematic specifications.
