the fall of Rome, and which spread thence westward into Italy and northward into what is now Russia, where it still persists in attenuated and almost grotesque form. The pictorial and decorative art associated with this architecture was widely diffused through Europe (see PAINTING), and materially affected Western art. With the final division of the Roman empire between Honorius and Arcadius (395 A.D.), Constantinople became not only the capital of the Eastern or Greek empire, but the most important city of Christendom; the chief centre for centuries of Christian art and learning, especially of Greek culture as distinguished from the Latin, and of the Eastern Church as distinguished from that of Rome. Under the great Emperor Justinian (527-65 A.D.) there ensued an extraordinary activity in the building of churches, not only in the capital but in Syria, Dalmatia and Macedonia and in Ravenna, the seat of the Byzantine Exarchate of Italy. This architecture was chiefly the work of Asiatic Greeks, who introduced into the construction of churches certain traditional Asiatic forms and methods, especially in types of vaulting in brick or stone. They abandoned the distinctive Latin type of church-the basilica, with its three aisles and wooden roof and substituted for it new types both of plan and construction, of which the dominant feature was invariably a central dome, raised above the surrounding structure and pierced by a ring of windows at its base. They revived certain features of Roman secular vaulted buildings and blended with these an Oriental taste for applied decoration in color, creating out of this combination a wholly new style and new effects. The style thus evolved matured with extraordinary rapidity and then began a long and gradual decline. If we take the baptistery of the Orthodox and the tomb of Galla Placidia, both at Ravenna, and dating from about 450 A.D., as the earliest examples of the style, less than a century elapsed between its birth and its culmination in the unsurpassed church of Hagia Sophia at Constantinople (532-38 A.D.). This masterpiece was never equaled in scale or magnificence thereafter. Five centuries later, however, in the church of Saint Mark at Venice (1047-71; the façade later) the style flowered in a new masterpiece of great beauty, at the hands of Greek and Italian artists. No other extant example approaches these two in magnificence and artistic merit. During the reign of Justinian several other splendid churches were built at Constantinople and Jerusalem, but even these were far inferior to Hagia Sophia. Except in the one instance of Saint Mark's, all the later churches were relatively small in dimension and timid in construction.

Characteristics.-The dominant feature of the style is the central dome on pendentives. The pendentive is a device by which a circular dome can be erected upon four or more isolated supports, instead of upon a continuous circular wall. It consists of a triangular portion of a sphere comprised between two adjacent arches and a horizontal circle touching their summits. Four such surfaces carried by four arches bounding a square meet at the top in a circle to form the base of the dome, or of a circular drum upon which the dome is to rest. means of eight piers, with their arches and pendentives, the dome may be built over an

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octagonal space. In either case the openings between the piers allow the floor-plan to be extended in any direction, so that the dome may be used in connection with almost any type of ground-plan; whereas in previous styles it had been almost wholly confined to circular structures, as in the Pantheon at Rome. The Byzantine plans were therefore very varied, and were vaulted throughout in brick. The construction of these domed and vaulted buildings, which were nearly all ecclesiastical, was based generally on the Roman principle of massive internal piers and intermediate columnar supports; but the Byzantine columns carried arches instead of entablatures like the Roman. External buttressing above the roofs of side-aisles or other low portions was another Roman feature derived from bath-halls and the Basilica of Maxentius. Roman also were the system of wall decoration by incrustation with slabs of richly veined marble, the use of marble in decorative patterns for floor-pavements, and the employment of monolithic column-shafts of polished granite, porphyry and marble, at once structural and decorative. On the other hand, the Byzantine conception of interior adornment as a covering of all surfaces, both of walls and vaults, with a veneer of perfectly flat decoration in color, broken up into minute units, was distinctly Oriental. All carving in high relief was replaced by delicate all-over patterning in very flat low relief, and above the marble wainscoting the walls and vaults were covered with mosaic of minute glass tessera (see MOSAIC) in brilliant colors usually on a gold ground. These mosaics were partly pictorial, representing Christ, saints, apostles and other religious or Biblical subjects, and partly conventional patterns. The Roman types of capital were replaced generally by new types of simpler mass covered with flat-relief carving of foliage and basketwork, and impost-blocks were often introduced between the caps and the heavy arches which they carried.

History and Monuments.-The germs of the style are seen in certain early Christian buildings in Syria and in Diocletian's palace at Spalato, which was probably built by Syrian or Byzantine workmen; more clearly in two 5th century buildings at Ravenna the baptistery of the Orthodox, having a dome over an octagonal substructure and the tomb of Galla Placidia, a cruciform edifice with a square "lantern" rising above the arms at their intersection, crowned by a dome on rudimentary pendentives. Doubtless, however, the original prototype of one class of Byzantine churches having a central square or octagon surrounded by an aisle is to be found in two Roman buildings erected by Constantine - the baptistery of the Lateran and the tomb of Constantia (Santa Costanza). The roof of the high central part of the former was of wood; of the latter, a masonry dome. The evolution of the central space with a dome on eight supports may be traced through early examples in Syria to Saint Sergius at Constantinople (520 A.D.) where alternate sides of the octagon were occupied by open columnar niches or apsidioles projecting into the surrounding aisle, thence to San Vitale at Ravenna (525 or 527), where there are six such apsidioles; the easternmost bay being in both these churches extended to form a chancel and apse;

and finally to its culmination in the new type of plan seen in Hagia Sophia (The Divine Wisdom, often called "Saint Sophia"; now a mosque). This extraordinary edifice, the work of two architects from Asia Minor, Anthemius and Isodorus, was built under the orders of Justinian in six years (532-38) to replace an earlier church destroyed by fire during a racecourse riot. It occupies a broad rectangle, measuring nearly 300 by 240 feet, and consists of a central nave 243 by 115 feet covered by a dome 107 feet in diameter and 180 feet high, and two half-domes of 100 feet span opening into the two transverse arches of the four that carry the dome. This hall is flanked by two vast aisles, 60 feet wide, each divided into three parts by two massive buttresses which rise above the roofs of the two-storied aisles. This triple division of the aisles by transverse buttressmasses which rise above the aisle roofs is plainly derived from the traditional form and construction of the Roman thermæ, probably through the intermediary Basilica of Maxentius of the early 4th century. A narthex across the west front preceded by an atrium or fore-court, and the projection of the apse at the east end, make up the total length of 300 feet. Open columnar apsidioles expand the semi-circular ends of the nave, and recall the six similar apsidioles between the piers of San Vitale at Ravenna. The interior is resplendent with polished columns of costly marble, verd-antique and porphyry, with marble wainscot and superb mosaics, though all human figures have been concealed by gilding and paint on account of Moslem prejudices. The furniture of the church, which was of unrivaled cost and splendor, disappeared centuries ago. In this stupendous work we seem to see the plan of Saint Sergius cut in two and between the two halves an immense square interposed, covered by a gigantic dome on pendentives rising far above the rest of the building. On the other hand, the cruciform type first shown in the tomb of Galla Placidia culminated, also in Justinian's time, in the church of the Apostles at Constantinople. This had five domes, one on each arm of the cross and a central dome dominating the whole. This splendid church was demolished in 1463 by the conquering Sultan Mehemet II, but it had already served as the model for the builders of Saint Mark's at Venice.

With the exception of this last named church, none of the other Byzantine churches of Constantinople was of large size. The only other church of Justinian's time that has survived to our day is that of the Holy Peace, Hagia Eirené (miscalled "Saint Irene"), now used as a museum of arms. It is, however, a poor example, destitute of all embellishments, and is really a late (8th century?) and hasty reconstruction of the original edifice. With its two domes it may have served as the model for the Cathedral of Cahors, France. The later examples of the style in Constantinople were relatively small in scale, sometimes complex in plan, with small domes on high drums (Saint Theodore, Pantokrator, Moné tes Choras, etc.). About 40 of these small churches are extant, mostly transformed into mosques; and only one of them retains any considerable part of its original decorations. This one is the Moné tes Choras, now known as Kahrié Jami, dating probably from the 11th or 12th century, with a

narthex adorned with mosaics and frescoes which, uncovered about 1880, the Turks have allowed to remain exposed. There are a number of late Byzantine churches in Athens - all of singularly small size and at Salonica several of various dates (Saint George, Saint Elias, Saint Bardias, Saint Sophia); besides interesting monastic groups in Macedonia, at Meteora and on Mount Athos. In Russian Armenia (Ani, Etchmiadzin, etc.) the style took on a distinct provincial character, with stone pyramids instead of domes as the outer form of the cupola on a high drum, and often with highly interesting carved interlace ornament. The singular and barbarously fantastic forms of shurches at Moscow, Kiev and other Russian cities (e.g., the Saint Basil in the Kremlin in Moscow) are remotely derived from the tall-drum domed "lanterns" of the late Byzantine type. Near the middle of the 11th century the destruction by fire of the church of Saint Mark at Venice turned the attention of the Venetians toward Constantinople as the source from which to obtain architects and decorators capable of rebuilding worthily the venerated shrine of the evangelist. Architecture was at that time in Italy only beginning to revive from its low estate, and the native artists and the native art appeared inadequate for the task in hand, except as they were guided and assisted by Byzantine architects. The new church, measuring about 220 by 180 feet, was erected on the cruciform plan of the Holy Apostles' Church at Constantinople, with five domes, of which the central was slightly larger than those on the four arms. The very active Venetian commerce with the East brought in an extraordinary wealth of artistic material — antique columns, veined marbles, carvings from ruined or dismantled churches and with these and the embellishments of mosaic by Greek artists and their Italian pupils, as well as by later additions of sculpture and furnishings, the interior was made resplendent beyond any other church in Italy or western Europe. Lacking the overwhelming majesty and unity of Hagia Sophia, it has nevertheless an extraordinary beauty of its own. The main construction was completed in 1071; the domed narthex dates from the 12th century, with the extraordinary and marvelously picturesque façade; the wooden exterior domes and Gothic pinnacles were added in the 15th century: some of the mosaics are modern. Unlike the Byzantine churches of the East, which almost wholly lack external embellishment, Saint Mark's is revetted externally with paneling of fine marble. Strange to say, it was never copied or imitated, except in the Romanesque church of Saint Front at Périgueux (France), which however is totally lacking in the embellishments of marble and mosaic that make up so much of the splendor of the Venetian model. Quite as surprising is the fact that Hagia Sophia, the noblest of all Byzantine monuments, remained absolutely unique and unimitated until the Turkish conquest. It was the Turkish mosquebuilders who seized upon its superb possibilities and developed from them a new and splendid type of architecture for their own requirements (see MOHAMMEDAN ART).

An interesting lateral branch of Byzantine architecture is seen in the monasteries erected by Coptic Christians in Egypt, in the 6th-9th