BYZANTINE ARCHITECTURE. The typical form of B. A., at least as applied to ecclesi astical purposes, was fixed by the church of St. Sophia, which still exists as the great mosque of Constantinople. It was built, or rather rebuilt, by the orders of Justinian, the architects being Anthemius of Tralles, and Isodorus, the elder, of Miletus, and com pleted 537 A.D. Though the largest and most magnificent, the church of St. Sophia was but one of 25 churches which were erected in the capital, and of a vastly greater num ber of ecclesiastical structures with which the provinces were adorned by the pious emperor. The style thus introduced largely- influenced the architecture even of western Europe; and iu St. Mark's at Venice, the churches at Ravenna and elsewhere on the Adriatic, and even in the cathedral of Aix-la-Chapelle, we have examples of churches almost purely Byzantine. The fundamental principle in the construction of Byzantine churches was an endlessly varied application of the Roman arch, whilst its exhibition in the form of the cupola was their most characteristic feature. In the St. Sophia, as was generally the case, the cupola covered the principal central portion of the church, and was supported by strong and lofty pillars, bound together by bold arches. To this cen tral space were usually joined others of smaller size, which were covered by half-cupo las or arches of more ordinary construction. Though frequently in the form of a Greek cross, with the great cupola rising in the center, and smaller or semi-cupolas surmount ing the four arms, neither this nor any other plan was consistently adhered to in Byzan tine churches. The windows were always semicircular, similar to those in the Romanic
churches of Germany, and in our own Saxon or early Norman churches; but the doors were frequently square-headed, after the classical model. Many of the details, such as the square capitals tapering downwards, and the bold projecting moldings ornamented with foliage, seem to have owed their origin entirely to the ingenuity of Byzantine archi tects. The earlier Byzantine churches were profusely ornamented with mosaics, which, after the admixture of the Gothic element, and the adoption of the pointed arch, gave place to fresco-paintings. The constant use of the apse (q.v.) is, after the cupola, per haps their most marked feature. The following division into periods, though, like most divisions of the kind, somewhat arbitrary, has the authority of M. Couchaud,•an emi nent French architect, in its favor, and is, apparently, adopted by Parker: 1. From the time of Constantine to the middle of the 6th c.; 2. Y'rom the beginning of Justinian's reign down to the 11th e., which comprises the greater part of the existing buildings of the pure Byzantine type; 3. From the 11th c. to the conquest of Greece by the Turks, when the influence of the Venetian conquests is apparent in the intermixture of Italian and Gothic details and characteristics.