Early Christian or The Emperor Constantine (328 a.n.) made christianity legal. Throughout the preceding four centuries Christian art had been slowly developing. Hidden and secret, its early forms were domestic or sepulchral. With the freedom of worship possible under the enlightened Con stantine, the Christians appropriated for their religious edifices all that was adaptable in Roman architecture. The early Christians translated in their liturgical forms the organi zation that they had become habituated to in the conduct of Roman affairs; thus the Basilica in which the business of the Empire had been transacted served as a basis for a proper hous ing for the performance of the public rites of Christians. The broad and lofty nave of the basilica with its single or double aisles, pro vided ample space for worshippers. Above the nave columns rose the lofty clerestory walls pierced with windows. Immense wooden trusses carried the roof of the nave. At the far end was the apse with seats for the clergy, and in front of the apse was the altar. Generally, a forecourt, surrounded by a covered arcade, preceded the basilica proper. This was connected with the church by a porch. One of the most impressive places of worship in the world to-day is the rebuilt basilica of Saint Paul without the walls at Rome, erected in 386 A.D. by Theodosius. In the general survey of architecture this edifice is of peculiar importance because the arches of the nave arcade are turned from column to column without the use of an intervening en tablature between the capital of the column and the spring of the arch. The first known case of such use of columns as arch bearers was in the palace of Diocletian at Spalato. This nave arcade motif, modified by the struc tural changes of the Romanesque and Gothic periods finally flowered into the wonderful nave arcade conceptions of the ecclesiastical master pieces of Amiens and Rheims.
Under Constantine, the Greek city Byzantium, renamed Constantinople, be came the chief city of Christendom. Under Justinian, 527 to 565 A.D., the structural under takingg of the Eastern Empire developed an extraordinary activity especially in the building of churches. Syria, Dalmatia, Macedonia and Ravenna were scenes of architectural industry, for the most part under the direction of Asiatic Greeks. Engrafted upon the Latin type of church — the basilica with its three aisles and wooden roof — were certain traditional vault ing methods in brick and stone of Asiatic origin. The most notable characteristic of this structural method is the central dome on pen dentives, a device by which a circular vault can be erected upon a series of isolated sup ports. By this scheme of dome construction polygonal chambers were built which could be monumentally roofed and would permit the floor plan to be extended indefinitely in any direction. The Byzantine plans are of great variety and enable the designer to achieve results which for propriety of scale and effectiveness of decora tion have never been excelled. The great masterpiece of the style is Hagia Sophia, often called "Saint Sophia,* built tinder the orders of Justinian, 532-538 A.D., to replace an earlier Basilican building. This huge church, one of the greatest of the world's art masterpieces, marks the culmination of the style. It was followed by a long and gradual decline in artistic value. Some five centuries later a re crudescence of the style appears in the church of Saint Mark at Venice (1047-71), where a combination of Greek and Italian artists pro duced a masterpiece of great beauty which sub sequently influenced the plan of the Roman esque church of Saint Front at Perigueux, France. The Romanesque cathedral of Cahors,
France, was probably inspired by the Justinian church of the Holy Peace, Hagia Irene. All church building, even the latest and richest Gothic has the exterior for its chief splendor. The Byzantines apparently gave little thought to the embellishment of the exterior of their buildings, and lavished all of their decorative effort upon the interior. This style, invented in practically a single effort, a result not known to have been achieved anywhere else in the history of art, has prevailed ever since through out the lands extending from the Red Sea northward through Russia.
Sasanian and Contem poraneous with the development of Roman and Byzantine rule under the Sasanian dynasties (227-641 A.D.) an art was developed in Western Asia based upon Hellenistic columnar pre cedent, combined with vaulted methods, the knowledge of which had its origin in the subterranean vaults and fragment domes of Mesopotamia. The royal palace at Ctesiphon, with its great eliptically arched hall, is a monumental example of the remarkable tenacity with which these Oriental peoples held fast to their own artistic traditions. The two Oriental lines of architectural influence lead, one toward the Far East, expressing itself in the types found in India and China ; and the other in the Levant, embracing practically all of the countries which ultimately came under the faith of Islam. The architectural styles that followed in the wake of the Mohammedan conquests were marked by certain common characteristics which differentiate them from the contemporary Christian styles. The decora tive consideration was ever controlling. Con struction was relegated to a secondary place. Restricted by the Mohammedan canon there is an absence of illustrative decoration and sculp ture throughout Arabic, Persian, Turkish and Indian buildings. The profuse conventional decoration that necessarily took the place of humanistic representation showed a great love for minute surface ornament. The mosque and tombs throughout the Arabic countries of the Mediterranean exhibit frequently a remarkable degree of decorative elegance. In northern Africa, the Arabs restricted construction and gave free play to decorative license. This par ticular phase of architectural expression is known as the Moresque style, horseshoe cusped arches were substituted for the simpler and structural architectural forms. Plaster relief entirely took the place of more endurable materials. Arabic architecture attained a re markable splendor, curiously enough, not in Africa, but in Spain, the southern portion of which was overrun by the Moors, 710-713 A.D. ; where petty kingdoms were developed most im portant of which were Granada, Seville and Toledo; until the capture of Granada in 1492 when the Moorish rule in Spain was ended, there was an extraordinary activity in build ing. Mosques, castles, acqueducts were reared and the climax of the style was reached . in the construction of the great mosque at Cordova, the Giralda. at Seville and the Al hambra at Granada, the latter universally con sidered to be the masterpiece of Hispano Moresque art.