Though as it has already been said there is but one church which has survived the Turkish conquest without ever ceasing to be used for its divine purpose, there are very many buildings in Constantinople still remaining, with more or less change, that were once hallowed to the worship of the Church of Christ. Very many have perished, the most notable among them that Church of the Holy Apostles, which was destroyed by Mohammed the Conqueror to build the great mosque which bears his name. But those which still remain were among the chiefest wonders of the City of the Emperors, and there is not one of them which does not deserve an extensive study. The volumes that have been written on Byzantine architecture cannot be compressed into a few pages. It must suffice to recall what are the chief characteristics of the style which may still be seen in its perfection at Constantinople, as at Salonica. The origin of what had so wide an extension over the East, of the art which made a new departure under Constantine, and a still more important one under Justinian, is simply the basilica, the law court of ancient Rome. A long nave and aisles separated by rows of pillars, surmounted by a flat roof and ending in an apse: that is the familiar type of which a splendid example built under Byzantine influence is to be found in the church of S. Apollinare Nuovo at Ravenna. To this simple design the East added the development of the dome. In the sixth century the domical style decisively replaced the basilican; and nowhere can the transition be more clearly traced than in Constantinople. [Illustration: CAPITAL FROM RAVENNA SHOWING EARLY FORM OF IMPOST _Metal Socket_ CAPITALS FROM S. SOPHIA (IMPOST ABSORBED)] We have then, in our examination of the still remaining specimens of Byzantine art, to observe first the basilicas, then the combination of basilica with dome, then the examples of the completed domical style. But this is by no means all. Byzantine art, in the carving of capitals, in the creation of the impost-capital, in its achievement of "teaching the column to support the arch," in sculpture, in bronze work, in the detail of inscriptions, and above all, in mosaic, is worth the most attentive study, and happily in spite of time, war and barbarism, Constantinople still furnishes a fruitful field for the student.