Many churches subsequently built, however, were erected upon the sites of these older ones and have fragments of the older buildings incorporated in them. Of such are the churches of St. Germain des Prés, in Paris, and Notre Dame du Port, at Clermont. Under Charlemagne, a revival of art was attempted, the chief building constructed by him being a reproduction of St. Vitale, of Ravenna, in which he employed sculpture and ornament torn from the original structure, and fragments from the edifices of ancient Rome; but this effort soon died away, and the period intervening between the eighth and tenth centuries was totally lacking in any architectural production of merit. As the Roman principles of architecture had been taken Eastward and gradually transformed into a new style at Byzance, so also in the West they had been the forerunners of another method of building, but proportionately different in accordance with the character, customs, and race of the Western populations. The basilica formed, as it had in the East, the model upon which all church architecture was designed, the nave, transept, aisles, and apse being all retained in this new class of buildings, but many of the building methods were new, and the details of their decoration differed considerably from the precise proportions and Classic graces of the buildings of Rome. The result exhibits a curious contrast between the barbaric ornament and the scientific construction, which advanced throughout the style in the genuine efforts which were made to progress in the art of building. Starting thus at the decadence of Classic art, with a Classical building as the original type for their churches, the Romanesque architects took up each of the parts combining in its formation, and sought to improve or elaborate each, in pursuance of certain ends, arising from local necessities. There is virtually no point where Romanesque ends and Gothic commences, to give due reason for the conventional divisions of historians, for the one style melts into the other in the continual progress in the study of the principles of construction which was steadily effected throughout both styles. They differ chiefly in that, during the two centuries prior to the thirteenth century, the pointed arch was rarely used, and that the influence of the Classic decadence is more apparent in the buildings of the earlier period. After this, the pointed arch became universal, and the whole style becoming entirely distinct from its derivation, the ornament and detail, quite unlike anything which had come before, it may be said that a new style had been created. This new style, which has been called Gothic, continued to be developed until the fifteenth century, when its principles became exaggerated, and it died out at the extreme point to which they could be pushed.