_Mudejar_ architecture was no mushroom style--on the contrary, it had its slow rise and fall, and it evinces a state of constant and continual transformation. The oldest edifice now in existence is perhaps the church of San Roman at Toledo. Those who would study the manner in which the _mudejar_ architecture has been modified in turn by Roman, Byzantine, and Gothic influences, would do well to follow the advice of Lamperez, and group their researches on geographical lines. Catalonia, Castille, Andalusia, Aragon and Toledo, and so on. In Aragon are to be found the strongest and most splendid Mohammedan influences that Spain can show; while in Galicia these influences are, as it were, but momentary. Even Granada can show nothing to compare with the glories of Aragon, with its towers of Teruel, Daroca, and Saragossa, and with its churches of Calatayred. But before Spain gave birth to her _mudejar_ architecture, and long before the Moors set foot upon her shores, her Christian art owed more to the East than to the West, for it was as much Byzantine as Roman. Byzantine art dates its origin from the year 330, when Constantine moved his court from Rome to Constantinople, to a town on the borders of Asia and Europe. Constantinople, by its geographical position, was the natural meeting-point of Persians, Indians, Armenians, and Syrians. All these influences, as well as those of Asia Minor, were now brought to bear upon the Christianised pagan art of Rome. The result was the birth of Byzantine art. How Byzantine art was carried to the furthest corners of the Christian world it is not difficult to see. Constantinople had become the centre of the Roman Empire. From her shores there poured forth warriors, traders, missionaries to every part of the earth. Byzantine architecture borrowed her massive cupolas, supported by square pillars over a square edifice, from Persia, and from Syria she borrowed her floral ornamentation; while her love of colour, of brasses and mosaics, is traceable to the influence of all the Oriental centres where wealth and ostentation abounded. The greatest monument of Byzantine art is, of course, St. Sophia’s (now a mosque) at Constantinople, which the Emperor Justinian erected between 527 and 565. Here we see the decadent art of classic Rome transformed and vivified by Asiatic influences. In the seventh century, the agitation against the Iconoclasts (destroyers of images), in the reign of the Emperor Leo the Isaurian[99] (813-821), resulted in a wide diffusion of Byzantine influences throughout the western provinces of the great Roman Empire. Spain, herself a province, became affected.[100]