It is noteworthy that the architects who built S. Sophia as well as the historians who chronicle the work, all, so far as their birth-places are known, come from Syria and Asia Minor. The flourishing city of Ephesus was one of the great centres of the transformation of the art of building; and it was from the neighbouring cities of Tralles and Miletus, that Anthemius and Isidorus came to Constantinople. Of the two master builders who appear to have been employed together by Justinian, it seems clear, from Procopius and the other writers, that Anthemius was more especially concerned in the preparation of the first draft or model, and that Isidorus, by birth a Milesian, was associated with him in the conduct of the works. “Anthemius,” says Paulus, “skilled in setting out a plan, laid the foundation.” “Anthemius was the man who devised and worked at every part,” writes Agathias, and this author gives some account of his life. “Now this Anthemius was born at Tralles, and he was an inventor of machines; one of those who apply designs to material, and make models and imitations of real things. He was distinguished in this and had reached the summit of mathematical knowledge, just as his brother Metrodorus was distinguished in letters. Besides these there were three other brothers, Olympus, famous for his knowledge of law, and Dioscorus and Alexander, both skilled in medicine. Of these Dioscorus lived in his native land and Alexander in Old Rome. But the fame of the skill of Anthemius and Metrodorus reached the emperor, and they were invited to Constantinople, where they spent the rest of their lives, each presenting wonderful examples of his skill. One taught letters; the other raised wonderful buildings throughout the city and in many other places; these, I think, even if nothing were said about them, as long as they remained unharmed, would be sufficient to win for him perpetual glory.” Stories of his mechanical ingenuity are told by Agathias one of which is as follows. Anthemius had a quarrelsome neighbour whose room overhung his ground. He placed here large kettles of water, with an arrangement of leather pipes and a tube like a trumpet up to the projecting part; and making the other parts secure, “he heated the water so that the whole thing burst up like an earthquake.” As to the scheme prepared by the master builders for the building, an examination of the evidence seems to suggest the following antecedent conditions and governing ideas. 1. The ground levels required a short and wide church (_ante_, p. 186). 2. An old western apse possibly suggested the western hemicycle of the new church (_ante_, p. 19). 3. The plan, while a direct outcome of traditional forms as we have shown, seems a synthesis of the three types which were then current; the Basilican like S. John Studius; the square church with a dome like S. Sergius, and the cross plan of the Church of the Apostles.