Francesco di Giorgio of Siena, who was an excellent sculptor and architect, made the two bronze angels that are on the high-altar of the Duomo in that city. These were truly very beautiful pieces of casting, and he finished them afterwards by himself with the greatest diligence that it is possible to imagine. This he could do very conveniently, for he was endowed with good means as well as with a rare intelligence; wherefore he would work when he felt inclined, not through greed of gain, but for his own pleasure and in order to leave some honourable memorial behind him. He also gave attention to painting and executed some pictures, but these did not equal his sculptures. He had very good judgment in architecture, and proved that he had a very good knowledge of that profession; and to this ample testimony is borne by the palace that he built for Duke Federigo Feltro at Urbino, which is commodiously arranged and beautifully planned, while the bizarre staircases are well conceived and more pleasing than any others that had been made up to his time. The halls are large and magnificent, and the apartments are conveniently distributed and handsome beyond belief. In a word, the whole of that palace is as beautiful and as well built as any other that has been erected down to our own day. Francesco was a very able engineer, particularly in connection with military engines, as he showed in a frieze that he painted with his own hand in the said palace at Urbino, which is all full of rare things of that kind for the purposes of war. He also filled some books with designs of such instruments; and the Lord Duke Cosimo de' Medici has the best of these among his greatest treasures. The same man was so zealous a student of the warlike machines and instruments of the ancients, and spent so much time in investigating the plans of the ancient amphitheatres and other things of that kind, that he was thereby prevented from giving equal attention to sculpture; but these studies brought him and still bring him no less honour than sculpture could have gained for him. For all these reasons he was so dear to the said Duke Federigo, whose portrait he made both on medals and in painting, that when he returned to his native city of Siena he found his honours were equal to his profits.