Away in the opposite direction stretched the Appian Way, and in the year 64 the beautiful tomb of Caecilia Metella, which is so familiar in picture, stood as perhaps the noblest among the multitude of patrician tombs. The Apostle Paul certainly passed close by it on his way from Puteoli. The aqueduct, of which so many arches still meet the eye as you cross the Campagna, was the work of Nero's predecessor, Claudius, and it still bears his name--the Aqua Claudia. Where now you go out of the gate to St. Paul's Outside-the-Walls there stood--more free and visible than now--that pyramid of Cestius, close to whose shadow lie the graves of the English Shelley and Keats. There was no gate at this spot in the days of Nero, for the great wall, of which so many portions--more or less restored--are still conspicuous, had no existence till a much later date, when the empire was already tottering to its fall, and when Aurelian was driven to recognise that the heart of the empire, after remaining secure for centuries, must at last look to be assailed. There was, it is true, an inner wall of ancient date (to be seen upon the plan) which had enclosed the "Seven Hills" before Rome was mistress of more than her own small environment. But the city had long ago overflowed this boundary, and the newer quarters lay as open to the country as do our own modern cities. How far the suburbs stretched, or precisely how far Rome proper extended, in the days of Nero, is no easy matter to decide. We shall in all probability be near the mark if we accept the line of the later wall of Aurelian as practically the limit of what might be included in the "Metropolitan Area." The total circumference of the whole city would be about twelve English miles, a circuit which fell somewhat short of that of Alexandria and probably of Antioch, although in actual importance these cities took but the second and third rank respectively.