Mysteriously secured by nature and doubly so after the failure of the Roman administration, Ravenna was the death-bed of the empire and its tomb. To her the emperor Honorius fled from Milan in the first years of the fifth century; within her walls Odoacer dethroned the last emperor of the West, founded a kingdom, and was in his turn supplanted by Theodoric the Ostrogoth. It was from her almost impregnable isolation that the attempt was made by Byzantium--it seemed and perhaps it was our only hope--to reconquer Italy and the West for civilisation; while her fall before the appalling Lombard onset in the eighth century brought Pepin into Italy in 754, to lay the foundation of a new Christendom, to establish the temporal power of the papacy, and to prophesy of the resurrection of the empire, of the unity of Europe. But though it is as the imperishable monument of those tragic centuries that we rightly look upon Ravenna: before the empire was founded she was already famous. It was from her silence that Caesar emerged to cross the Rubicon and all unknowing to found what, when all is said, was the most beneficent, as it was the most universal, government that Europe has ever known. In the first years of that government Ravenna became, and through the four hundred years of its unhampered life she remained, one of its greatest bulwarks. While upon its failure, as I have said, she suddenly assumed a position which for some three hundred and fifty years was unique not only in Italy but in Europe. And when with the re-establishment of an universal government her importance declined and at length passed away, she yet lived on in the minds and the memory of men as something fabulous and still, curiously enough, as a refuge, the refuge of the great poet of the new age; so that to-day, beside the empty tombs of Galla Placidia and Theodoric, there stands the great sarcophagus which holds the dust of Dante Alighieri. We may well ask how it was that a city so solitary, so inaccessible, and so remote should have played so great a part in the history of Europe. It is to answer this question that I have set myself to write this book, which is rather an essay _in memoriam_ of her greatness, her beauty, and her forlorn hope, than a history properly so called of Ravenna. But if we are to come to any real understanding of what she stood for, of what she meant to us once upon a time, we must first of all decide for ourselves what was the fundamental reason of her great renown. I shall maintain in this book that the cause of her greatness, of her opportunity for greatness, was always the same, namely, her geographical position in relation to the peninsula of Italy, the Cisalpine plain, and the sea. Let us then consider these things.