What Evander showed to his visitor, as we shall presently see, comprised the whole site of the heart and life of the city as it was to be, all that lay under the steep sides of the three almost isolated hills, the Capitoline, Palatine, and Aventine. The poet knew that he need not extend their walk to the other so-called hills, which come down as spurs from the plain of the Campagna,--Quirinal, Esquiline, Caelian. Densely populated as those were in his own day, they were not essential organs of social and politics life; the pulse of Rome was to be felt beating most strongly in the space between them and the river where too the oldest and most cherished associations of the Roman people, mythical and historical, were fixed. I propose to take the reader, with a single deviation, over the same ground, and to ask him to imagine it as it was in the period with which we are concerned in this book. But first, in order to take in with eye and mind the whole city and its position, let us leave Aeneas, and crossing to the right bank of the Tiber by the Pons Aemilius,[5] let us climb to the fort of the Janiculum, an ancient outwork against attack from the north, by way of the via Aurelia, and here enjoy the view which Martial has made forever famous: Hinc septem dominos videre montes Et totam licet aestimare Romam, Albanos quoque Tusculosque colles Et quodcunque iacet sub urbe frigus. No one who has ever stood on the Janiculum, and looked down on the river and the city, and across the Latin plain to the Alban mountain and the long line of hills--the last spurs of the Apennines--enclosing the plain to the north, can fail to realise that _Rome was originally an outpost of the Latins_, her kinsmen and confederates, against the powerful and uncanny Etruscan race who dwelt in the undulating hill country to the north. The site was an outpost, because the three isolated hills make it a natural point of defence, and of attack towards the north if attack were desirable; no such point of similar vantage is to be found lower down the river, and if the city had been placed higher up, Latium would have been left open to attack,--the three hills would have been left open to the enemy to gain a firm footing on Latin soil. It was also, as it turned out, an admirable base of operations for carrying on war in the long and narrow peninsula, so awkward, as Hannibal found to his cost, for working out a definite plan of conquest. From Rome, astride of the Tiber, armies could operate on "interior lines" against any combination--could strike north, east, and south at the same moment. With Latium faithful behind her she could not be taken in the rear; the unconquerable Hannibal did indeed approach her once on that side, but fell away again like a wave on a rocky shore. From the sea no enemy ever attempted to reach her till Genseric landed at Ostia in A.D. 455.