These walls are visible; they still hold firm.  Unquestionably, they could not resist our modern cannon, for if the ancients built better than we do, we destroy better than they did; this is one thing that must in justice be conceded to us.  Nevertheless, we cannot but admire those masses of peperino, the points of which ascend obliquely and hold together without mortar.  Originally as ancient as the city, these ramparts were destroyed to some extent by Sylla and repaired in opus incertum, that is to say, in small stones of every shape and of various dimensions, fitted to one another without order or regularity in the layers, as though they had been put in just as they came.  The old structure dated probably from the time of Pompeian autonomy—­the Oscans had a hand in them.  The surrounding wall, at the foot of which there were no ditches, would have formed an oval line of nearly two miles had it not been interrupted, on the side of the mountains and the sea, between the ports of Stabiae and of Herculaneum.  These ramparts consisted of two walls—­the scarp and counterscarp,—­between which ran a terraced platform; the exterior wall, slightly sloping, was defended by embrasures between which the archer could place himself in safety, in an angle of the stonework, so soon as he had shot his arrow.  The interior wall was also crested with battlements.  The curvilinear rampart did not present projecting angles, the salients of which, Vitruvius tells us, could not resist the repeated blows of the siege machinery of those days.  It was intersected by nine towers, of three vaulted stories each, at unequal distances, accordingly as the nature of the ground demanded greater or less means of defence, was pierced with loopholes and was not very solid.  Vitruvius would have had them rounded and of cut stone; those of Pompeii are of quarried stone, and in small rough ashlars, stuck together with mortar.  The third story of each tower reached to the platform of the rampart, with which it communicated by two doors.

Notwithstanding all that remains of them, the walls of Pompeii were no longer of service at the time of the eruption.  Demolished by Sylla and then by Augustus, shattered by the earthquake, and interrupted as I have said, they left the city open.  They must have served for a public promenade, like the bastions of Geneva.

Eight gates opened around the city (perhaps there was a ninth that has now disappeared, opening out upon the sea).  The most singular of all of them is the Nola gate, the construction of which appears to be very ancient.  We there come across those fine cut stones that reveal the handiwork of primitive times.  A head considerably broken and defaced, surmounting the arcade, was accompanied with an Oscan inscription, which, having been badly read by a savant, led for an instant to the belief that the Campanians of the sixth century before Jesus Christ worshipped the Egyptian Isis.  The learned interpreter had read:  Isis propheta (I translate it into Latin, supposing you to know as little as I do of the Oscan tongue).  The inscription really ran, idem probavit.