Some had mouldered away, by the slow hand of ruthless time; and yet more had been pulled down for the sake of their materials, which now filled a more useful if less glorious station, in the enclosures of tilled fields, and the walls of rustic dwellings. From such a fate the watchtower of Usella had been saved by several accidents. Its natural and artificial strength had prevented its sack or storm during the earlier period of its existence—the difficulty of approaching it had saved its solid masonry from the cupidity of the rural proprietors—and, yet more, its formidable situation, commanding one of the great hill passes into Cisalpine Gaul, had induced the Roman government to retain it in use, as a fortified post, so long as their Gallic neighbors were half subdued only, and capable of giving them trouble by their tumultuous incursions. Although it had consisted, therefore, in the first instance, of little more than a rude circular tower of that architecture called Cyclopean, additions had been made to it by the Romans of a strong brick wall with a parapet, enclosing a space of about a hundred feet in diameter, accessible only by a single gateway, with a steep and narrow path leading to it, and thoroughly commanded by the tower itself. In front, this wall was founded on a rough craggy bank of some thirty feet in height, rising from the main road traversing the defile, by which alone it could be approached; for, on the right and left, the rocks had been scarped artificially; and, in the rear, there was a natural gorge through which a narrow but impetuous torrent raved, between precipices a hundred feet in depth, although an arch of twenty foot span would have crossed the ravine with ease. Against the wall at this point, on the inner side, the Romans had constructed a small barrack with three apartments, each of which had a narrow window overlooking the bed of the torrent, no danger being apprehended from that quarter. Such was the place into which Crispus had retreated, under the guidance of one of the Etruscan conspirators, after the attack of the Roman infantry; and, having succeeded in reaching it by aid of their horses half an hour before their pursuers came up, they had contrived to barricade the gateway solidly with some felled pine trees; and had even managed to bring in with them a yoke of oxen and a mule laden with wine, which they had seized from the peasants in the street of the little village of Usella, as they gallopped through it, goading their blown and weary animals to the top of their speed. It was singularly characteristic of the brutal pertinacity, and perhaps of the sagacity also, of Caius Crispus, that nothing could induce him to release the miserable Julia, who was but an incumbrance to their flight, and a hindrance to their defence.