One of the simplest, but most extensive of those primitive strongholds, is Fort Hill, Ohio. The defences occupy the summit of a height, elevated about five hundred feet above the bed of Bush Creek, which flows round two sides of the hill, close to their precipitous slope. Along the edge of this hill a deep ditch has been cut, and the materials taken from it have been piled up into an embankment, rising from six to fifteen feet above the bottom of the ditch. In its whole extent the wall measures eight thousand two hundred and twenty-four feet, or upwards of a mile and a half in length; and encloses an area of forty-eight acres, now covered with gigantic forest-trees. One of them, a chestnut, measured twenty-one feet, and an oak, though greatly decayed, twenty-three feet in circumference, while the trunks of immense trees lay around in every stage of decay. Such was the aspect of Fort Hill, Ohio, a few years ago, and it is probably in no way changed now. Dr. Hildreth counted eight hundred rings of annual growth in a tree which grew on one of the mounds at Marietta, Ohio; and Messrs. Squier and Davis, from the age and condition of the forest, ascribed an antiquity to its deserted site of considerably more than a thousand years. In their present condition, therefore, the walls of “Fort Hill” are ruins of an older date than the most venerable stronghold of the Normans of England; and we see as little of their original completeness, as in the crumbling Norman keep we are able to trace all the complex system of bastions, curtains, baileys, buttress-towers, and posterns, of the military architecture of the twelfth century. Openings occur in the walls, in some places on the steepest points of the hill, where access is impossible; and where, therefore, we must rather suppose that platforms may have been projected to defend more accessible points. The ditch has in many places been cut through sandstone rock as well as soil; and at one point the rock is quarried out so as to leave a mural front about twenty feet high. Large ponds or artificial reservoirs for water have been made within the enclosure; and at the southern point, where the natural area of this stronghold contracts into a narrow and nearly insulated projection terminating in a bold bluff, it rises to a height of thirty feet above the bottom of the ditch, and has its own special reservoirs, as if here were the keep and citadel of the fortress: doubtless originally strengthened with palisades and military works, of which every trace had disappeared before the ancient forest asserted its claim to the deserted fortalice. Here then, it is obvious we look on no temporary retreat of some nomadic horde, but on a military work of great magnitude; which, even with all the appliances of modern engineering skill, would involve the protracted operations of a numerous body of labourers, and when completed must have required a no less numerous garrison for its defence.