Finally, there remains to be taken into consideration those great earthworks on the hills which have been specially classified as having been undoubtedly raised for the purposes of defence, and which entirely differ from such works as those that were placed upon the plains. The largest of these camps has been called Fort Ancient, and it must be acknowledged to be one of the most important fortified entrenchments that has ever been constructed in any part of the world. It is placed upon the summit of a hill overlooking the Little Miami river about thirty miles above its junction with the Ohio. The site that was chosen by the Indians is remarkable for its natural strength and is, upon three sides of it, almost impregnable. The hill which is about two hundred and thirty feet above the valley, is in the form of a narrow promontory having almost precipitous sides except where it is joined to the plateau. The Little Miami winds round one part of the base, and some small tributary streams join it from the other side. The shape and length of the embankments are shown in the accompanying plan, which is a reduction that I have drawn from one that was made in 1843 by Professor Locke of Cincinnati.[24] It will be observed that the ramparts follow closely the curves of the ridge of the hill and that the camp is practically divided into two parts, the outer division being near the plain, and the inner one being at the head of the promontory, where the sides of the hill are the most steep and inaccessible. The latter was probably intended as a final stronghold in the event of the outer work being captured. The magnitude of the inclosing embankments of the outer camp is astonishing. It is here that the position is most open to direct attack, and no efforts or labour have been spared in carrying out what was thought necessary to prevent capture. No Roman or British encampment that I have seen surpasses this great Indian work. I walked round the entire circuit of the ramparts. They are not less than four miles in length. They follow every curve of the hill and the heads of all the numerous ravines. [Illustration: _Fort Ancient_] The ground of the inclosure is level. At the time of my visit it was covered with forest trees, amongst which were many poplars. Upon the slopes of the embankments there was a luxuriant growth of large beeches and oaks. The quantity of earth that must have been conveyed and thrown up when forming these banks must have been enormous. The ramparts vary in height between ten and twenty feet according to the character of the natural defence afforded by the slopes of the hill. At the approach from the plain they are fifteen feet high and have a base of sixty-three feet. The platform at the top averages five feet wide.