The wall is not of regular shape. It runs around on the very brow of the hill, except in one or two places, where it cuts across a ridge. In 1843 this wall was still about five feet high and thirty-five feet base. The earth and stone of which the wall is made were evidently gathered up from the surface of the hill. In some places holes had been excavated, probably for the double purpose of securing materials for the wall, and providing reservoirs for water against a time of need. There are but four openings in the wall, and each is very carefully guarded. The complicated walls guarding the main entrance to the north are especially noticeable. There are no less than four inner walls besides the crescent shaped embankment on the outside. The signal mound was about five hundred feet to the north of the main opening. The stones on the surface of the mound all show the action of fire. If we were uncertain of the uses of the other class of inclosures, which have been named Sacred Inclosures, we have no need to hesitate as to the character of this work. Every thing in reference to it betokens that it was a defensive work. The valley of the Big Miami, in which it occurs, was a favorite resort of the Mound Builders. On the opposite side of the river, to the south, was a square and an ellipse combined, and several other large works were ranged along the river in the course of a few miles. We need scarcely doubt that this was a citadel in times of need, and that when warning columns of smoke or flaming fires showed the approach of an enemy, the old and the sick, the women and the children, fled hither for protection, while the warriors went forth to battle for their homes.