Another stronghold of considerable importance may be seen at Fort Hill, in Highland county, on an elevation of 500 feet, and enclosing an area of forty acres.  There is another near Piqua, on a hill 160 feet high; and another near the city of Dayton, on a hill 160 feet high, where a mound is enclosed, which like the ancient watch-towers of Scripture, can command a view of the whole surrounding country.  Near Carlisle lies the site of another remarkable military enclosure, which overlooks the fertile valley, between the Twin and Miami Rivers.  Two deep ravines fortify the north and south sides, while an almost perpendicular bluff fortifies the east.  The wall which is partly of earth and partly of stone is 3,676 feet in length, and encloses a beautiful area of fifteen acres.

The settlers state that in early times there were two stone mounds and one stone circle, which contained such excellent building stone, that they removed them for building purposes.  They had to cut a way and grade it, to remove the stones, which those rude architects of early prehistoric times found no difficulty in taking from a distant quarry to that high elevation.  We must therefore agree that their knowledge of the mechanical powers was far superior to anything the Indian race has shown.

About the largest fortification in Ohio may be seen at Bournville.  It encloses a magnificent area of fertility, on an elevation of 400 feet.  The sides are remarkably steep, and are washed by small creeks, that empty into Paint Creek hard by.  Within the fortification are several depressions, where water remains most of the year.  The area, of itself, would be a beautiful farm, as it consists of 140 acres.  The wall, which was about 2-1/4 miles in length, is very much in ruins, being chiefly built of stone.  Some years ago the whole place was covered by the trees, and on the dilapidated stone wall, may still be seen immense trees, whose growth among the stones helped to displace them.  The decayed wood beneath some of these trees indicates that successions of forests have flourished since these forts were abandoned by those who made them.

Graded ways.—­It is well known that, in most of these valleys; there are several terraces, from the river bottom or flats, up to the high lands in the distance.  Near a place called Piketown there is a beautiful graded avenue.  The third terrace is seventeen feet above the second and the second about fourteen feet from the river flat.  These terraces form, when graded, this avenue, which has walls on either side in height twenty-two feet.  These walls run for 1,010 feet to the third terrace, where they continue to run for 2,580 feet, terminating in a group of mounds one of which is thirty feet high.  Some distance from these walls another wall runs 212 feet at right angles, and then turns parallel for 420 feet, when it curves inwardly for 240 feet.