At Mount Joliet, near the town of Juliet, on the Illinois river, is probably the largest mound within the limits of the United States. It is raised on a horizontal limestone stratum of the secondary formation, and is sixty feet high; and measures, at the summit, eighty-four rods in length and fourteen in width; and, at the base, it is much larger. In the neighborhood of Rock river (Illinois) the mounds are numerous, and give evidence that there once existed in that vicinity a dense population. Southeast of the city of Cuernavaca, on the west declivity of Anahuac, there is an isolated hill, upon the top of which is a pyramid. The whole height is upwards of six hundred feet, and it is five times as large as the tower of Babel. It has five terraces, each of nearly sixty feet in height, covered with solid masonry, upon the top of which rest the artificial works; and the whole is surrounded with a broad deep ditch. In Peru, on the Cordilleras, at a surprising height, are works still more considerable. From a general resemblance of these structures throughout the whole American continent in their apparent purpose, age, and style of architecture, it is generally presumed that the architects belonged to the same races of native Indians. I say races, for there are reasons for believing that the American continent has witnessed the growth and extinction of more than one race of men which had advanced to a high state of civilization. Wirt’s impressions are, that three distinct races of men have occupied this country previous to the arrival of the existing white settlers. The monuments of the first or primitive race are regular stone walls, brick hearths, (found in digging the Louisville canal,) medals of copper, silver swords, and implements of iron. These relics, he thinks, belonged to a race of civilized men who must have disappeared many centuries ago. To them he attributes the hieroglyphic characters found on the limestone bluffs; the remains of cities and fortifications of Florida; the regular banks of ancient live oaks near them; and the hard and regular bricks found at Louisville, that were longer in proportion to the width than those of the present day.