But our monuments do not merely consist in such mounds or tumuli, since we find besides in North America, ruins of cities, some of which were walled with earth or even stones, real forts or citadels, temples and altars of all shapes, but chiefly circular, square or polygonal, some elliptical, hexagonal, octagonal, _&_c., quite regularly pointing to the cardinal points. We have also traces of buildings, foundations, roads, avenues, causeways, canals, bridges, dromes, or racecourses, pillars and pyramids, wells, pits, arenas, _&_c. And of these not a few, but hundreds of them, many of which are unsurveyed and undescribed as yet. These, it must be recollected, are all north of Mexico, or the region of the more perfect monuments of Mexican and Central America, although often in the same style. There, as in South America, structures are met of the most elaborate workmanship, of cut and carved stones, with hard cement, vaulted arches, fine sculptures and even inscriptions. The materials of our Northern monuments are often ruder, chiefly of earth, clay, gravel, small stones, or even _shells_ near the sea-shores, sometimes of _pize_ or beaten and rammed clay, (as in Peru,) unbaked bricks and rough stones. These facts may confirm the Mexican traditions, stating that the nations of Anahuac (now Mexico) once dwelt further north, in our fruitful Western plains, where wood abounded and stones were scarce, wherefore they built their cities and _t_emples[TN-5] of wood, raising altars, platforms, walls and entrenchments of earth or clay. The dreams and false hypotheses upon America have amused the learned for ages: in attempting to account for the origin of the Americans and their monuments, they have generally neglected to compare them with the monuments and languages of all the other nations scattered over the whole earth, or else only taking a partial view of them, comparing a few fragments of two or three nations or regions, a few words of a centesimal part of the actual languages, the writers or historians have fallen into egregious mistakes; more fond of systematic errors than hidden truth, they have indulged, without due consideration, in mere dreams or systems, based on a few facts, that are overruled by hundreds of other facts, unknown to them, or neglected when known. It would be useless and tedious to refute again such false systems, that have been refuted and upset by each other. It may, however, be needful, perhaps, to mention three of the most absurd, in order to warn against them, or show their improbability and impossibility. They may be called for distinction sake, the _Jewish_ system, the _Mongolic_ system, and the _American_ system.