The very extensive mounds and remains which constitute Teotihuacan are of numerous pyramids, and some ruined walls which have been excavated of recent years. All of these are formed of _adobe_ and irregular pieces of the lava of which the adjoining hills are composed. Rude carved monoliths of deities have, however, been recovered from the _debris_. The main features of the ruins are, first, the "Pyramid of the Sun," a huge mound which forms the most colossal structure of prehistoric man in America. It measures, approximately, at its base--for its outlines are so indefined that no exact form can be adduced--some 700 feet on each side, rising upwards in the form of a truncated pyramid rather less than 200 feet above the level of the plain. Next, the "Pyramid of the Moon," a similar but smaller structure--about 500 feet at base--distant from the first some thousands of yards along a strange road or path across the plain, known as _Micoatl_, or the "Path of the Dead," some two miles in length. From the summit of the "Pyramid of the Moon" the beholder looks down into the great courtyard of an adjoining group of ruins; thence his eye travels along this pathway to where the huge "Pyramid of the Sun" arises, far off, on its left-hand side. Between these and indeed beyond them, and bordering on the "Path of the Dead"--probably so called in relation to human sacrifice--are numerous other mounds, which were formerly pyramids of similar character, but of much less magnitude. Probably, in ages past, they were all crowned by temples, and ascended by staircases and terraces--evidences of which, indeed, still remain--whilst the slopes were probably covered with stone and stucco. It is stated that upon the high summit of the great pyramid--that dedicated to Tonatiuh, the sun--a huge stone statue of this deity was placed, and that a plate of polished gold upon its front reflected back the first rays of the rising sun. The name Teotihuacan signifies the "house of the gods." Doubtless it was, in unknown centuries past, the centre of a thriving civilisation and busy and extensive agricultural population. To-day the great pyramid casts its shadow toward a small village of _jacales_, upon a semi-arid plain.