[Illustration: FIG. 34.--Plan of a court and buildings at Mitla. The building to the right is shown on Pl. XV.] [Illustration: _PLATE XV_ _Photo. C. B. Waite_ ZAPOTEC RUINS AT MITLA, OAXACA; PARTLY RESTORED] To return to Oaxaca, the most important group of ruins awaits consideration. These are at Mitla, the sacred Zapotec city, and are distinguished by many peculiarities which render them almost unique. Here the quadrangular arrangement of buildings round courts attains its most definite form. In two cases one of these buildings, on the east side, is a pyramid, and therefore presumably approached, as usual, from the west. The rest consist of long low buildings upon terraces, opening as a rule only upon the court which they surround, though in two cases one such building gives access at the back to another court, entirely enclosed by similar buildings, which has no other entrance (Fig. 34). The material is rubble, faced with trachyte blocks set in mortar; the wall-surfaces are broken by sunk panels filled with the mosaic geometrical ornament which gives this site a character of its own (Pls. XIV, 1, and XV). Each block constituting the mosaic bears on its face in relief some detail entering into the design, but the blocks are not uniform, and each therefore was cut and fitted to its particular place, a method entailing enormous labour, especially when it is realized that over eighty thousand were employed in the ornamentation of one quadrangle alone. The blocks taper somewhat at the back, so that they were set in the mortar as a tooth in the gum, a feature seen also in Maya buildings. The designs are obviously based on the textile art, and find their closest parallel in some of the coastal buildings of Peru (though similar mosaics have been found at Tlacolula, also in Zapotec territory). Stucco was not used here for moulded ornament, though it was employed for finishing defective points in the facing. Traces of red colour are found on the mosaic panels. The durable yet comparatively soft trachyte found in the neighbouring hills afforded the Zapotec builder far more tractable material than at other sites; the result was that large masses of stone were used in construction, such as lintels from ten to twenty feet long and weighing from ten to fifteen tons, as well as cylindrical pillars used to support the roof in the broader buildings. Indications show that the roof consisted of logs, probably covered with canes supporting a layer of masonry and cement. The quarries of the ancient builders have been discovered in the hills, together with the rude stone picks by means of which they hewed out the blocks, and, as Holmes writes, “the feats of engineering necessary to transport masses of stone many tons in weight down a thousand feet of precipitous mountain-face, accomplished by these stone-age quarry-men, would be regarded as important undertakings, even by our enterprising engineers of to-day.” It is an interesting fact