Toltec and mentioned in Mexican myth as the scene of the rising of the historical sun. At the present day this site presents the appearance of a conglomeration of mounds varying greatly in size and spread over so large an area that their bulk is difficult to realize. The two principal features are two vast pyramids, from the smaller of which runs a depressed road, two to three hundred feet wide, past the other for a distance of nearly two miles in a straight line. This road is interrupted by several low embankments and small pyramids, and bordered by a large number of mounds arranged in series. At the southern end of the road and to the east is a complex of mounds, arranged in a square and including a pyramid of some size. The photograph figured on Pl. XII is taken from the summit of the lesser of the two great pyramids, usually called the “pyramid of the moon,” and looks down the sunk roadway, called the “road of the dead.” The greater pyramid, or “pyramid of the sun,” appears in the centre of the picture, but the complex of mounds towards the southern end of the road is barely visible. The “pyramid of the sun” measures about 700 feet along the base, and the sides rise at an angle of 45 degrees to a platform about 100 feet square. Both it and the surrounding mounds are composed of masses of local earth and stone and adobe (unbaked clay). It was originally faced with roughly dressed stone and received a final coat of stucco. Beneath the outer facing a second has been discovered at some depth, and it may be that several such were constructed during the process of building in order to give solidity to the mass; but it is more likely that the outer layer represents an addition to the original building. Other evidence of phases in construction have been discovered in some of the mounds, in cases where an entire building has been filled solid in order to support a later edifice above it. Growth by accretion of this nature was a feature of many of the Maya sites, as will be seen later. It is probable that this mighty pyramid was approached by a stairway on its western face from the “path of the dead.” The general assemblage of the lesser mounds seems to exhibit more evidence of design than many Mexican ruins, and the whole site bears the stamp of considerable antiquity as well as long-continued occupation. In particular is to be noticed a tendency to group the mounds round quadrangular courts, a tendency which, as will be seen later, is characteristic of the Zapotec area. The district from early times bore the reputation of a burial-ground of great sanctity, and the lesser mounds were at first believed to be burial-tumuli (whence the name “path of the dead” given to the sunk roadway). Excavation however, as far as carried out, seems to prove that the greater number supported buildings of a residential nature, many of them of an unusually complex ground-plan. The walls were of lava fragments and adobe, dressed with mortar.