The monuments of Petra, which we here illustrate in plates numbered Plate 22 and Plate 23, were not built by the later inhabitants, who were called Nabataeans. These monumental structures were carved out of the living rock. Some of them were temples, and others were tombs. To illustrate the extent of these works, we may note that the great open-air theatre at Petra would comfortably seat a crowd of three thousand spectators. Just a word of explanation is necessary before we proceed to the application of this discovery. Petra, the capital of Edom and the principal city of the Edomites, is found in the most rugged region of that part of the earth. The land is thrown up into abrupt ranges, which are deeply incised with canyons and gorges until they form one of the wildest and most entrancing geographical spectacles to be seen in the Eastern world. In some regions the underlying structure is limestone. The walls of the canyon, however, are largely porphyry and sandstone. The sandstone is brilliantly colored with hues which run from brown through red, to a definite purple. Some of the strata, grotesquely twisted and torn and laid bare by erosion, are among the loveliest and most entrancing geological studies in that region. In approaching the site of Petra, it is necessary to journey up a narrow canyon called in the Arabic, a siq. This approach is so narrow that almost all of the way it is scarcely possible for two horsemen to ride abreast. This might have been an important factor in deciding the site of the city in antiquity. A dozen men could have successfully defended the approaches to Petra against an entire army of invaders. Plate 24 will give some conception of the ruggedness of the country and the difficulty of approach. In place of a truck, such as would have been used in flat country, we have the familiar donkey carrying the camera and supplies. This resting place is in one of the wider sections of the canyon. Plate 25 is the first glimpse of one of the amazing monuments of Petra. This great structure bears the Arabic name of El Khazne. A full view of this temple is given in plate 26.