The fineness of the stonework is, of course, the most remarkable characteristic of the Incas’ architecture. They seemed able to fit, with equal facility, blocks of stone weighing tons and those weighing but a few pounds. Although they are not known to have used the T-square, some of their angles are very true, and when it seemed desirable, they could build a straight wall. Particularly beautiful are some of their circular structures, such as the Temple of the Sun in Cuzco. It is probable that only the temples and palaces of the rulers were so well built, and that the common people lived in houses of mud and stone. One of the most remarkable structures in Peru, the temple of Uiraccocha (u-eer-äk-ko´-chä) at Racche (räk´-chay), shows a combination of fine stonework, and mud and stone. In addition, the upper part of these walls, which tower some thirty feet high, is of _adobe_ (a-do´-bay) only, and centuries of weathering has done but little more damage to the sun-dried bricks than to the granite foundations. There is something incongruous in the fact that the roofs of the buildings walled so beautifully, and often covered inside with skilfully woven tapestries and gold adornments, were commonly of thatch. The rafters were of wood, tied on to ring stones and projecting cylinder stones with maguey withes. But, although they were ignorant of iron, did not even mortise their timbers, and were content with a dingy, unlighted interior, the buildings of the Incas were adapted to the character of the climate, and the wisdom of their plan is attested by the number which still survive, while the more modern constructions of the conquerors have been buried in ruins. Providing they escape the destructive hands of the treasure-hunting Peruvians, only a gigantic cataclysm of the earth’s surface can destroy these monuments to the stoneworking skill of Peru’s ancient inhabitants. PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION ILLUSTRATION FOR THE MENTOR, VOL. 6, No 3, SERIAL No. 151 COPYRIGHT, 1918, BY THE MENTOR ASSOCIATION, INC. [Illustration: DOORWAYS IN INCA RUINS OF ROSASPATA] _THE INCAS_ _Vitcos and Tampu-tocco_ SIX The location of Vitcos (veet´-kos), or Pitcos (peet´-kos), the home of the Inca Manco after he fled from Cuzco to the wilds of Vilcabamba (veel-kä-bäm´-bä), was one of the questions which students of Inca history had never answered. Arm-chair archeologists and historians had selected the site of Choqquequirau (chok-kā-kee-rä´-oo) (cradle of gold), which consists of a series of extensive ruins above the Apurimac (a-poo-ree´-mak) River near Abancay (ä-bän-ca´-ee). His visit to these ruins convinced Dr. Hiram Bingham, of Yale University (now Lieut.-Colonel Bingham), that Vitcos and Choqquequirau could not be identical.