Deep within the Andes mountains of Peru lies an ancient Inca city that remained undiscovered until centuries after it was apparently abandoned.  

Here was a powerful citadel tenable against all odds, a stronghold where a mere handful of defenders could prevent a great army from taking the place by assault. Why should any one have desired to be so secure from capture as to have built a fortress in such an inaccessible place?

The builders were not in search of fields. There is so little arable land here that every square yard of earth had to be terraced in order to provide food for the inhabitants. They were not looking for comfort or convenience. Safety was their primary consideration. They were sufficiently civilized to practice intensive agriculture, sufficiently skillful to equal the best masonry the world has ever seen, sufficiently ingenious to make delicate bronzes, and sufficiently advanced in art to realize the beauty of simplicity. What could have induced such a people to select this remote fastness of the Andes, with all its disadvantages, as the site for their capital, unless they were fleeing from powerful enemies.

Although the amount of arable land which could be made available with the most careful terracing was not large enough to support a very great population, Machu Picchu offered an impregnable citadel to the chiefs and priests and their handful of followers who were obliged to flee from the rich plains near Cuzco and the broad, pleasant valley of Yucay. Only dire necessity and terror could have forced a people which had reached such a stage in engineering, architecture, and agriculture, to leave hospitable valleys and tablelands for rugged canyons. Certainly there is no part of the Andes less fitted by nature to meet the requirements of an agricultural folk, unless their chief need was a safe refuge and retreat.

In the face of tremendous natural obstacles they utilized their ancient craft to wrest a living from the soil. Hemmed in between the savages of the Amazon jungles below and their enemies on the plateau above, they must have carried on border warfare for generations. Aided by the temperate climate in which they lived, and the ability to secure a wide variety of food within a few hours' climb up or down from their towns and cities, they became a hardy, vigorous tribe which in the course of time burst its boundaries, fought its way back to the rich Cuzco Valley, overthrew the descendants of the ancient invaders and established, with Cuzco as a capital, the Empire of the Incas. As the Incas increased in power they invented various myths to account for their origin. One of these traced their ancestry to the islands of Lake Titicaca.