Fiction, Young Adult Novel, about a friendship between two boys and their adventures in searching for and finding a pottery jar which contains a "treasure": ancient quipu [knotted cord] records that hold the history of the Inca Empire. One boy is son of American mining engineer, working in Peru, near the ancient city of Macchu Picchu [from which is derived the title of the book]. The other boy is Peruvian, whose grandfather challenges the boys to recover the lost treasure. The subplot is of the engineer, unknowingly being "used" by unscrupulous Peruvian adults, as he seeks for a vein of gold. Due to the friendship between the boys and their success in finding the quipus, the grandfather tells the engineer the ancient Inca secrets of finding and extracting the gold. The unforgetable motto --- "Go aside and pray for innocence and honor" --- struck me when I first read this book as a teenager in the late 1940s. The book is based on archeological research of Macchu Picchu by Hiram Bingham and his team, sponsored by "National Geographic" magazine --- see the issue for April 1912 (or thereabouts). [signed: billy jack]