SACRED CITIES OF THE WORLD: Machu Picchu. Scholars have no idea why the Inca Emperor Pachacuti constructed the city of Machu Pichu on a mountain top in the Andes between 1438 and 1472. It was nearly 8,000 feet in altitude, almost inaccessible, far from any populated area, and in a remote corner of the sprawling Inca Empire. Lecture by Dr. Ronald Brown. Sponsored by the Friends of the Library. 3 p.m.