The ancient Incan sanctuary of Machu Picchu is considered one of humanity’s greatest architectural achievements. Built in a remote Andean setting atop a narrow ridge high above a precipitous river canyon, the site is renowned for its perfect integration with the spectacular landscape. But the sanctuary’s location has long puzzled scientists: Why did the Incas build their masterpiece in such an inaccessible place? Research from the Geological Society of America now suggests that the Incas intentionally built Machu Picchu and some of their cities in locations where tectonic faults meet; and it would be impossible to build such a site in the high mountains if the substrate was not fractured. Says researcher Rualdo Menegat, “The faults and fractures underlying Machu Picchu helped drain the site during the intense rainstorms prevalent in the region. The pre-existing fractures aided this process and help account for its remarkable preservation. Machu Picchu shows us that the Incan civilization was an empire of fractured rocks.”