New research shows that Machu Picchu, an ancient Incan citadel set high in the Andes Mountains in Peru, was occupied from about 1420 to 1532 CE, with activity beginning two decades earlier than suggested by the textual sources. Machu Picchu, the famous 15th-century Inca site near Cusco, in southern Peru. Image credit: Oleg Dyachenko. Machu Picchu, located about 80 km (50 miles) from Cusco, Peru, is one of the most famous archaeological sites in South...
