Cusco dubbed the "navel of the universe" by the Incas, was erected by the Spanish on the ruins of Inca temples and palaces, and is as bustling with human activity now as it must have been during the empire's heyday. The city is one of South America's most popular tourist attractions, with a lively Andean culture, Inca architecture, and colonial treasures aplenty, not to mention unique access to the magnificent Machu Picchu, a must-see on any trip to Peru.