Since Machu Picchu became known to the Western world, it’s become a symbol of the unknowable past—a massive feat of construction built entirely by hand in the high mountains of Peru. Today, a UNESCO World Heritage site, Machu Picchu was designed and built in the 15th century as a royal estate for Inca emperor Pachacútec. He and his family held court for part of the year at this spectacular sanctuary where they also performed key religious rituals. The complex has about 200 structures, each with layers of cultural significance. To better understand how the Inca lived and worshipped, take a closer look at these must-see sights.