Machu Picchu, meaning 'old peak', is an ancient Inca citadel in Peru and a UNESCO World Heritage site, renowned for its impressive architecture and historical significance as a last vestige of the Inca Empire. The site includes over 150 buildings, advanced masonry, and earthquake-proof structures, and it was never discovered by Spanish invaders, remaining hidden until its rediscovery by Hiram Bingham in 1911. Visitors can explore the complex via various hiking trails or train routes, learning about its rich history and engineering marvels.