Machu Picchu is a masterpiece of Incan civil engineering and architecture. It took much skill to build it up high in the mountains and make it stay together for this many years. It is very pleasing to the eye; as Ruth Wright puts it, "Even the buildings of Machu Picchu were in harmony with the mountain backdrop." (caption before 15) Some of the many other elements that make it stand out are the simple construction tools used, the excellent stonework, the ingenious water supply, and the splendid Temples of the Sun, the Condor, and the Three Windows.
Mears, Jonah S., "Machu Picchu from an Engineer's Perspective" (2019). Scholars Day. 46.