Final answer:
The site and construction of Machu Picchu demonstrate the Incan expertise in ashlar masonry and their skillful integration of architecture with the surrounding rugged Andean terrain.
Step-by-step explanation:
One key factor that the site and construction of Machu Picchu demonstrates is the Inca's expert mastery of ashlar masonry, which entailed the carving and fitting of stone without the use of mortar. This technique, integral to Inca architecture, contributed to their buildings' resistance to earthquakes. Additionally, the Inca's ability to harmoniously integrate their constructions with the challenging mountainous terrain using terraced slopes is visible today amid the ruins. The preservation of Machu Picchu, undisturbed by Spanish conquest and located at an altitude of nearly 8,000 feet, showcases the sophisticated use of human labor to erect structures and walls with polished stones that fit together perfectly. Moreover, the site's designation as a UNESCO World Heritage Site in 1983 highlights the importance of its conservation due to its cultural and archaeological significance, demonstrating the Inca's advanced engineering and construction skills.