Final answer:
Option (3), The Observatory at Machu Picchu served multiple purposes: a sacred place for astronomical observation, temple worship, and performing solstice rituals, reflecting the Incans' advanced understanding of celestial phenomena and its integration into their culture.
Step-by-step explanation:
The Observatory, City of Machu Picchu, functioned as a sacred space used to chart the sun's movement, a temple dedicated to the sun god, and a place for ritual and astronomical observation. The location of the Temple of the Sun at Machu Picchu was chosen specifically to align with celestial events like the winter and summer solstices, allowing for precise observations that were critical to Incan society for agricultural and ceremonial purposes. Astronomical observations were intertwined with religious beliefs, reflected in the alignment of buildings and the careful placement of windows to track the sun's path on important dates.
The Incans exhibited a profound interest in and understanding of celestial movements, integrating these into their architecture and religious practices. They conducted rituals and sacrifices within the Temple of the Sun, particularly during the solstices. In addition to being a religious center, the city of Machu Picchu served as a royal retreat and remained untouched by the Spanish due to its remote location.
This combination of spirituality, astronomy, and exacting stonework craftsmanship without the use of mortar (ashlar masonry) underscores the importance of the Observatory within Incan society. The harmonization of their calendar system, agricultural cycles, and ritual ceremonies with the celestial events demonstrates a sophisticated understanding and reverence for the sky above.