Final answer:
The "Hitching Post of the Sun" in Machu Picchu was used as an astronomical observatory and calendar by the Inca people.
Step-by-step explanation:
The "Hitching Post of the Sun" was a stone pillar located in Machu Picchu, an ancient Inca citadel in Peru. It is believed to have been used as an astronomical observatory and calendar by the Inca people. The position of the sun at different times of the year would cast shadows on the stone pillar, allowing the Inca to track the changing seasons and agricultural cycles.