Archeologists do not know for sure why the Casa Grande was built, and its original purpose remains a puzzle with more questions than answers. Its walls line up north-south-east-west for unknown reasons, and the sun and moon can still be observed lining up with certain holes in the wall year after year. It may have been an astronomical observatory, a place for sacred ceremonies, a workplace for a leader who oversaw important irrigation canals, or a home for an influential family or clan. The Casa Grande likely served many purposes and functions for the Ancestral Sonoran Desert People who built this impressive multi-story building about 700 years ago.