I've been to Casa Grande before, to play golf, but didn't know about the ruins after which the town is named. There was a Hohokam village here that was abandoned in the 1300's.
Father Kino first called this place Casa Grande, the great house. There are other dwellings around it, and fields, and irrigation canals that brought water from the Salt River, 27 miles away. The Hohokam traded with other communities, as evidenced by obsidian found here that originated many miles away, in multiple directions.
The residents here knew astronomy, and had windows that lined up with the sunrise on the summer solstice, and other holes in the walls that marked astronomical events.
Nobody knows why they left, or where they went.