- State: AZ
- NPCA Region: Southwest
- Est. Date: 1892
Air & Climate DataView the Polluted Parks Report
The Casa Grande National Monument in Arizona features the "Great House" of the Gila Valley's ancient Hohokam people — one of the largest prehistoric structures ever built in North America. The structure’s purpose remains mysterious despite extensive archaeological excavation. Walk around the Casa Grande structure and wander the desert landscape that surrounds the site to expose yourself to the mystery of America’s ancient human history.
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