Casa Grande Ruins National Monument - http://www.nps.gov/cagr

For over a thousand years, prehistoric farmers inhabited much of the present-day state of Arizona. When the first Europeans arrived, all that remained of this ancient culture were the ruins of villages, irrigation canals and various artifacts. Among these ruins is the Casa Grande, or "Big House," one of the largest and most mysterious prehistoric structures ever built in North America. Casa Grande Ruins, the nation's first archeological preserve, protects the Casa Grande and other archeological sites within its boundaries. You are invited to see the Casa Grande and to hear the story of the ancient ones the Akimel O'otham call the Hohokam, "those who are gone."