Casa Grande Ruins National Monument

Casa Grande Ruins National Monument

Yesterday we visited the Casa Grande Ruins National Monument near Coolidge, Arizona. We learned that in 1694 the Jesuit missionary Eusebio Francisco Kino (1645-1711) was the first European to see this distinctive building. He named it “Casa Grande,” Spanish for “Great House.” It is four stories high and 60 feet long, the largest known structure of the Ancestral Sonoran Desert People, the current preferred name rather than the previously used term “Hohokam.” These people built irrigation canals to support growing a variety of agricultural crops. They were active starting about 300 BCE and continuing until around 1400. Casa Grande was probably built around 1350. On October 31, 1775 Juan Bautista de Anza described the ruin in his journal while camped along the Gila River. He and his party of colonists traveled all the way to the Presidio in Monterey, California where they arrived on March 10, 1776. There is speculation surrounding the purpose of Casa Grande. For me, the evidence of their astronomical interest is most telling. At sunset on the summer solstice, the longest day, there is a small hole where sunlight becomes visible on a wall. Other holes similarly display the vernal equinox in March and the autumnal equinox in September. Additionally, there is a hole where the moon “stands still” in the sky every 18.6 years. Remarkable. Another interesting highlight of the trip was seeing the oval indentation identified as one of some 200 ball courts in Arizona. The Visitor Center film, “Casa Grande: Home of Many Stories,” was a good introduction to this, the country’s first archeological reserve established in 1892.

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