Perched atop 5681-foot Harquahala Mountain in west-central Arizona are the remains of the Harquahala Peak Smithsonian Observatory. This observatory was used from 1920 to 1925 to make scientific measurements of the sun's output in an attempt to predict the weather. The main observatory building, an adobe structure with metal siding, now stands empty behind a protective fence.
At the time of my visit (November 1997) the dirt road to the observatory was rough but passable to a 4-Wheel-Drive vehicle, however its condition varies and it may at times be impassable. The side road to Ellison's Ranch was severely washed out, so I hiked down to those ruins. I understand the mountaintop has since been improved with the addition of parking areas and picnic tables.
A fascinating look at the history of the observatory and ranch can be found in Pieter Burggraaf's book Harqua Hala Letters, which was published in 1996 by the Bureau of Land Management but is unfortunately now out of print.
January 12, 2001: J. Keller informs me that Harqua Hala Letters is back in print and copies can be purchased from the BLM.