@Widowmaker
Thanks for the suggestion. I checked out the sign at the Myrtle trail head. Unfortunately, it didn't have any information about the one room stone building South of 1A and West of Piestewa Peak.

The write-up on Perl Charles #1A in the Phoenix Mountain Preserve refers to a CCC stone structure. The Park Rangers believe this was a structure built for a mine in the area. For me it has all the characteristics of a CCC construction. What is the real history? Why and when was it built ?