At first I thought of fraternal organizations, since some of them appropriate Egyptian motifs. But even the Shriners don't have conventions lasting three weeks! Both the sphinx and the pyramid shape look Egyptian -- not Aztec, Mayan, or Toltec -- to me. I can see why you're skeptical of the claim to a connection with the Columbian Exposition, both for that reason and because the dates precede the Exposition. Gee, thanks, Bill. Now this is going to bug me.