So now, when I put THESE two images together for the first time, I find a discrepancy that makes me question the source's caption. The Krenkel color illustration below is captioned in Illustration Magazine as The Baths of Khandahar. Whereas the grey-tone study is labeled in Krenkel's writing as a study for Zenobia. Khandahar is an ancient city of Afghanistan, and Zenobia was a 3rd century queen of Palmyra, which is present day Syria.
I suppose Illustration Magazine is accurate with the caption, but now I don't trust anyone's info . . . except for Mr. Door Tree.
In any event, once again, pure Krenkel gold: