This wonderful postcard presents a bundle of unanswered questions. It depicts George Fred Keck's 1933 House of Tomorrow at the Century of Progress International Exposition (or world's fair) in Chicago.
In The Solar House I discuss this building in great depth as the site where Keck "discovered" passive solar heating, and subsequently began a decade-long journey to develop the solar house. (I also note that Keck probably turned a blind eye to the house's summer overheating problems when he later constructed the solar house legend.)
The mystery is, who painted this watercolor? This image shows excellent technique, and Fred Keck was a quite accomplished watercolorist himself. You can find one example of Keck's fine brushwork---the Coronet house---in my book. Keck's archive at the Wisconsin Historical Society in Madison has dozens of watercolors, mostly abstracts but some architectural illustrations.
I do not believe Keck created this painting. The postcard does not credit the artist explicitly, although a faint maker's mark can be detected in the lower right just beneath the automobile (a Pierce Arrow?). The name seems to read Heiling, or Helling. I think the most likely explanation is that the artist was an in-house employee of Reuben H. Donnelley, working from Keck's drawings or a picture of a model.
Another mystery is why the penthouse-level is shown with the exterior skin of glass set deeply beneath an overhanging roof slab. In the completed house (see here), the upper glass wall is located at the outer edge of the roof slab. Is it possible that Keck's original design intended to have the glass in the location shown here? (I did not find any archival documents showing this configuration, but I'm not sure I have been able to find everything in Keck's archive.)
In any case, it's a striking image of a vision of the future, rendering the glass house as crystalline and reiterating a theme which was central to early modern architecture.