I love these murals as they perfectly depict the Bay Area. They are some of my favorite works of art, although for legal reasons (I believe) they are not available for purchase as posters or anything else.
San Francisco is fraught with murals from the 30s.
In 1931 Diego Rivera completed one of my other favorites, and one of his best: The Making of a Frescoe Showing the Building of a City. I've enjoyed this mural since I was a kid. And yes, that is Diego's paunchy posterior front and center. The look of resignation on the workers face is an excellent tribute to the labor movement of the era. It is also a marvelous example of trompe l'oeil blending into the room of the San Francisco Art Institute.
Speaking of Diego Rivera... In Coit Tower a number of publicly financed artists, as part of the New Deal's WPA program, reacted against the destruction of Diego Rivera's Rockefeller Center mural Man at the Crossroads (notably dramatized in the film Cradle Will Rock). In their frescoes they depict a number of explicit socialist themes.
The WPA also commissioned a series of murals in 1936 at the far end of Golden Gate Park, in the Beach Chalet. These murals, which are very pastoral, were painted by Lucien Labuadt. While less explicit, one should note the prominent inclusion in one panel of labor leader Henry Bridges.
Pushing the cart
The Rincon murals were far more controversial than even Coit Tower. Painted by a Russian immigrant, Anton Refregier (who had started as part of the WPA) they depict bitter memories and class struggles - painted when the burgeoning Cold War was not sympathetic to such depictions. Even Nixon tried to have them covered. But, then again, if Nixon doesn't like it, that probably means that it's a good thing.
The Rincon series is called The History of California and shortly after its completion another set of murals, by Jan Henryk de Rosen, also depicts the history of the area, this set in the aisles of Grace Cathedral. Originally painted between 1949-50, these murals have explicitly no political tone, albeit depicting the UN charter, and unlike Refregier's highly cubist works, the art deco and cubist influences are almost gone.
These bring us full circle, in a way, to the original Piazzoni murals. You can tackle California in many ways. You could, like the muralists of the 40s, depict the history of the area with images of the Great Fire, the Bear Republic, and Sir Francs Drake. You could, like the muralists of the 30s, show the political and social conditions - the important people who shaped the land. The tensions and shared culture. But I prefer Piazzoni. He captures, in two landscapes, the reality of California without politics, social commentary, or history, yet profoundly distilling what this place actually is.