The mural also depicted: the California Gold Rush; the 1860s building by Union Pacific of the western First Transcontinental Railroad; the disastrous 1906 San Francisco earthquake and fire; and further into the twentieth century with the city's Second World War contributions, and culminating in the 1945 signing of the United Nations Charter in the San Francisco War Memorial Opera House. Some were suspicious of Refregier as a communist because of his Russian—USSR background, and his mural topics about social issues. None of this bothered Refregier, he was only concerned about his art.