Hidden inside San Francisco's Stock Exchange tower is a priceless treasure: Diego Rivera's 1930–31 Allegory of California fresco. Spanning a two-story stairwell between the 10th and 11th floors, the fresco shows California as a giant golden goddess offering farm-fresh produce, while gold miners toil beneath her and oil refineries loom on the horizon. Rivera's Allegory is glorious, but cautionary – while Californian workers, inventors and dreamers go about their business, the pressure gauge in the left-hand corner is entering the red zone.
Today it seems strange that architect Timothy Pflueger would invite such an outspoken critic of capitalism as Diego Rivera to paint the mural gracing San Francisco's Stock Exchange Lunch Club (now the City Club) – but after the 1929 US stock-market crash, Rivera wasn't the only skeptic of unregulated markets. The Allegory of California was his first US fresco commission, and it would be a couple of years before his Rockefeller Center mural in New York was denounced as communist and scrapped. Instead, Rivera and his young bride – the groundbreaking surrealist artist Frida Kahlo – were the toast of San Francisco, and started a mural movement that continues here today.