Enjoy San Francisco culture tourists rarely see. The venerable San Francisco Art Institute is a Spanish Colonial gem hanging off one of the city’s steepest streets. Perfumed by student acrylics, it’s a series of columned courtyards, one with a tiled fountain and in one of its free galleries a Diego Rivera masterpiece you are likely to visit all by yourself. It’s a fresco about making a fresco with Rivera’s intensely dusty colors but without Stalinist polemics.This is one of three Rivera murals in the City. The others are at SF City College and the old Pacific Stock Exchange.