On the second floor of a nondescript building sits one of San Francisco’s best secrets—the Prelinger Library, an idiosyncratic collection of image-rich historical ephemera, periodicals, maps, and books from the 19th-century to present. Opened in 2004 by Megan and Rick Prelinger, the library has no card catalog or Dewey Decimal Classifications. Instead, the stacks are arranged more like a stream of consciousness. Wanting library research to be as fun as a field trip, the ’zinester-turned-historians organized the collection as if it were a landscape for visitors to explore. The shelves begin in the Western US and end in outer space. In between, you can flip through 50 years of TV Guide magazines, old concert flyers, school textbooks from 1880-1970, and periodicals with titles like “Social Hygiene” and “Candy Manufacturers and Confectioners Journal.” Stop by on a Wednesday afternoon (they have occasional Friday/Saturday hours, too) and get lost in the library’s 30,000 bound objects, 60,000 loose sheets, and 10,000 zines.