Last weekend, people painted buildings, streets, and T-shirts in rainbow hues for Pride parades in cities across the U.S. In San Francisco, this year marked the 40th anniversary of Harvey Milk’s becoming the first openly gay person elected to public office in California. The vibrant shades that coated avenues across the city can be traced back to Milk’s brief time as the city supervisor, when he commissioned the flag from fellow activist Gilbert Baker for the ninth annual San Francisco Pride parade in 1978 — it was, at the time, called the San Francisco Gay Freedom Day parade.

About a mile and a half from where the San Francisco Pride Parade ended last Sunday, you’ll find Castro Camera, the photo shop turned campaign headquarters where Milk rallied the people who helped bring him to office. One such individual was photographer Daniel Nicoletta, who moved to San Francisco at age 20 and got a job at Castro Camera, snapping images that would become iconic photos in the history of LGBT activism — one photograph of Milk became a Forever stamp. Nicoletta’s proximity to Milk’s life brought him back to the campaign 30 years after Milk was assassinated, when renowned director Gus Van Sant turned to Nicoletta to help him tell the story of the politician’s life on the set of the Academy Award–winning film Milk. Nicoletta was a consultant and set photographer for the film.

Since his stint at Castro Camera, Nicoletta has captured a whirlwind of images throughout 40 years of the LGBT-rights movement, from the campaign that brought Milk into office to the film that told his story. LGBT San Francisco: The Daniel Nicoletta Photographs, out today from Reel Art Press, represents the first published collection of Nicoletta’s work. The book frequently juxtaposes images of 1970s events with on-set shots from the 2008 film, showing actors reenacting the same scenes in Milk. There are panoramic shots of pride marches on Castro Street, drag performances RuPaul could only dream of, and some NSFW costumes.