The site's history predates Ghirardelli. The Pioneer Woolen Mills occupied the block in the nineteenth century before Domingo Ghirardelli, an Italian immigrant who had come to California during the Gold Rush, acquired the property for his chocolate company. Ghirardelli had arrived in San Francisco in 1849, already an experienced confectioner who had learned his trade in South America. His company grew steadily, and the brick factory buildings that rose on the site between the 1860s and early 1900s became landmarks in their own right -- solid, handsome industrial architecture that reflected the confidence of a growing business. The complex was listed on the National Register of Historic Places in 1982 as Pioneer Woolen Mills and D. Ghirardelli Company.

When the Ghirardelli Chocolate Company moved its manufacturing operations to a larger facility in the East Bay in the 1960s, the fate of the waterfront buildings was uncertain. Demolition for apartment towers was one possibility. Instead, William Matson Roth and his mother purchased the property and hired architect Lawrence Halprin to redesign the industrial complex as a mixed-use public square -- one of the first major adaptive reuse projects in the United States. The renovation preserved the red-brick facades, the clock tower, and the industrial character of the buildings while creating a terraced pedestrian landscape with shops, galleries, and restaurants. The project opened in 1964 and proved that old industrial buildings could have economic value in their second lives.

Ghirardelli Square sits adjacent to the Aquatic Park Historic District, near Fisherman's Wharf but slightly removed from its densest tourist zones. The square is often included in the broader Fisherman's Wharf area, but its character is different -- quieter, more architectural, with views across the bay toward Alcatraz, Angel Island, and the Marin Headlands. The terraced levels of the square create outdoor spaces where visitors can sit with a Ghirardelli sundae (the company still operates a retail shop on site) and watch the cable cars climb over Russian Hill. The preservation of the factory buildings set a precedent that influenced similar projects across the country, from Boston's Faneuil Hall to the Cannery Shopping Center just down the block.