See's Factory

Another staple of my childhood was being located not far from the See's Candies factory headquarters in South San Francisco on El Camino Real and was able to see and visit it often. The fruit flavored truffles are by far and away my favorite of their products, and the lemon, key lime, and apple pie flavors are among my favorites.

The El Camino Real location. All pics from the wiki article. 

As for a little history, the company itself was founded by Charles See, his wife Florence, and his widowed mother Mary after emigrating from Canada in 1921, and was initially headquartered in Los Angeles, California. Mary in particular was the secret to the candy itself, with all the original candies being her own recipes that she developed when living in Canada. The first shop was located at 135 North Western Avenue in Los Angeles, and the store's iconic black and white porcelain look was first introduced in 1941.

The specific store in South San Francisco was opened in 1936 during the height of the great depression (which See's did surprisingly well in) and they quickly moved their creams and truffles production (60% of their product) to this facility to specifically take advantage of the often cold local weather. 

The couverture chocolate used by See's in their product is actually sourced from the nearby Guittard Chocolate Company. The nuts used in their candies are also locally sourced from the Mariani Nut Company of Winters, California.   

A shop location in Hong Kong.

In 1972 the See's family sold the company and it is now owned by Berkshire Hathaway, who have greatly expanded the company's marketing and product availability outside of California. But, they still rely on their headquarters in South San Francisco for a majority of their production, and you can still visit it today.