The Armour Building is a three-story brick building in the city's waterfront warehouse district. Its main entrance is on Battery Street; it also has a facade on Union Street. It was designed by Henry Geilfuss &amp; Son, a prominent San Francisco architectural firm of the period, as a meat smoking and packing facility, and was built in 1907 in an Italianate style. The site was previously occupied by a 1902 American Milling Company warehouse, also designed by Geilfuss, which was destroyed in the 1906 earthquake and fire.