This twelve-story building was commissioned by Anson Mills on the site of his and J. F. Crosby’s four-story Grand Central Hotel (1885) that burned in 1892. The new building’s reinforced concrete frame was the fifth concrete structure designed by engineer Adolphus G. Trost after joining the Trost firm in 1908. Eight floors were completed in 1911 and four added in 1915. The Mills Building remained the tallest in El Paso until construction of the First National Bank Building (see EP17) in 1921. The building’s facades, composed of a two-story base, an eight-story shaft, and a two-story attic, are ordered by primary piers rising from ground to roof at twenty-foot intervals. Intermediate piers reinforce the verticality, while recessed spandrels and windows create a subtle horizontal balance. The cornice flares out over a curved soffit, where arches between the pilasters cut into the curve of the cornice. Aside from banner-like brackets under the sixth-floor balcony-cornice, the pier and spandrel surfaces are without ornament. The building’s curved corner and angled south elevation reflect the irregular shape of the ranch grounds and property lines predating Mills’s plat. The Trost office was located in the building until 1920. The rehabilitation by a Washington, D.C., firm was commissioned by Paul Foster of Mills Plaza Properties and founder of Western Refining.
The San Jacinto Plaza side of the 830-car Mills Plaza Garage (2010, Carl Walker) adjacent to the Mills Building at 401 N. Oregon Street is a homage to the St. Regis Hotel (1905), which formerly occupied the site.