Day & Zimmermann Design Listed as Significant Historic Place in Philadelphia

PHILADELPHIA, PA – December 14, 2021 – Fox Motor Car Company, a property constructed by Day & Zimmermann in 1921, has been listed as a significant historic place by the Philadelphia Historical Commission. Located at 721 West Grange Avenue, it was constructed as a manufacturing site for air-cooled luxury automobiles. Day & Zimmermann (D&Z) is proud to be recognized for their design, exactly one century later.

Founded by Ansley H. Fox, the Fox Motor Car Company positioned itself as an ultra-modern company that used cutting-edge technology to manufacture a revolutionary product. Instead of contradicting that image by occupying an existing building, Fox engaged the Philadelphia engineering firm of Day & Zimmermann to design and build a new one. Fox promotional materials would later describe this factory as “one of the most up-to-date plants in the country,” and “one of the most modern automobile factories in the world.”

Day & Zimmermann fully embraced modern technology in their design of the FMCC building. Walls are modular, glass accounts for a large majority of the wall surface and window frames are of metal, providing fire-resistance while minimizing light obstruction. The three story structure is narrow and rectangular, comprised of brick, concrete and glass. The building borders the Fern Rock Transportation center in North Philadelphia.

The factory embodies distinguishing characteristics of an architectural style or engineering specimen, C.A.P. Turner’s flat-slab, or, as it was better known, the “mushroom system” factory building. This had become the modern standard by 1910. Day & Zimmermann’s design exemplifies this system, which combined poured concrete with steel reinforcement to produce well-lit, fireproof buildings with abundant floor space.

Today, the building no longer stands as an automobile factory, but as a light industrial company with a 30 year history. Designed by D&Z, the building exemplifies the changing industrial character of the city during the 20th century. It has value as part of the heritage of the city as a rare (and possibly the only) surviving automotive manufacturing plant in Philadelphia, and it remains as an important reminder of that aspect of Philadelphia’s history.


Founded in 1901, Day & Zimmermann is a family-owned company with a workforce of over 41,000 specializing in construction & engineering, staffing and defense solutions for leading corporations and governments around the world. Operating from more than 150 worldwide locations with 2.4 Billion USD in revenue, Day & Zimmermann is currently ranked as one of the largest private companies in the U.S. by Forbes. Headquartered in Philadelphia, PA, our first work was to develop "Betterment Reports" that helped modernize American factories. Today, we are still in the business of betterment—maintaining the nation's power infrastructure, protecting American freedoms and driving technological advancements around the world. We do what we say®


  • ,