Day & Zimmermann Recognized in Engineering News-Record's List of Top Design Firms

PHILADELPHIA, PA – May28, 2020 – Day & Zimmermann, the century-old, family-owned provider of construction & engineering, staffing, and defense solutions for leading corporations and governments around the world, has been ranked by Engineering News-Record (ENR) in its 2020 list of the top 500 design firms. Day & Zimmermann has also been named by ENR as one of the top 50 international firms of 2020.

“Day & Zimmermann’s recognition as an industry leader is a testament to our decades-long commitment to the corporations and governments we serve,” said Michael McMahon, President of Day & Zimmermann’s Engineering, Construction and Maintenance group. “Even in the face of challenges brought on by COVID-19, we are responding across our businesses and in particular on the 10 years of market growth the design firm industry has experienced. We’re focused on finishing strong in 2020 by continuing to provide the innovative and transformative solutions our customers have come to expect and rely upon.”

“As a Day & Zimmermann Company, Mason & Hanger is proud to rank among the top A/E industry leaders,” said Benjamin Lilly, President of Mason & Hanger. “We are committed to Building a More Secure World and are proud of our long-term support for the U.S. National Security mission by providing critical architecture and engineering services to the U.S. Government.”

ENR compiled its rankings based on the revenue each firm received for design services provided in 2019.



Founded in 1901, Day & Zimmermann is a family-owned company with a workforce of 41,000 specializing in construction & engineering, operations & maintenance, staffing, security 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 accelerating innovation around the world. We do what we say.® For more information, visit


Mason & Hanger, a Day & Zimmermann Company, is dedicated to providing architectural and engineering services, specializing in the worldwide design of secure, mission-driven facilities, proudly serving as a partner to the United States Government for nearly two centuries. As one of the longest operating A/E firms in the United States, Mason & Hanger has a rich history covering nearly 200 years. With a mission of Building a More Secure World, the Company has served the federal government on thousands of projects, in 48 states and 165 countries. Mason & Hanger is a top 250 ENR design firm and is ranked #3 for federal and #4 for military revenues among engineering firms by Building Design + Construction. For more information, visit