Founded in 1901, Day & Zimmermann is one of the largest private security companies in the United States. It is comprised of more than 24,000 employees in over 150 locations worldwide. The company has completed projects in nearly 75 countries. Day & Zimmermann offers architecture, engineering and construction, maintenance, modification and validation services. It provides technical protective services to the commercial, utilities, industrial and government sectors. The company also manufactures stores and demilitarizes ammunition products. It serves the Department of Defense and the Department of Energy and foreign government units. Day & Zimmermann delivers facilities maintenance services to municipal, state and federal government agencies. It additionally provides long- and short-term temporary and direct placement and managed staffing services for the information technology, scientific, engineering, health care and telecommunications communities. The company is headquartered in Philadelphia.