The Pentagon's construction commenced with a groundbreaking ceremony in Arlington, Virginia. Architect George Bergstrom and structural engineer Sidney W. Johnson envisioned a massive, innovative design that would serve the rapidly expanding military's administrative needs. The site was chosen for its proximity to Washington, D.C., allowing for quick access to the nation's political and military leadership. The construction was motivated by the increasing pressures of World War II, as the U.S. prepared for its entry into the conflict. The building's distinctive five-sided shape was a novel approach to maximizing office space while ensuring efficient workflow and communication among military personnel.

The construction project faced challenges including labor shortages and the need for quick completion. To expedite the process, a large workforce was mobilized, and prefabricated components were utilized for efficiency. This rapid building effort led to the Pentagon being completed in just 16 months, a remarkable feat of civil engineering for the time. The building was officially dedicated in January 1943, symbolizing American preparedness and determination during a period marked by global turmoil. Its design has inspired many modern governmental and military buildings around the world, emphasizing functionality in high-pressure environments.

As the Pentagon became operational, it quickly assumed its role as the heart of military command in the United States. It housed the War Department and became a critical center for planning and coordination during World War II and subsequent conflicts. Over the years, the building expanded in both function and physical structure, adapting to the evolving needs of the U.S. armed forces. Its design allowed for future modifications and expansions, and it remains a vital icon of American military authority and resilience even to this day.