The Pentagon, the world's largest office building at the time, was completed in Arlington, Virginia after just 16 months of construction, serving as the headquarters for the U.S. Department of Defense.
The Pentagon stands as one of America's most iconic government buildings and serves as the headquarters for the U.S. Department of Defense. This massive five-sided structure in Arlington, Virginia, emerged during a crucial period in American history when the nation needed a centralized military command center during World War II.
Construction of the Pentagon began on September 11, 1941, and the building was completed in just 16 months - a remarkable achievement considering its size and complexity. The project, overseen by General Leslie Groves, came to life through the efforts of thousands of workers who labored around the clock to create what would become the world's largest office building at the time.
Historical Origins and Planning
#The Pentagon's development emerged from the rapid expansion of the U.S. military during World War II. This historic period demanded a centralized military command center to coordinate defense operations effectively.
World War II and the Need for Space
#The War Department's personnel increased from 24,000 to 24,000,000 employees between 1939 to 1941. Military operations scattered across 17 buildings in Washington D.C. created communication challenges leading to delays in critical decision-making processes. The department's workspace requirements exceeded 1,000,000 square feet, prompting President Franklin D. Roosevelt to authorize a new consolidated headquarters.
- Five concentric rings connected by 10 spoke-like corridors
- Five floors with a total of 17.5 miles of corridors
- 7,754 windows for natural lighting
- Two 5-acre interior courtyards
- Five distinct wedge sections for modular construction
| Pentagon Design Statistics | Measurements |
|---|---|
| Original Footprint | 5.1M sq ft |
| Final Footprint | 3.7M sq ft |
| Corridor Length | 17.5 miles |
| Window Count | 7,754 |
| Interior Courtyards | 10 acres |
Construction Timeline
#The Pentagon's construction timeline exemplifies the remarkable speed with which this massive project progressed during World War II. The structure's construction spanned 16 months from groundbreaking to completion between September 11, 1941 to January 15, 1943.
Groundbreaking and Early Progress
#Groundbreaking began on September 11, 1941 at the Arlington Farms site in Virginia. Workers cleared 5.5 million cubic yards of earth debris within 3 weeks to prepare the marshy riverfront location. The first concrete was poured on October 1, 1941 with construction crews operating in three 8-hour shifts. By December 1941, 4,000 construction workers installed the building's foundation pilings at a rate of 15,000 feet per day.
- Hiring women construction workers for specialized tasks
- Creating onsite dormitories for 3,800 workers
- Establishing dedicated bus routes between Washington D.C. residential areas
- Operating commissaries 24/7 to feed construction crews
- Using prefabricated building components to accelerate assembly
| Construction Milestone | Date |
|---|---|
| Groundbreaking | September 11, 1941 |
| First Concrete Pour | October 1, 1941 |
| First Building Section Occupied | April 29, 1942 |
| Final Completion | January 15, 1943 |
Building Completion in 1943
#The Pentagon's construction reached its completion on January 15, 1943, marking a significant achievement in architectural history. The building's completion occurred ahead of schedule despite wartime material shortages and labor challenges.
First Employees Move In
#The first Pentagon employees occupied their offices on April 29, 1942, while construction continued in other sections of the building. Over 17,000 workers moved into the completed portions of the building during 1942 in a phased relocation strategy. The War Department staff transferred from temporary buildings throughout Washington D.C. into their new consolidated headquarters according to a precise departmental schedule.
Final Construction Details
#The completed Pentagon incorporated:
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29,000 tons of steel
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680,000 tons of sand
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435,000 cubic yards of concrete
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1,200 miles of electrical wire
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7,754 windows
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17.5 miles of corridors
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Installation of 41,492 concrete pilings
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Creation of five concentric rings
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Completion of two 5-acre interior courtyards
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Implementation of a sophisticated heating system with 16 miles of ducts
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Construction of 7 group underground parking areas
| Construction Element | Quantity |
|---|---|
| Total Cost | $83 million |
| Floor Space | 6.5 million sq ft |
| Land Area | 29 acres |
| Height | 77.3 feet |
| Floors | 5 |
| Bathrooms | 284 |
Architectural Features
#The Pentagon's distinctive architectural design incorporates unique features that optimize space utilization while maintaining efficient circulation patterns. Its innovative layout revolutionized office building design in the 1940s.
The Five-Sided Design
#The Pentagon's pentagonal shape emerged from the original building site's geometric constraints at Arlington Farms. The five equal sides measure 921 feet each with outer walls rising at 77 degrees. Each exterior wall contains limestone facades sourced from Indiana quarries measuring 4.5 inches thick. The building spans 28.7 acres with a center courtyard covering 5 acres.
Interior Layout and Structure
#The Pentagon's interior consists of five concentric rings labeled A through E from the center outward. The rings connect through 10 spoke-like corridors that facilitate quick navigation between sections. Key interior specifications include:
| Feature | Measurement |
|---|---|
| Total corridor length | 17.5 miles |
| Number of windows | 7,754 |
| Number of stairways | 131 |
| Number of escalators | 19 |
| Interior courtyards | 2 (5 acres each) |
| Total floor space | 6.5 million sq ft |
Each floor maintains identical layouts with standardized office dimensions. The building incorporates:
- Radial corridors spanning 50 feet wide
- Modular office spaces for flexible configurations
- Double-loaded corridors maximizing natural light penetration
- Built-in utility chases for mechanical systems
- Reinforced concrete frame construction with blast-resistant capabilities
The interior design enables occupants to walk between any two points in less than 7 minutes using a combination of corridors rings ramps.
Pentagon's Strategic Location
#The Pentagon's location in Arlington County, Virginia serves critical military strategic objectives. Its position across the Potomac River from Washington D.C. provides both security advantages and operational efficiency.
Why Arlington Was Chosen
#Arlington County emerged as the optimal location for several strategic reasons. The site sits on elevated ground 30 feet above the Potomac River providing natural flood protection. The War Department selected this location for its proximity to the nation's capital while maintaining a safe distance from potential naval attacks. The land cost $2.25 million in 1941 which was significantly less expensive than comparable sites in Washington D.C.
- Metro Rail: Direct access via the Pentagon Station on the Blue and Yellow lines
- Bus Routes: 14 regional bus lines connect to the Pentagon Transit Center
- Highways: Immediate access to Interstate 395 and Route 1
- Airport: 3-mile distance to Ronald Reagan Washington National Airport
- Helipads: 2 designated landing zones on the premises
- Parking: 67-acre lot accommodating 8,770 vehicles
| Transportation Type | Capacity/Details |
|---|---|
| Metro Station | 15,000 daily passengers |
| Bus Routes | 14 lines |
| Parking Spaces | 8,770 vehicles |
| Helipads | 2 landing zones |
| Distance to Airport | 3 miles |
Key Takeaways
#- The Pentagon was completed on January 15, 1943, taking just 16 months to construct during World War II
- Construction began on September 11, 1941, with groundbreaking at the Arlington Farms site in Virginia
- The building spans 6.5 million square feet, features five concentric rings, and includes 17.5 miles of corridors
- The first Pentagon employees moved into the building on April 29, 1942, while construction was still ongoing
- The total construction cost was $83 million, using 29,000 tons of steel and 435,000 cubic yards of concrete
- The building's distinctive five-sided design optimizes space utilization and allows people to walk between any two points in under 7 minutes
Conclusion
#The Pentagon stands as a testament to American engineering and wartime efficiency. Completed in just 16 months on January 15 1943 this massive structure continues to serve as the heart of U.S. military operations. Its innovative design incorporating five concentric rings maximizes space utilization while its strategic location ensures optimal security and accessibility.
The building's rapid construction during World War II showcases what's possible when innovation determination and resources align toward a common goal. Today the Pentagon remains not just a military headquarters but a symbol of American organizational prowess and architectural achievement.