Colossal: LIFE at the Birth of the Pentagon

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Updated: | Originally published: ;

The Pentagon — and, by extension, the U.S. military — has become such a prominent and obvious symbol of American might over the years that it’s easy to forget that the world’s largest office building and home of the Department of Defense is just that, a building, albeit one with some mighty impressive stats, and some sobering history, attached to it.

For example:

— Despite having 3,705,793 square feet for offices, concessions, and storage and a gross floor area of 6,636,360 square feet, the Pentagon is designed so that, ideally, it takes at most seven minutes to walk between any two points in the building.

— Five-and-a-half million cubic yards of earth and 41,492 concrete piles were necessary for the foundation of the building, as well as 680,000 tons of sand and gravel from Potomac that were processed into 435,000 cubic yards of concrete.

— Roughly 200,000 telephone calls are made daily from the Pentagon. (In the pre-cell phone days of the early 1940s, 100,000 miles of telephone cable — enough to circle the globe four times — helped make all that communication possible.)

— Ground was broken for construction on the Pentagon on September 11, 1941 — 60 years to the day, incidentally, before one of the airliners hijacked by terrorists on 9/11, American Airlines flight 77, slammed into the western side of the building, killing 184 people, 125 of them in the Pentagon itself.

The people who actually worked inside the Pentagon, meanwhile, were initially underwhelmed by the building, LIFE wrote in December 1942. Both employees and visitors “resent the eight and two-fifths miles of barren corridors, the jammed ramps, the pile-up at entrances and exits, the parking and transportation problems, the six overcrowded cafeterias, the staggered working hours.”

Here, LIFE.com presents a series photos — most of which never ran in LIFE — of the iconic, colossal edifice under construction more than seven decades ago.

Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.

Correction: The original version of this story misstated the number of years between the groundbreaking ceremony for the Pentagon and the Sept. 11, 2001 terrorist attacks. The attacks were exactly 60 years later, not 70 years later.

Building the Pentagon, 1940s
Building the new home of America's War Department, 1941. (The name "Department of Defense" would not come into use until 1947.)Thomas D. McAvoy—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. Architects and draftsmen work on plans for the Pentagon's construction in the partially completed building in 1942. Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. A massive map provides an overview of the Pentagon highway network. With a complex housing roughly 23,000 workers and 16 parking lots for over 8,000 cars, new roads to accommodate the traffic were a necessary part of the construction.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
In a May 1943 issue, LIFE noted that the exterior of the Pentagon "has a gray limestone façade, although more than half of the building's substance is sand and gravel dredged from the bottom of the Potomac River."Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
An officer chats with a worker by one of the large exhaust fans at the Pentagon, 1940.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. A woman occupies a desk in the colossal office space in the "War Building." Thomas D. McAvoy—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. Workers would ultimately complete seven floors for the Pentagon: five of them above the ground and two beneath.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. The Pentagon, 1941.Myron Davis–TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. Perhaps no other single fact about the Pentagon's construction is more amazing than this: when construction began on September 11, 1941, LIFE reported, the groundbreaking took place "only two weeks after the designing [of the structure] commenced."Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. The Pentagon was built in a mere 16 months for approximately $83 million.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. Among the more random facts about the Pentagon: the building contains an estimated 4,200 clocks — all running, one presumes, on military time.Myron Davis–TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. Standing guard in a still-under-construction corridor. The Pentagon boasts 17.5 miles of hallways.Myron Davis–TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Not published in LIFE. The Pentagon has 284 rest rooms.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
A view showing one of the five sides of the then-War Building. Today the Pentagon is surrounded by 200 acres of lawn.Thomas D. McAvoy—TIME & LIFE Pictures/Getty Images
Not published in LIFE. Men at work inside the Pentagon, 1941.Myron Davis—TIME & LIFE Pictures/Getty Images
Not published in LIFE. Paper has long been an important part of the Pentagon culture; the Department of Defense Post Office deals with about 1.2 million pieces of mail monthly.Myron Davis—TIME & LIFE Pictures/Getty Images
A serviceman talks to a receptionist in the newly constructed Pentagon in 1941. There is a private sector at the Pentagon: for instance, the restaurant service is handled by a privately run civilian operation that is under contract to the Pentagon.Thomas D. McAvoy—TIME & LIFE Pictures/Getty Images
Not published in LIFE. Sending files via the Pentagon's pneumatic tube system — an old-school delivery mechanism that, as late as the mid-1980s, was still handling more top-secret information than the Defense Department's computers.Myron Davis—TIME & LIFE Pictures/Getty Images
The official War Office seal on the china used in a private dining room at the Pentagon.Myron Davis—TIME & LIFE Pictures/Getty Images
Part of the suite for the highest ranking officer at the Pentagon, circa 1942. As LIFE wrote in a December issue that year, the Secretary of War "has a roomy, carpeted office with comfy overstuffed leather chairs. He sits at the handsome desk which has been inherited by every Secretary of War since Robert Todd Lincoln in 1883. At his right is a direct wire to the White House."Myron Davis–TIME & LIFE Pictures/Getty Images
A private kitchen built to serve the highest ranking Pentagon officials and their guests, should they wish to avoid one of the building's six cafeterias.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
Part of the suite for the Secretary of War. LIFE wrote in December 1942: "The only really happy person in the War Department's whopping new reinforced-concrete 'home' is the Army's civilian chief, Henry L. Stimson." (Stimson was Secretary of War at the time. This post would later be eliminated when the Army and Navy were split into separate departments; the job of Secretary of Defense was added to ensure cooperation between them.)Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
A man presses a button in the elevator reserved for the highest ranking officer at the Pentagon and his guests. The Pentagon boasts 13 elevators, 19 escalators, and 131 stairwells.Myron Davis—TIME & LIFE Pictures/Getty Images
Building the Pentagon, 1940s
From the private washroom that was part of the suite for the Pentagon's top man. LIFE noted in May 1943: "There is a medicine chest, toilet, and a stall shower but no bathtub."Myron Davis—TIME & LIFE Pictures/Getty Images

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