It is the world’s largest office building, and apart from the White House, the single structure that people all over the world immediately recognize as a symbol of American power. We are talking here, obviously, of the Pentagon, an oddly shaped building that houses the U.S. Department of Defense. Built on what was part of the estate of General Robert E. Lee, the Pentagon is impossible to miss when driving along Interstate 395 — a low, squat edifice unlike any other. Yet it is a relatively new addition to the cityscape of the nation’s capital. Steve Vogel, a veteran military reporter for the Washington Post, has finally written its story.

“The Pentagon” (Random House, 656 pages, $32.95) is a very long book and though very readable, somewhat oddly shaped. Slightly more than half of the book deals with the decision to build the structure in the first place — the financial and engineering challenges, the environmental constraints, the politics (both high and low). Roughly 40% of the remainder deals with other issues in which the Pentagon was merely the scene of major historical drama — the struggle to unify the armed services after World War II, the anti-Vietnam war protests, and the terrorist attacks of September 11, 2001.

At times Mr. Vogel summarizes the work of American military historians, at others he puts on display his superlative skills as a journalist with capturing human detail. Above all, he reminds us that history is made by living people, and he has a biographer’s fascination with the details of dozens of personalities who made the Pentagon what it is today. Particularly arresting is his portrait of Brigadier General Brehon Burke Somerville, the engineering officer who organized the construction of the building in a matter of months between 1940 and 1941.

A book of this kind delivers much more than it promises. It is not merely the history of a building, but the history of our country and, particularly, of its capital. It is also, inevitably, a history of the U.S. military establishment at its highest levels. It takes us back to an era that — though only seven decades back — seems as remote as the age of the pyramids.

It was a time when army officers assigned to duty in the capital wore civilian clothes to work (and many, in fact, did not even possess uniforms at all); when the American president (in this case, President Roosevelt) took an informed interest in civic architecture and applied a decidedly hands-on approach to improvements in Washington; when the administration was ramping up for a war that it knew we would enter when most Americans (including most members of Congress) hardly suspected as much.

At the time the decision was made to build the Pentagon, the War Department had just moved into a brand new building at 21st Street and Virginia Avenue (now occupied by the State Department; the WPA murals on the wall of the reception area, still in place, depict military rather than diplomatic episodes). To expend another $36 million on another structure (in the end, $72 million) seemed a wildly unnecessary extravagance. Nor did the odd shape of the proposed building inspire much confidence. Contemplating the architect’s plans, Senator Theodore Greene, a Democrat from Rhode Island, called it “a monstrosity.” But his hugely influential colleague Carter Glass, a democrat from Virginia, for all his 83 years, thought otherwise. So did the congressional delegation from northern Virginia. After many waspish debates and much leg pulling, Congress authorized the construction.

After the war there was much discussion of putting the building to other uses. There was some talk of using it to store U.S. military records, or of turning it into a hospital. There was even a plan to erect a 24-story office tower rising out of the central courtyard. Before any of these alternatives could take shape, the Cold War broke out in all its unlovely aspects. The Pentagon became the seat of the new Department of Defense. It also became an eventual target for critics and opponents of American foreign policy.

In one chapter — out of proportion to the narrative but riveting nonetheless — Mr. Vogel retells the story of the 1967 March on the Pentagon by anti-war protesters, and its unfortunate coda, the bombing of a section of the building by self-styled revolutionaries, led by William Ayres, now enshrined as distinguished professor of education at the University of Illinois in Chicago. It was only by a fortuitous accident that the device failed to kill or maim a half dozen black women custodians. The most wrenching chapter of all deals with the attacks of September 11. It makes for grisly reading. But in the current environment — when so many prominent figures in our public life would rather put that event behind us and discuss, say, prescription drug benefits — it is worth recalling.

Mr. Falcoff is a resident scholar emeritus at the American Enterprise Institute.