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A project as large and complicated as the United States Capitol Building would be astonishingly difficult to finish under any circumstances. Considering that the project spanned the course of four presidential administrations, right under the noses of hundreds of super-empowered future tenants, as the major funding entity threatened to rip itself apart, that it was completed at all seems miraculous.

The Capitol’s formation gets a sparkling treatment from Guy Gugliotta, a journalist who covered Congress for the Washington Post before deciding to chronicle how the edifice itself got built. It’s really two stories: One narrative traces the artistic differences and ego-driven power struggles of the men who designed, funded, and constructed an expensive marble building. But Gugliotta couldn’t have done that story justice without framing it in the progression toward the Civil War, the ideological debates of which had everything to do with how the most iconic symbol of American democracy ought to look and feel.

Consider the cast of characters: Jefferson Davis, the slave-owning secretary of war who championed and guided the construction of the Capitol before leading the forces of the Confederacy against it; Thomas Walter, an experienced architect appointed by President Millard Fillmore to design the extension of the existing Capitol building; and Montgomery C. Meigs, a young Army engineer hired by Davis to execute its construction. Working with a trove of letters, Congressional transcripts, and diaries, Gugliotta turns yellowed correspondence into an almost novelistic account of how these men planned, built, and fought to keep the project moving.

And how they fought! Congress, which ultimately decided how much money Thomas and Meigs had to play with, gave little direction except that it “wanted a fabulous building, but they also wanted to look humble to their constituents by refusing to pay for it.” With every election, the team faced a new batch of intemperate lawmakers who demanded to know whether the plans would in fact work, and pushed to get contracts for their cronies. Perhaps the biggest challenge was rise of the anti-immigrant Know-Nothing party, which looked askance at artisans like Constantino Brumidi, an Italian whom Meigs brought in to paint the Capitol’s ornate frescoes.

The national debate over slavery filtered into the Capitol’s construction at every turn. For example, the book’s title refers generally to the Capitol dome, but more specifically to the giant bronze statue that sits atop it. In earlier versions, a sculptor had depicted the female embodiment of Freedom with a cap that in ancient Rome had been given to freed slaves. Davis objected to the symbolism, and Freedom got an eagle-shaped headdress instead. (Gugliotta doesn’t spend much time talking about the actual slaves who built the Capitol, confining his labor commentary to the argument over whether contractors or government workers were more efficient.)

It’s possible, however, that the Capitol wouldn’t have become as opulent as it is today if it weren’t for the march of war. At a time when sectionalism ruled, a home for the imperiled government was the only thing lawmakers could agree on, and they again and again voted to finance tile instead of brick, iron instead of wood, paint instead of whitewash. It was as much a monument to Meigs’ self-regard as anything: The engineer had his own name stamped on every cast iron strut and burned onto every wooden beam. By the end, his arrogant feud with Walter over who would get the credit—as well as his affiliation with Davis, when war broke out—got Meigs relieved of his Capitol duties and detailed to the Dry Tortugas.

Gugliotta’s epic is sometimes bogged down by the back and forth of political squabbles. But occasionally, those spats add color and grain to a story of sectional conflict that’s been told many times before.

Gugliotta reads at Politics & Prose at 7 p.m. on March 19. Free.