Who designed the United States Capitol dome completed during the American Civil War?

Thomas Ustick Walter designed the United States Capitol dome that was completed during the American Civil War.

Walter, the fourth Architect of the Capitol, proposed a larger cast-iron dome to replace the Capitol’s smaller copper-covered dome. Construction began in 1855, and the new dome was completed in 1866, after the war had ended. Its design uses an inner and outer shell supported by cast iron, making it both an engineering project and a powerful national symbol.

The dome’s crowning Statue of Freedom was designed by Thomas Crawford and placed in position in December 1863. Because the dome rose over the Capitol while the country was divided, its completion became a visual statement of Union continuity.

The Capitol itself predates the Civil War and was designed or altered by several architects, including Benjamin Henry Latrobe and Charles Bulfinch. That is why those names can seem plausible in this question. Walter specifically designed the present dome, while Crawford created the statue above it. The building’s long construction history links the founding government to later national development.