Which architectural style is reflected in the U.S. Capitol building, located in Washington, D.C.?

Neoclassicism is an intellectual and artistic movement that shared the thoughts, minds, and civic ideals of America. If something is classic, it implicitly is old. If something contains the prefix- 'neo-' then by definition it is new. So neoclassicism is the artistic style of 'new old stuff'.

Classical art and architecture refers to the traditions of ancient Greece and Rome. These two cultures set the foundations for European aesthetics, and for the early design of many government buildings in the the United States federal government.

The American government's neoclassical architecture is a style that links the American ideas of republican government and the legacy of ancient Rome. One of the most important American architects who advocated this type of style was Thomas Jefferson. The U.S. Capital Building wasn't designed by Jefferson, it was just sponsored by him.

In 1792, Secretary of State Jefferson opened a design competition for a building to house the U.S. Congress, to be called the U.S. Capitol. The government was being relocated to a new location along the Potomac River. The prize for the competition was $500 ($13,150 in 2018) and a lot in the Federal City.

In 1793, the amateur architect William Thornton was named when his design featured a white exterior, rows of columns and a sense of rational, calm logic. It was a stunning neoclassical design that was tweaked and amended over the years into the structure that houses the national legislature today.