The principal architect behind the design of the U.S. Capitol building was William Thornton, who won the design competition in 1792. The Capitol, located in Washington, D.C., serves as the meeting place for the United States Congress. Thornton's design was inspired by classical Roman architecture, reflecting ideals of democracy and governance. Various modifications and enhancements were made to the building over the years, but Thornton's original vision laid the foundation for one of the nation's most iconic structures, symbolizing the legislative power of the United States and its commitment to democratic principles.