Final answer:
Multiple architects, including Benjamin Henry Latrobe, Charles Bulfinch, and Thomas U. Walter, were responsible for the design of the U.S. Capitol Building.
Step-by-step explanation:
The U.S. Capitol Building, located in Washington, D.C., was designed by multiple architects. The original design was created by Dr. William Thornton, a physician and amateur architect. However, the final design of the Capitol Building was a collaborative effort involving several architects, including Benjamin Henry Latrobe, Charles Bulfinch, and Thomas U. Walter. Latrobe and Bulfinch played significant roles in the early stages of the design, while Walter's contributions later led to the completion of the building as we see it today.