Thomas U. Walter was an American architect best known for his work on the U.S. Capitol in Washington, D.C. He served as the chief architect during the mid-19th century and played a significant role in the building's expansion, particularly the design of its iconic dome. Walter's architectural style combined elements of Neoclassicism and Roman Revival, reflecting the grandeur of the period. In addition to the Capitol, Walter designed several other notable structures, including the Smithsonian Institution and various buildings in Philadelphia. His contributions to American architecture have left a lasting impact, showcasing his ability to blend functionality with aesthetic appeal.