[AMERICAN ARCHITECTURE]. WALTER, Thomas Ustick (1804–1887). An Original Proposed Plan for the Second Story of an Unknown Structure, 16 June 1835. One page, folio 508 x 384 mm, ink and wash, signed and dated in lower corner, old fold with some separation near margin. Walter was an American architect known for his Greek Revival architecture in the Philadelphia area. He was one of the founding members and the second president of the American Institute of Architects that today has more than 95,000 members that are licensed architects and associated professionals. However, “Walter is better known, however, for the additions that he made to the U.S. Capitol in Washington, D.C., and especially for the massive cast–iron dome with which he replaced the earlier low wooden one (1855–63)” (Britannica). In 1850, Walter entered the competition for the design for the extension of the United States Capitol and was selected with his plan that more than doubled the size of the existing building and added the iconic dome. Construction began in 1851 and was nearly completed in 1863 when the Statue of Freedom was placed on top. For Walter’s accomplishments, he is honored in a ceiling mosaic in the East Mosaic Corridor at the entrance to the Main Reading Room of the Library of Congress. The Thomas Walter Ustick Collection is housed at the Athenaeum of Philadelphia. AN EARLY AMERICAN ARCHITECTURAL DRAWING BY AN IMPORTANT AMERICAN ARCHITECT.