He was also involved in the debates about the annexation of Texas and an Oregon boundary dispute in 1844 that led to the establishment of the U.S-British boundary at the 49th parallel north, the result of the Oregon Treaty (1846). While serving as a member of Congress, Owen introduced and helped to secure passage of the bill that founded the Smithsonian Institution in 1846. Owen was appointed to the Smithsonian Institution's first Board of Regents and chaired its Building Committee, which oversaw the construction of the Smithsonian Institution Building in Washington, D.C., and recommended James Renwick, Jr. as architect, James Dixson and Gilbert Cameron as the contractors, and the Seneca Quarry for its distinct, dark-red sandstone. Owen, his brother David Dale Owen, and architect Robert Mills, were involved in developing preliminary plans for the Smithsonian Building. These early plans influenced Renwick's choice of the Romanesque Revival architectural style (sometimes referred to as Norman-style architecture) and his three-story design for the building, which was finally selected, although not without controversy. Owen's book Hints on Public Architecture (1849) argued the case for the suitability of Renwick's Romanesque Revival (Norman) architectural style for public buildings such as the Smithsonian "Castle," which he discussed in detail. Seven full-page illustrations and details of the building's architectural elements were prominently featured in the book, leading some to criticize Owen for his bias toward Renwick and his preference for Norman-style architecture over other popular styles. U.S. diplomat Owen was defeated in his bid for re-election to Congress in 1846; however, he remained active in public service and was once again elected to serve in the Indiana General Assembly. On 24 May 1853, while Owen was serving as a state legislator in Indiana, President Franklin Pierce appointed him as U.S. minister (Chargé d'Affaires and Minister Resident) to the Kingdom of the Two Sicilies at Naples. Owen served in the diplomatic post until 20 September 1858, and then retired from political life, although he remained actively interested in public affairs and social reform issues. Other political activities During the American Civil War, Owen served in the Ordnance Commission to supply the Union Army; on 16 March 1863, he was appointed to the Freedman's Inquiry Commission. The commission was a predecessor to the Freedmen's Bureau. In 1862 Owen wrote a series of open letters to U.S. government officials, including President Abraham Lincoln and U.S. Secretary of the Treasury Salmon P.