Donald Siegfried Nelson, Dallas architect, was born in Chicago, Illinois, on February 10, 1907, the son of August G. and Diana (Frederickson) Nelson. He studied architecture at the Massachusetts Institute of Technology, where he earned a bachelor of architecture degree in 1927. He also attended the École des Beaux Arts in Fountainebleau, France, in 1925, and the École Normal Superieur des Beaux Arts in Paris from 1927 to 1930 as winner of the Paris Prize. He began his practice in Chicago in 1929 as a junior member of Bennett, Parsons, and Frost, architects and city planners, and in the early 1930s played a major role in planning the design of the celebrated 1933 Chicago Century of Progress Exposition.
In the spring of 1935 George L. Dahl, chief architect and technical director of the Texas Centennial Fair, invited Nelson and several other Chicago architects to come to Dallas and work on the exhibit. In addition to helping plan the layout and overall arrangement of the fair, Nelson designed the World Exhibits Building. Afterward he remained in Dallas and worked as architect for federal memorials for the Texas Centennial as well as operating a private practice in Dallas and Austin.
From 1942 to 1946 Nelson served as the chief of planning and design at the headquarters of the United States Army Air Force in Washington, D.C. After the war he formed a partnership with Thomas D. Broad in Dallas, where he continued to practice for the remainder of his career. Over the course of the next three decades Nelson established himself as one of the region's most noted architects. Among his best-known works are the Dallas Mercantile Bank complex (1940–47; additions 1957, 1959, 1964, and 1969); the Texas Memorial Grand Lodge Temple, Waco (1950); the original passenger terminal at Love Field (1957); the Dallas County Government Center (1969); and the Scottish Rite Library and Museum, Waco (1969). He was the recipient of numerous awards, including the Meritorious Design Award from the Texas Society of Architects (1950) and Progressive Architecture magazine's Design Award (1956). He was a member of the College of Fellows of the American Institute of Architects, the Architecture League of New York, and a charter member of the Texas Society of Architects. He married Matilda Fowler on September 17, 1929. The couple had one son. Nelson died in Dallas on January 4, 1992.