Originally built as Des Moines’ main post office in 1908, it was designed by James Knox Taylor, a Midwest architect who eventually became Supervising Architect of the United States Department of the Treasury. The original portion has classic Beaux Arts styling, built of Bedford limestone. The building was listed on the National Register of Historic Places in 1974. Woodburn & O’Neil and Wagner Marquardt Wetherell Ericsson designed the 1979 addition, an abstract version based on the original details.