Looking southwest at the underside of the Seaman A. Knapp Memorial Arch over Independence Avenue SW in Washington, D.C., in the United States. The Jamie L. Whitten U.S. Department of Agriculture Building was completed in 1908. The South Building was built in phases between 1930 and 1936, and two skywalks (arches) built over Independence Avenue SW to allow workers to cross from building to building easily. The east arch is named for Seaman A. Knapp, a horticulturalist who essentially founded the cooperative extension service of USDA. The west arch is named for USDA Secreatry James Wilson, who served from 1897 to 1913. The underside of the arch is paved with Gustavino tile.