The U.S. National Arboretum is a 446-acre major center of botanical research. It conducts wide-ranging basic and developmental research on trees, shrubs, turf and floral plants. Nine miles of roadways wind throughout it, connecting the numerous gardens and collections. Some of the major ones include: aquatic plants, an Asian collection, flowering trees, the National Grove of State Trees, the National Bonsai and Penjing Museum and much more. The National Capital Columns (pictured) originally supported the old East Portico of the U.S. Capitol. They were removed during expansion of the Capitol in 1958 and placed at the arboretum during the 1980s.