The Arch is located in downtown St. Louis, Missouri, along the Mississippi Riverfront. The Arch, also known as the Gateway Arch, is a monument that commemorates the Western expansion of the United States and is our Nation's tallest monument. The Arch is part of the Jefferson National Expansion Memorial which also includes the Old Courthouse and the Museum of Westward Expansion. A visit to the Arch is not complete without riding one of the innovative trams to the top.