The Gateway Arch is a 630-foot-tall (192 m) monument in St. Louis, Missouri. Clad in stainless steel and built in the form of a weighted catenary arch, it is the world’s tallest arch and Missouri’s tallest accessible building. Some sources consider it the tallest human-made monument in the Western Hemisphere.  Built as a monument to the westward expansion of the United States and officially dedicated to “the American people”, the Arch, commonly referred to as “The Gateway to the West”, is a National Historic Landmark in Gateway Arch Nation Park and has become an internationally recognized symbol of St. Louis, as well as a popular tourist destination. From Wikipedia