Gateway Arch
 The Gateway Arch is a 630-foot-high (192 m) monument in St. Louis in the U.S. state of Missouri. Clad in stainless steel and built in the form of a flattened catenary arch it is the tallest man-made monument in the United States Missouri's tallest accessible building and the world's tallest arch. Built as a monument to the westward expansion of the United States it is the centerpiece of the Jefferson National Expansion Memorial and has become an internationally famous symbol of St.