The Gateway Arch is a 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 world’s tallest arch, the tallest monument in the Western Hemisphere, and Missouri’s tallest accessible building. 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. Louis. The arch sits at the site of St. Louis’ founding on the west bank of the Mississippi River. The Gateway Arch was designed by Finnish-American architect Eero Saarinen and German-American structural engineer Hannskarl Bandel in 1947. Construction began on February 12, 1963, and was completed on October 28, 1965, for $13 million ($175 million in 2012 dollars). The monument opened to the public on June 10, 1967.
