The Gateway Arch is a 630-foot (192 m) monument built to honor westward expansion. 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, and the world's tallest arch. It stands on the banks of the Mississippi River. Designed by Eero Saarinen and Hannskarl Bandel in 1947. Construction began on Feb. 12, 1963, and ended on Oct. 28, 1965, costing $13 million approx. $94,700,000 in 2013. Publicly openedn June 10, 1967.