This astonishing bed of steel is, at 630ft, the tallest man-made monument in the US. An early work by architect Eero Saarinen, was completed with much fanfare in October 1965 and has since come to symbolize St. Louis. The arch astounds for its scale, its construction and, most of all, for its shimmering skin and crisp geometry. Underground entrances at each foot access the visitor center.