The term ST. LOUIS LANDMARK is composed of two crossword solutions: ARCH (4 letters) and GATEWAYARCH (11 letters). The most iconic landmark in St. Louis is the Gateway ARCH, a 630-foot stainless steel ARCH that stands on the banks of the Mississippi River. It was designed by Finnish-American architect Eero Saarinen and completed in 1965. The ARCH is part of the Jefferson National Expansion Memorial and is a symbol of the city's role in the westward expansion of the United States.