A colossal arch built along the west bank of the Mississippi River in St. Louis, Missouri. The stainless steel arch, 630 feet (192 m) wide and rising 630 feet (192 m) above the banks of the river, was designed by Eero Saarinen and was built 1963–65.
Definition of Gateway Arch in US English:
Gateway Arch
proper noun
A colossal arch built along the west bank of the Mississippi River in St. Louis, Missouri. The stainless steel arch, 630 feet (192 m) wide and rising 630 feet (192 m) above the banks of the river, was designed by Eero Saarinen and was built 1963–65.