The Jefferson National Expansion Memorial is in St. Louis, Missouri, near the starting point of the Lewis and Clark Expedition. It was designated as a National Memorial by Executive Order 7523, on December 21, 1935, and is maintained by the National Park Service (NPS). The memorial consists of a 91-acre (36.8 ha) park along the Mississippi River on the site of the earliest buildings of St. Louis; the Old Courthouse, a former state and federal courthouse that saw the origins of the Dred Scott case; the 45,000 sq ft (4,200 m2) Museum of Westward Expansion; and most notably, the Gateway Arch, an inverted steel catenary arch that has become the definitive icon of the city.
The Gateway Arch is known as the "Gateway to the West". It was designed by Finnish-American architect Eero Saarinen and structural engineer Hannskarl Bandel in 1947 and built between 1963 and October 1965. It stands 630 feet (192 m) tall and 630 feet (192 m) wide at its base. The legs are 54 feet (16.5 m) wide at the base, narrowing to 17 feet (5.2 m) at the arch. There is a unique tram system to carry passengers to the observation room at the top of the arch.