Gateway Arch is the nation's tallest memorial.

The structure is made of stainless steel and rises from a 60-foot foundation.

Cost: $30 million, shared by City of St. Louis and the federal government.

Although topped out in 1965 the dedication was in 1966.

The classic catenary curve sways 1/2" - 1" in 20 mph wind.

The underground Museum of Westward Expansion is below the arch. Admission is free, although there is a charge for the tram to the arch's observation deck.

The arch is exactly as wide as it is tall.

In 1990 this structure became the 21st recipient of the American Institute of Architects' prestigious Twenty-Five Year Award.

Tallest moument in the United States since 1965; to begin a tour of America's five tallest monuments, start with the Jefferson Davis Monument in Fairview, Kentucky.

The arch’s cross section is that of an equilateral triangle measuring 16.45 metres (54 feet) at the base, tapering to 5.2 metres (17 feet) at the apex. It is clad in stainless steel measuring 0.6 centimetres (0.25 inches) thick.

It was added to the National Register of Historic Places and named a National Historic Landmark in 1987.

The design competition was won by Eero Saarinen in 1947.