Gateway Arch

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The Gateway Arch is a gleaming stainless-steel arch on the bank of the Mississippi River in St. Louis, Missouri, in the United States. At 192 metres (630 feet), it is the tallest arch in the world and the tallest monument in the country. It stands on the spot where St. Louis was founded in 1764.

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At a glance

Country: United States
Location: St. Louis, USA
Built: 1965
Height: 192 m
Type: Monument

Quick answers

Where is Gateway Arch?

Gateway Arch is in St. Louis, USA, United States.

When was Gateway Arch built?

Gateway Arch was built in 1965.

How tall is Gateway Arch?

Gateway Arch is about 192 m tall.

A stainless-steel arch honouring westward expansion; at 192 m it is the world's tallest arch.

The arch honours the westward expansion of the United States and the people who made it happen, from President Thomas Jefferson to explorers such as Lewis and Clark and the pioneers who followed. That is why it is often called the "Gateway to the West". It was designed by the Finnish-American architect Eero Saarinen and is the centrepiece of Gateway Arch National Park. The arch opened to the public in 1967.

How it was built

Saarinen won a design competition in 1947 against 172 entries. Construction began on 12 February 1963, when the first steel section was lifted into place on the south leg, and the last piece was set at the top on 28 October 1965. The arch is made of 142 stainless-steel sections shaped as triangles that get smaller towards the top. Each leg's walls are a sandwich: stainless steel outside, carbon steel inside, and concrete in between up to about 91 metres. Each leg stands on a concrete foundation 18 metres deep.

Its special shape

The arch's curve is a catenary, the shape a hanging chain makes when you hold it at both ends, turned upside down. Saarinen used a "weighted" catenary, as if the chain had heavier links near the ends and lighter ones near the top, which changes the curve slightly from a plain chain. The arch is exactly as wide at its base as it is tall: 192 metres both ways. It is built to sway slightly in strong winds, up to about 46 centimetres either way, and to withstand earthquakes.

Riding to the top

Visitors reach the top in a tram that runs up inside each leg. Each tram is a chain of eight small round capsules, each holding five people, and the capsules tilt as they climb so riders stay upright, a bit like the cars on a Ferris wheel. At the top is a narrow curved viewing room with 16 small windows on each side, where on a clear day you can see about 48 kilometres. The tram began running in 1967, and a new museum under the arch opened in 2018.

Fun facts

The Gateway Arch is as wide at its base as it is tall: 192 metres.
A time capsule holding the signatures of 762,000 students and others was welded into the top piece of the arch.
Each tram capsule seats only five people, and they rotate like Ferris-wheel cars as they ride up the curve.
Building the arch used about 900 tons of stainless steel, more than any project before it.