Why St. Louis' Famed Gateway Arch Is An Optical Illusion

When anyone hears the name St. Louis, one thing immediately comes to mind: The big arch, known officially as The Gateway Arch. Anyone who's ever visited the city knows that the arch can be seen from nearly everywhere within it. The arch is used in almost all marketing material for St. Louis, and including promotional videos from St. Louis tourism.

The arch is more than just a site to see though. It's also a destination that allows visitors inside. As noted on the Gateway Arch's official website, visitors can view exhibits in a museum on the ground floor. Then there's a tram ride which takes tourists to the top of the arch where they can view St. Louis in a unique way only visible from the famous structure itself. The arch website says that the tram experience usually takes 45 minutes, and includes a four-minute ride to the top and a three-minute ride back down.

The Gateway Arch website says that the structure was built to pay homage to an earlier time in the U.S. when the country began expanding westward. The official website says it pays tribute to Thomas Jefferson's vision. The monument is actually a U.S. National Park and as noted by the National Park Service, St. Louis was part of the famed Louisiana Purchase which allowed the U.S. to acquire significantly more land and expand west. As such, the arch is famously known as "The Gateway to the West," according to the Gateway Arch website. 

Interestingly, this National Park is open to everyone except for one elite group of people according to Architectural Digest. The website notes that U.S. Presidents are not allowed inside the arch. The Secret Service says the inside is too small and cramped posing a security risk to U.S. Presidents. One President, however, has taken the tram ride up. President Dwight Eisenhower was given that honor during a visit in 1967. Eisenhower was the president who signed the order for the construction of the arch 13 years earlier. When he showed up for a trip years later, though he didn't initially have plans to go inside, he insisted on being allowed in. 

Interestingly, there's something about the Gateway Arch that isn't immediately noticeable just by looking at it. The structure, according to the Gateway Arch website is 630 feet tall. But it's also 630 feet wide. Most people don't notice that the distance between the base of the legs is equal to the arch's height. But as Architectural Digest notes, the reason that's the case is because most people don't typically see the arch from head on. As a result, the structure almost always looks taller than it does wide. 

The arch website notes that the design of the arch was the idea of a Finnish-American architect named Eero Saarinen, the winner of a design competition in 1947. But interestingly, Eero's son Eliel had also entered the competition and at first the son was mistakenly told that he was the winner. Eventually, officials corrected their mistake.

The construction of the arch was very complex. Architectural Digest notes that originally it was predicted that there would be at least 13 fatalities during the monument's construction. Fortunately, however, no deaths actually occurred.