The Gateway Arch was designed by Finnish-born designer, Eero Saarinen, one of the masters of American 20th century architecture (you'll be seeing more of his works in the future). In 1947, he was chosen from 172 applicants in a competition to provide a monument recognizing St. Louis' importance in settling the west. This was his first project as an independent architect. In approaching his design he felt to "... create a monument which would have lasting significance and would be a landmark of our time... Neither an obelisk nor a rectangular box nor a dome seemed right on this site or for this purpose. But here, at the edge of the Mississippi River, a great arch did seem right."
The arch stands at 630 feet making it America's tallest monument- and impossible to take a picture of up close. It is a "catenary arch"- the shape a chain takes when held at both ends. The interior of the arch does not require much interior framing, due to Saarinen's use of a stressed metal skin to carry the structural load.
His unique design, required unique construction techniques. The first triangular section was put in place in 1963. The leg bases were built from the ground up, requiring specific measurements and surveying to ensure that the legs would meet at the apex. The margin for error was 1/64th of an inch! Construction began with cranes, and after it spanned taller than a crane could reach, special 100-ton "creeper cranes" that ran on steel tracks mounted to each leg were utilized. As construction progressed, track was added allowing the cranes to continue building. Construction was completed in 1965 without a hitch, which is amazing considering that they did not use computer technology. Sadly, Eero Saarinen died in 1961 before construction began on the arch.
I personally find the arch's immense scale, angles, simplicity, and sculptural form stunning and beautiful- especially, when standing close. It is a monument that we grow up hearing about and seeing pictures of (and perhaps consider a little cheesy), but visiting in person definitely gives you a new respect for it. If you ever get the opportunity, you should definitely see the arch and take a tram ride to the top- unless you are claustrophobic or afraid of heights.