This famous structure in St. Louis, Missouri, is part of the Jefferson National Expansion Memorial. It represents the “gateway to the west,” since St. Louis was a common launching spot for westward-going covered wagons.
It is hard to imagine how anyone can build ANY arch, let alone a smoothly-curving 630-foot tall arch that is hollow inside so people can ride a tram to the top!
But this short video loop shows the top of the arch being put into place on this day 45 years ago.
This is the tallest monument in the United States. Made of stainless steel skin covering a sandwich of two carbon steel walls with reinforced concrete in the middle, on the bottom half, and carbon steel and rebar, on the top half, this monument is exactly as wide as it is tall. The tram is an egg-shaped “elevator” with five seats per compartment and a flat floor. Because there are two bases (one on the north end, and one on the south end), and each base has a train of eight linked compartments, the tram can transport 80 passengers at a time. In each leg of the arch is a stairway for emergency use. I wouldn't like to be in the top when an emergency occurs—and have to walk down 1,076 steps!
Read more about arches. Try to build one, maybe!
This modern arch is truly and architectural wonder, but people have been making blocky arches since ancient times.
Here is a short webpage about creating arches. The key to making an arch out of boxes or out of pieces of wood or clay is to lay the arch out on a board laid flat on the floor. Then raise up the arch, take away the board, and see if your construction holds! (The website also suggests some books about arches and architecture.)
This website carefully details how to build a Roman arch with sugar cubes.