2. The St. Louis Arch is a gigantic metal structure in the shape of an arch. It is located in St. Louis, Missouri. It is the tallest stainless steel structure in all of the world. It is 630 feet tall and weighs 17, 246 tons.

3.  I think that the St. Louis arch unique because it has no support beams but still it stays together with two parts planted on the ground. Most things I see have 3 or more areas planted in the ground. It includes an elevator to go up in. There is also a observation deck at the top with windows. This amazes me because I would think that it would completely unsafe to go there. It is also slanted up in there.

4. The purpose of the structure is a monument. It is a monument to how St. Louis helped in the western expansion of the united states. That is the purpose but there is more purpose To it. Another purpose is a tourist attraction, To look down below at St. Louis.