The Gateway Arch
This monument was built in 1965 by Eero Saarinen, and it is placed in St. Louis, Missouri. The gateway arch was built to commemorate the expansion of territory to the west by American pioneers. This building is 630-foot high, and this is currently tallest memorial in the U.S. The main material is stainless, and many stainless panels attached the big arch shape exterior. What is characteristic of this building is that many physical and mathematical elements were needed to build the building to withstand the load well.
Here is the link of the Gateway Arch in archdaily.com :