The Gateway Arch
The Gateway Arch, at 630 feet, is the tallest national monument in the United States. At the base, it is also 630 feet. It is located in St. Louis Missouri, and took $13 million to build. Workers started to construct on February 12, 1963, and was completed on October 28, 1965. It was released to the public on July 24, 1967. The Gateway Arch weighs over 43,000 tons. 900 tons of stainless steel were used to build it, and that is more than any other project in history. The Gateway Arch goes 60 feet below ground to keep it stable.