The Gateway Arch is the most recognizable symbol of the city of Saint Louis. The 630-foot tall stainless steel arch commemorates the great westward expansion of the United States as thousands of people packed up everything they had and made their way west to carve new lives out of the wilderness. Surrounding the arch are 90 acres of grass and parks. In fact, the grounds are all a national park, and the monument is the tallest man-made national monument in the United States.. Below the sod is an extensive pioneer museum featuring artifacts and films documenting westward expansion. There is also a film showing the construction of the arch itself. A fire closed Gateway Arch in 1998, but it has since reopened to visitors. For a fee, you can squeeze into a mechanical egg that will carry you up to the top where two rows of windows provide views to the east and the west. At the top the arch is designed to sway up to 18 inches in strong winds and earthquakes.