The Gateway Arch
Time Out says
Not only is St. Louis’s premiere attraction the world’s largest arch, but it is also the tallest man-made monument in the Western Hemisphere. Standing proud at 630 feet tall, this metal beauty was built in the mid-20th century as a monument to America’s westward expansion and is meant to signify the connection of the East to the West, honoring the country’s first pioneers. To fully understand this architectural wonder, snag a ticket on the Gateway Arch Tram and ride to the top of the monument.