Editor's note: The Gateway Arch makes it one of the most instantly-recognizable skylines in the U.S. At 630 feet, the Arch is the tallest monument in the country, and the very brave can ride to the top via a tram. Incredible views on a clear day! But back to St. Louis’s skyline: if you can go there, enjoy it via a riverboat cruise along the Mississippi. If you can’t get away just now, check out these fabulous St. Louis Skyline wallpapers!