Kansas City, Mo. The KC skyline looking north. In the foreground is Union station. To the left is the Kauffmann Center For The Performing Arts and the tall glass buildings are One Kansas City Place (middle) and the AT&T Building (right). One Kansas City Place is the tallest building in the state of Missouri at 624 feet. Only the monument, Gateway Arch, in St. Louis, is taller at 630 feet which also happens to be the tallest man-made monument in the US.