Sadly, the Gateway Arch is showing signs of corroding.
The Arch is one of my favorite monuments, standing on the western bank of the Mississippi, symbolizing and inviting one to embark upon the great trek to new territory. St. Louis was part of the Louisiana Purchase; Lewis and Clark geared up for their expedition on the east side of the river at Camp Dubois; and St. Louis was a key port for steamboat traffic in the 19th and early 20th centuries.
Here is a picture of the Arch I took last year when in St. Louis to interview sports entrepreneur David Checketts for Kaizen.