Here's a popular shot taken in May, 2009. The Mississippi River is the reason for St. Louis' existence. 75, 100 or 150 years ago, long before the Arch, rows of commercial buildings downtown tumbled down to the edge of the levee and the waterfront was teeming with steamships. Now you can take a ride on an excursion boat like the one here. Check out this interesting and concise history of our riverfront.