Louisiana Through My Lens - Why is there a Cannon embedded in a Baton Rouge Sidewalk?

Anyone walking down 3rd Street in downtown Baton Rouge, Louisiana, may notice a strange cylindrical metal object sticking out of the sidewalk. The object is quite obscure, leading many to believe it could be an old sewer pipe or something similar. Most people who pass by tend not to give it a second thought. 

However, if you happen to be curious about this unusual object embedded in the sidewalk, a nearby historical marker might provide some clues.