Interesting Eric that you mention guns because there is a connection.
The structure is called a "shot tower" and used to create perfectly round shotgun pellets. The following is the Wikipedia story about this one located in Iowa. An interesting read.
There is a similar tower in Corning, New York and they used that one for drawing long thin glass tubes for thermometers and other instruments.
Shot Tower (Dubuque) - Wikipedia
en.wikipedia.org
So class that is all for today. Make sure your homework is done for tomorrow and you may resume drinking now.
I read the wiki link but still am puzzled.... Where did they melt the lead and how the heck did they get it up to the top to pour it I wonder...