As of this writing, Historical Marker 373, all about Denmark, does not exist. It seems I was the first one associated with HMdb to notice this as you can see here.
What’s left is a sign telling you the name of the park. (The marker used to be just to the left.)
I looked all around the park for the marker, since I hadn’t looked at the HMdb pictures beforehand. I found this monument dedicated to the servicemen of the city of Denmark and this eerily familiar logo at the baseball park where the Denmark Vikings play ball.
I’m a little surprised the other Vikings allow this usage.