Bunk.

Just one of a few machine gun nests leftover from the Civil War. This one is in the middle of a large park on the northwest side of the city. No plaque, no explanation of what it is or why it's there.

I'm not even really sure why it wasn't torn down, other than perhaps inertia. Anyway, this one was part of a series that ran along the university campus, the site of many bloody urban battles.