[two_third]

Size: Frisbee

Recorded: June, 2014

Found: Manitowoc, Wisconsin

Circa: 1962

Made: USA, USSR

Material: Brass

Status: Known

At first glance, it looks like some sort of manhole or utility cover. After all, it’s in the middle of the street… what else could it be? It’s actually something so unique, that a granite plaque commemorates it on a nearby sidewalk. It’s likely the only one of its kind in the world.

Hint 1:

Spoiler It’s placement was by accident. [collapse]

Hint 2:

Spoiler It serves no practical purpose. [collapse]

Answer: