The Acromion.

Lazy Sunday mornings...

"You know what acropolis means, right?"
"Uhm, I know the Acropolis [of Athens]," I responded.
"Well, akros- means highest point and -polis means city."
"Oh, right, right."
"Yeah, well, there's a bone (points towards his shoulder) that's known as the acromion because it's the highest point of the shoulder."