Cryptic Memorial

At the castle at Schriesheim near Heidelberg someone has written

XI. Olympiade
Berlin
-1936-

beneath an air duct.

It's too neatly written to be an impulsive piece of graffiti. And since it's on one of the main passageways, the management has clearly allowed it to remain. What could it mean?

No one can explain its significance. When I think of the 1936 Olympics I remember Jesse Owens and his four gold medals. I wonder what the author was thinking?