Looks to me like it actually says “SCHEMNITZ”, not Chemnitz. That's the old German name for an industrial town that was originally in the Austrian-Hungarian Empire. Since the creation of Czechoslovakia in 1919, it has been referred to by its Slovak name of Banská Štiavnica.
The town has two castles: Starý zámok (the Old castle) and Nový zámok (the New castle, although it’s 16th Century).
It’s a nice find. These wind caps are colloquially known as “bonnets”.