50 Kronen (CN stamp)

After the First World War, Fiume's political status became one of Europe's most intractable disputes — claimed by both Italy and the newly formed Kingdom of Serbs, Croats and Slovenes, governed by neither for years. The city's provisional administrations issued their own currency by overprinting existing Austro-Hungarian notes rather than printing anything new. This 50 Kronen carries the "CN" stamp standing for *Città di Fiume* (or *Comune di Nettuno*, depending on which administrative phase applies), converting an imperial note into a local one by bureaucratic ink alone.

The overprint series is notoriously prone to forgeries, both contemporary and modern. Authentication hinges on the stamp's ink saturation and registration against the underlying note's paper.