500 000 000 Mark

Gelsenkirchen's half-billion Mark note dates from the autumn of 1923, when German municipal and regional authorities were legally permitted — effectively forced — to issue their own emergency currency, known as Notgeld, because the Reichsbank could not print fast enough to keep pace with hyperinflation. By the time notes of this denomination were entering circulation, prices were doubling in hours rather than days.

Stadt- und Landkreis Gelsenkirchen was a coal and steel district at the heart of the Ruhr, a region still reeling from the Franco-Belgian occupation that had begun in January of that year — a factor that accelerated the inflation catastrophe considerably. The currency reform of November 1923 rendered all such issues worthless almost immediately upon introduction.