20 000 000 Mark Reichsbahndirektion

The Reichsbahndirektion Köln was one of the regional directorates of the Deutsche Reichsbahn empowered to issue emergency money — Notgeld — during the hyperinflation of 1923, when the central banking system had effectively lost the ability to supply denominations fast enough to keep pace with collapsing purchasing power. Railway administrations across Germany became de facto local issuers out of necessity: workers needed wages in usable denominations, and the Reichsbank could not deliver them in time.

By the time a 20-million-Mark note was practical currency in Cologne, that sum would buy roughly a loaf of bread. The note's utility was measured in days.