500 000 000 000 Mark Reichsbahndirektion

The Deutsche Reichsbahn issued its own emergency currency during the hyperinflation peak of late 1923 because the Reichsbank simply could not print and distribute legal tender fast enough to meet payroll and operational demands. Regional railway directorates — Reichsbahndirektionen — stepped in as quasi-monetary authorities, issuing notgeld denominated in figures that would have been unthinkable even months earlier. The Karlsruhe directorate was one of several that produced these high-denomination railway notes independently.

The embossed stamp is the sole security measure, which tells you something about both the desperation of the moment and the expected lifespan of the note — this was money designed to be spent within days, not saved.