500 000 000 000 Mark Reichsbahndirektion

By late 1923, Germany's hyperinflation had outpaced the Reichsbank's ability to supply currency fast enough to be useful. Regional railway directorates — Reichsbahndirektionen — were authorized to issue their own emergency notes, Notgeld, to pay staff who needed wages denominated in figures the central bank's presses hadn't yet reached. The Frankfurt railway directorate's half-trillion Mark note is a product of that administrative collapse, printed locally by J. Maubach & Co. rather than through any central monetary authority.

The denomination itself is the detail worth pausing on: 500,000,000,000 Mark — five hundred billion — issued as a payroll instrument for railway workers.