The Euro had two predecessors (kinda) - the European Unit of Account and the European Currency Unit. They weren’t day to day currencies, but they were used for

The Euro had two predecessors (kinda) - the European Unit of Account and the European Currency Unit. They weren’t day to day currencies, but they were used for things like cross-border bonds. The EUA was originally defined to be one dollar worth of gold back in the gold standard days. Each transition saw a 1:1 conversion with fluctuation - usually to benefit the EUA/ECU/Euro - along the way.