20 Francs

The Banque Nationale de Belgique was only established in 1850, the same year this note was issued — making P#41 among the earliest instruments produced by an institution that was itself brand new. The National Bank had been founded by royal decree in March of that year, absorbing the functions of the Société Générale which had served as a de facto central bank since 1822.

Léopold Wiener was primarily a medallist and engraver rather than a banknote designer — his involvement reflects how early Belgian paper currency drew on the country's established tradition of medal and coin artistry rather than specialist security printing expertise.