2 Francs - King Leopold I of Belgium and King Frederick William IV of Prussia

Neutral Moresnet was one of Europe's strangest political accidents — a roughly 3.4 square kilometer territory left deliberately unresolved after the 1815 Congress of Vienna because neither the newly formed Belgium nor Prussia could agree on its possession, largely due to a zinc mine both wanted. It remained in administrative limbo until 1919. This coin, issued jointly under both sovereigns, is among the most unusual products of 19th-century European monetary arrangements — a condominium coinage for a territory that was never formally anyone's.

Extremely few were struck, and the piece exists today almost exclusively in institutional and specialist collections.