Demonetization
  
International travelers to Europe prior to 2002 and the introduction of the Euro might actually have saved their French Francs, Spanish Pesos, German Deutsche Marks and Italian Lira are holding the remnants of demonetization. In basic terms, demonetization occurs when a government decides to change its currency to address inflation, facilitate trade (such as with the Euro and the EU), to combat counterfeiting, or to halt black market cash proliferation.
Brazil is an example of a nation that has deployed demonetization on several occasions. The first cruzeiro was introduced in 1942. Due to inflation, a different cruzeiro was commenced in 1967. 1987 saw a switch to a new currency, the cruzado. The cruzeiro was reintroduced in 1990, only to be replaced yet again to the real in 1993, which is still the national currency.
Due to economic and civic unrest as a result of the large influx of Middle Eastern migrants into Western European nations advocated by Germany and the EU, Italy and France have growing domestic movements to follow the UK’s Brexit. If this happens, perhaps those old Francs and Deutsche Marks may be worth something again.