One euro coin, coloured scanning electron micrograph (SEM). Euro coins and banknotes became legal tender across most of Europe on 1st January 2002. The national currencies replaced by the Euro ceased to be legal tender on 30th June 2002. This side of the coin, showing its denomination and a map of the European Union (EU), is the same for all the countries' coins. The other side varies from country to country. Magnification unknown.