San Marini is another nation which used the European Euro. The European euro is used by the country which is a member of the Eurozone. Eurozone is the area of the Europe where all the countries use euro.
The people of San Marino takes pride on their heritage and roots which can be traced back to Ancient Rome. In fact, their form of government that has 2 heads of state ruling at the same time is a remnant of an old Roman Empire practice.