From January 1st 2002, the Euro replaced the national bills and coins in the 12 Euro zone countries and from March 2002 all of those countries operated a single currency.

The Euro zone consists of the following countries: Austria - Belgium - Finland - France - Germany - Greece - Ireland - Italy – Luxemburg - Netherlands - Portugal - Spain.

Each euro zone member country had a different timescale for the collection and phasing out of notes and coins subject to individual banking policies. Even now, it is possible to use the original legacy currency in some countries to pay for items, and their main banks will exchange higher denomination banknotes for euros.

It is worth noting that any place that previously used one or more of the euro zone currencies has now also adopted the Euro. This applies to the Principality of Andorra, the Principality of Monaco, and the Republic of San Marino. It also applies automatically to any territories, departments, possessions, or collectivities of Euro-zone countries, such as the Azores, Balearic Islands, the Canary Islands, Europa Island, French Guiana, Guadeloupe, Juan de Nova, the Madeira Islands, Martinique, Mayotte, Reunion, Saint-Martin, Saint Pierre and Miquelon, to name just a few.

Although not the official currency, euros can be used to purchase items in larger towns and cities in the following countries: Turkey, Latvia, Russia, Montenegro, Switzerland, Bulgaria, Poland, Denmark, Lapland, Cyprus and the UK. However, it is probably still best to use the national currency of these countries, as the exchange rates offered can vary dramatically.

[Euro Currency Guide]