Euros were introduced after my last trip to Europe, so I'm not that familiar with them. Before the Euro, each nation had their own currency - although some smaller nations used other nation's currency, i.e., Luxembourg used Belgian and Luxembourg's Francs, but Belgium didn't take Luxembourg's. In the nations that I visited, each denomination was of a different size - one way to assist the blind. The Dutch Guilders also had different shapes that were embossed so you could feel them. The colors were amazing, as opposed to the United States' currency, which is one of the reasons why it's frequently counterfeited.