EMU

The European Economic and Monetary Union (EMU) is the project that is meant to be a monetary union with a harmonized economic policy to focus. Within the European Union the EMU project was launched in 1990 with a three-phase plan. EMU was created by the Treaty of Maastricht in 1992. In 1999, the EMU actually realized. Currently taking 17 of 28 EU Member States on the third and final stage of EMU. They use the Euro as currency and coordinate their economic and financial policies in the framework of the Eurogroup.
Given the crisis that prevails in Europe (except Germany) it does not seem like such a successful operation.

I think we were better off if each country had retained its own currency and economy.

In 2009 EMU was 10 years and for the occasion of this "milestone", the countries issued a special 2 Euro coin imprinted with:

EMU 1999-2009

(This picture was taken with a reversing ring on the device to attache a 28mm lens reversed on the device. The macro magnification is 3:1 . There is no crop occurred.)