The 1970s and 80s led to the enlargement of the EC. Denmark, the United Kingdom and Ireland joined in 1973, Greece became a member in 1981, and Spain and Portugal joined the community in 1986. At the end of the 1980s communism collapsed in many eastern European countries. In 1990 a united Germany became the largest country in the community.

East and West Germans at Brandenburg Gate in 1989
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In the 1990s EC leaders started to seek greater cooperation in other fields. In 1991 the Maastricht Treaty was signed. Member states vowed to create a political union and introduce a single currency, the euro, which replaced the currency of 12 European countries in 2002.

In 1995 Austria, Sweden and Finland enlarged the European Union to 15 countries.

In the early years of the new millennium leaders of the EU started working on a constitution for all member states. They finished and approved it in 2004 but citizens in France and the Netherlands rejected it in national referendums.

The biggest enlargement took place in 2004. Ten new countries of central, eastern and southern Europe entered the EU: Cyprus, Malta, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia. Romania and Bulgaria became members three years later. In 2013 Croatia became the last country to join the EU.

One and a half decades after the fall of the Iron Curtain the division of Europe had been overcome.