History of the Community Formation and the Modern Union Development. Main Treaties

Next step of integration - The Treaty of Nice (or Nice Treaty) - was signed by European leaders on 26 February 2001 and came into force on 1 February 2003. It amended the Maastricht Treaty and the Treaty of Rome. The Treaty of Nice reformed the institutional structure of the European Union to withstand eastward expansion, introduced common currency – Euro and started formation of the EU Constitution.14
Since the beginning of the union of six countries, the European Union has admitted new members in six waves. The first time the EU admitted new members after its foundation was in 1973 when Denmark, Ireland, and the UK acceded to the Community. After this so-called “First Northern Enlargement,” the next two expansions were toward the Mediterranean. Greece joined the Union in January 1981 (the first Mediterranean enlargement), with Portugal and Spain following suit in January 1986 (the second Mediterranean enlargement). The second Northern enlargement in 1995 saw Austria, Finland, and Sweden acceding to the EU.
In December 1997 Luxembourg European Council took the decisions needed to launch the fifth enlargement process. It stressed that the process must be all embracing, inclusive and responsive to events, and would proceed in stages at different rhythms depending on the degree of readiness of each of the applicant countries.
The fifth enlargement was the most extensive in the history of the Union, with ten countries being admitted at the same time in May 2004. This first Eastern enlargement absorbed Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia. Three years later, in January 2007, Bulgaria and Romania were granted EU membership rights as well.15
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