The European Union is a unique form of supranational organisation established as a result of the process of co-operation and stabilisation which was initiated in 1951 between six European countries: Belgium, France, Germany, Italy, Luxembourg and the Netherlands. After more than fifty years of existence and five waves of enlargement, the European Union at present has 27 Member States that together have 492 million citizens.
The term 'European Union' was introduced following the Treaty on European Union signed in 1992 in Maastricht. The structure of the European Union is very often presented by three pillars at the front of an antique temple. The first pillar relates to most of the Union's common policies (where decisions are reached within the institutional triangle between the Commission, the Council and the Parliament). The second pillar is made of common foreign and security policies, while the third one consists of co-operation in justice and home affairs.
 

1950 - Schuman Plan on the establishment of the European Coal and Steel Community presented

1951 – Treaty establishing the European Coal and Steel Community signed (the Treaty of Paris)

1952 – Treaty establishing the European Defence Community signed

1957 – Treaty establishing the European Economic Community and the Treaty establishing the European Atomic Energy Community signed (Treaties of Rome)

1960 - European Free Trade Association (EFTA) founded

1962 – Common Agriculture Policy (CAP) introduced

1973 – The first wave of enlargement (Denmark, Ireland, the United Kingdom of Great Britain and Northern Ireland)

1974 – Heads of governments and states of EU member states decided to meet 2 to 4 times a year as the European Council

1974 – It was decided that MEPs for the European Parliament would be elected by direct election

1979 – European monetary system entered into force

1979 – First direct elections for the European Parliament held

1981 – Second wave of enlargement (Greece)

1986 – Third wave of enlargement (Spain, Portugal)

1986 – Single European Act signed

1989 – Fall of the Berlin Wall

1989 - PHARE programme initiated

1990 – Agreement establishing the European Bank for Reconstruction and Development signed

1990 – Schengen Convention on the abolition of border checks between  signatory states concerning issues and guarantees for the free movement of people introduced

1990 – Germany re-united

1992 – Treaty on European Union (the Treaty of Maastricht) was signed

1993 – Single market created

1993 - Single criteria for membership of the European Union (the Copenhagen criteria) established

1995 – Schengen Convention entered in force

1995 – fourth wave of enlargement (Austria, Finland, Sweden)

1995 – Madrid criteria (administrative criteria) for EU membership defined

1997 – Treaty of Amsterdam signed

1997 – European Commission published  Agenda 2000

1999 - Eleven EU countries entered into the third phase of monetary union and accepted the euro

2000 – Greece fulfilled the convergence criteria for the adoption of the euro

2001 – Treaty of Nice on the composition and activities of EU institutions after enlargement signed

2002 – Euro coins and bills entered into circulation

2002 – Convention on the Future of Europe started

2003 - Draft of the Constitutional Treaty presented

2004 – Fifth wave of enlargement (Cyprus, The Czech Republic, Estonia, Latvia, Lithuania, Hungary, Malta, Poland, Slovakia, Slovenia)

2004 – European Council adopted the final text of the Constitutional Treaty

2006 – Council of the European Union adopted a new instrument of pre-accession assistance – the IPA, replacing the previous pre-accession financial instruments - PHARE, ISPA, SAPARD and CARDS

2007 – Finalisation of the fifth wave of enlargement – accession of Bulgaria and Romania

2007 - Slovenia introduced the euro

2007. – Heads of state and governments signed up to a detailed mandate for an Intergovernmental Conference (IGC) to hammer out the details of a new "Reform Treaty" to be adopted at the end of the year.