Britain voted to leave the European Union.
The UK is the only country to formally leave the EU.
Source
The European Union is established as the Maastricht Treaty is signed.
MP's in the UK voted in favor of triggering the European Union Bill (Article 50), which gave the government the power to prepare to leave the European Union.
Romania and Bulgaria signed the European Union's Treaty of Accession, the last step to joining the Union.
The name 'Euro' was officially adopted for European Currency.
The people of Estonia voted to approve joining the European Union.
