Romania and Bulgaria signed the European Union’s Treaty of Accession, the last step to joining the Union.
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The Maastricht Treaty came into effect, and with it, the European Union was formed.
Britain voted to leave the European Union.
The name 'Euro' was officially adopted for European Currency.
The Paris Agreement was opened for signatures.
The UK's prime minister Boris Johnson compared himself to The Hulk in his efforts to steer the country out of the European Union.
