Eurozone
From Tardis Wiki, the free Doctor Who reference
The Eurozone or EZ was an Earth superpower which competed with the United States of America in the early 21st century. It was composed of 25 European countries, including the United Kingdom and France. It's form of currency was "euromarks" and it had a Space Agency. (PROSE: Trading Futures, AUDIO: The Feast of Axos)
At some point during the 21st century, the Eurozone closed its borders. (AUDIO: Hothouse)
Behind the scenes
In reality, the Eurozone is the collection of European countries that have given up their currencies and adopted the 'euro'.