Europe: London's European machinery and anti-EU offices
26 June 2014 Last updated at 12:46 BST
Some may think Brussels and Strasbourg are full of EU and European institutions, but London has plenty of its own.
Westminster is home to many groups that are for and against European integration, and there are many others across the capital, dedicated to taking Britain out of - or further in to - the European Union.
Adam Fleming reports on their proliferation in a Daily Politics film, where he spoke to Rory Broomfield of the Better Off Out campaign.