When we refer to Brussels, often, we are talking about the European Commission.
Housed in the Berlaymont building in the European quarters of the Belgian capital, the Commission is known as the EU's executive. That's in part because it is the only institution that can propose EU laws and policies which gives it considerable influence over the direction the bloc is taking.
Once the Council and lawmakers in parliament have approved the laws following inter-institutional negotiations, the Commission must then ensure that they are implemented and respected in all the member states.
That may mean taking them to court if they fail to do so and this is why the Commission is also known as the guardian of the EU Treaties.
The Commission is also responsible for preparing and proposing a draft budget for the EU based on what it thinks the priorities for the coming years should be.
All this work is being undertaken by a Commission President and a college of 27 Commissioners — one from each member state. Each has specific portfolios, similarly to ministers, that range from foreign affairs and migration and the economy, environment, agriculture and health among others.
Watch our video explainer in the player above.