Institutional seats of the European Union are based in Luxembourg City along with the European Investment Bank. The Economic and Social Committee and the Committee of the Regions are entirely based in Brussels while the European Central Bank is based in Frankfurt and Europol is the only agency to have its seat fixed by the treaties, in The Hague. Separately, the Treaty of Nice establishes Brussels as the venue for all formal summits of the European Council after 2004. However some extraordinary sessions are sometimes held outside the city. The European Council's seat is however fixed by a declaration rather than a protocol, meaning it is
President of the European Union the executive branch of the European Union, takes part in the G7 and other international summits as well. All four offices have been described as the President of Europe, however, none can be seen to be analogous to the President of the United States (who is both head of state and head of government). Imperfect comparisons with other political system have attempted to explain the complex nature of the European institutions. As each institution has its own leader, it has been suggested that the terms "Speaker" of the European Parliament, "Governor" of the European Central Bank, "Chairman" of the Council