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
Currencies of the European Union Currencies of the European Union There are eleven currencies of the European Union used officially by member states. The euro accounts for the majority of the member states with the remainder operating independent monetary policies. Those European Union states that have adopted it are known as the eurozone and share the European Central Bank (ECB). The ECB and the national central banks of all EU countries, including those who operate an independent currency, are part of the European System of Central Banks. The euro is the result of the European Union's project for economic and monetary union which came fully