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
European System of Central Banks banks that maintain separate currencies. European System of Central Banks The European System of Central Banks (ESCB) consists of the European Central Bank (ECB) and the national central banks (NCBs) of all 28 member states of the European Union (EU). The ESCB is not the monetary authority of the eurozone, because not all EU member states have joined the euro. That role is performed by the Eurosystem, which includes the national central banks of the 19 member states that have adopted the euro. The ESCB's objective is price stability throughout the European Union. Secondarily, the ESCB's goal is to improve