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 Central Bank to reach about €2,500 billons and is currently expected to last until at least end of 2018. The principal monetary policy tool of the European central bank is collateralised borrowing or repo agreements. These tools are also used by the United States Federal Reserve Bank, but the Fed does more direct purchasing of financial assets than its European counterpart. The collateral used by the ECB is typically high quality public and private sector debt. The criteria for determining "high quality" for public debt have been preconditions for membership in the European Union: total debt must not be too large in