The European Central Bank is based in: 

The European Central Bank (ECB) is the central bank for the euro and administers monetary policy of the Eurozone, which consists of 19 EU member states and is one of the largest currency areas in the world. It is one of the world's most important central banks and is one of the seven institutions of the European Union (EU) listed in the Treaty on European Union (TEU). The capital stock of the bank is owned by the central banks of all 28 EU member states. The Treaty of Amsterdam established the bank in 1998, and it is headquartered in Frankfurt, Germany.