The process of European monetary integration would have been longer but much less costly, had euro zone been created at least a decade later. Had Europeans decided to extend the period of functioning of the ERM mechanism with the 15% band (introduced in 1993), central banks might have been able to use the extended autonomy of monetary policy to cope with the unsustainable lending booms before the creation of the monetary union. This might have saved Europe from paying a very high cost of the twin bank and fiscal crises. Had the tightening of monetary policy turned out to be insufficient to cope with the unsustainable lending booms in several European countries, central banks could have earlier employed macroprudential policies as a second weapon of their stabilization policy. Had the euro zone been created at least a decade later, the experiences with the unsustainable lending booms would have forced Europeans to create monetary union with a better institutional setup.