This monograph addresses mobility and migrations as contributing phenomena in shaping contemporary Europe after 1945, in connection with decolonisation and the creation of the European Community. The disappearing of the colonial empires caused a large movement of people (former colonizers as well as formerly colonized people) from the extra-European countries to the "Old continent"; while the European integration project encouraged the movement of the citizens within the Community. The book retraces how, in both cases, migrations and mobility impacted the way national communities, as well as the European one, have been defining themselves and their real and imaginary boundaries.