The project focus on mobility related to one of the central element of every society: labour market. One of the reasons more frequently adduced at the base of the choice of emigrate is the research of a job. Many scholars have analysed migratory chains and professional specializations of ethnic groups , stressing as immigrants communities were able to conquer relevant places on the labour market. Therefore, the fact that immigrants were not secondary actors on the labour market stage is ascertained, and some studies point out as many foreign people could reach a prestigious position in the city of arrival . Pre-industrial cities and their labour market, in fact, seem to be quite open to foreigners: as many scholars have underlined , modern towns did not divide their inhabitants between citizens and not, but rather between stable and temporary inhabitants. This feature of openness is at the base of the strong circulation of women, men, wealth and knowledges between pre-industrial European countries. In all the major cities we can find foreigners communities, which are frequently well inserted in the local labour markets, to whose functioning they are an indispensable part. Migrant workers mobility traces therefore the lines of a working common space, an European Labour Market where women, men, wealth and knowledges move along, a common space kept together despite its differences and its largeness by the networks between different (and sometimes far) cities, built up and kept in time by its migrant inhabitants.