Europe of population are Saint Petersburg, Madrid, Berlin and Rome, each having over 3 million residents. When considering the commuter belts or metropolitan areas, within the EU (for which comparable data is available) London covers the largest population, followed in order by Paris, Madrid, Barcelona, Berlin, the Ruhr area, Rome, Milan, Athens and Warsaw. "Europe" as a cultural concept is substantially derived from the shared heritage of the Roman Empire and its culture. The boundaries of Europe were historically understood as those of Christendom (or more specifically Latin Christendom), as established or defended throughout the medieval and early modern history of
Trade unions in Europe largest union confederation in Europe is the German Confederation of Trade Unions. Usually there are at least two national union confederations, one for academically educated and one for branches with lower education level. The largest Swedish union confederation is the blue-collar Swedish Trade Union Confederation ("Landsorganisationen", or LO). The LO has about 1.5 million members (including pensioners), which is a sixth of Sweden's population (Swedish blue-collar density in 2000 was 83% and in 2017 61%; the total density of blue-collar + white-collar employees in 2017 was 69%). Finland's equivalent is the Central Organisation of Finnish Trade Unions, with about one