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
Slavery in medieval Europe an increasing number of black Africans. Between 1489 and 1497 almost 2,100 black slaves were shipped from Portugal to Valencia. By the end of the 15th century, Spain held the largest population of black Africans in Europe, with a small, but growing community of black ex-slaves. In the mid 16th century Spain imported up to 2,000 black African slaves annually through Portugal, and by 1565 most of Seville's 6,327 slaves (out of a total population of 85,538) were black Africans. Slavery () existed on the territory of present-day Romania from before the founding of the principalities of Moldavia and Wallachia