The metropolitan area is defined as an association on the basis of a voluntary partnership between urban and rural localities, where collaboration relations are established at different levels. The level of influence of the metropolitan area is established depending on the territory it organizes as a regional, national or international metropolis. As a result of the researches carried out, (inclusively in the DEMOS project) the Metropolitan Area of Bucharest (MAB) may include 61 administrative units within a radius of 50 km around the capital. In comparison to other capitals and metropolitan areas from Central and Eastern Europe (Berlin, Budapest, Prague, Warsaw), Bucharest occupies the fifth rank in terms of number of population and square kilometres, but it is ranking the first in terms of density (inhabitants/square kilometre), with 1266 inhabitants/ sq. km, in comparison to the second ranking city – Warsaw – having only 638 inhabitants/sq. km. This fact makes a strong argument for developing a metropolitan area in Bucharest.