This paper makes a point on a hypothetical research about the origins of metropolitan thought referring both to a natural process and to the need of reorganizing the concept of city focusing on its dimension and function. The metropolitan area originates from the evolution of built-up areas cut off by free spaces - between cities and rural villages - which preserve their municipal administrative autonomy (urban continuum). Since then the standards to define metropolitan areas have undergone different alterations. Initially the Italian law intervenes by reorganizing competences among administrative levels, afterwards by promulgating special founding laws. What kind of phenomenon is it and how can it be handled at a juridical level? What are its implications?