This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book shows how specific advantages given to cities, for instance trading and taxation rights in medieval times, had a clear influence on the economy of cities and through that, on population growth. It also shows how so-called interaction environments, places for personal encounters and for the exchange of persons, goods (including cultural ‘goods’ like music, theatre or museological productions), capital and information, are today scattered over the Randstad (together forming the Holland Cluster), while at the same time concentrated in the main cities, spilling over in ever larger areas, in particular in Amsterdam. The book concludes that the reputation of Dutch national spatial planning of being effective in containing urban sprawl is unwarranted, or at best only partly justified.