While the fall of the Berlin Wall had broad economic, political and social impacts globally, it also had significant consequence for the local urban environment. In fact, the events of 9 November 1989 saw East Berlin and West Berlin, two halves of a single city that had ignored one another for the better part of 40 years, finally "in confrontation with one another". There was a belief in the city that after 40 years of division, the reunified city would be well placed to become a major metropolis. In the context of urban planning, in addition to a wealth of new opportunity and the symbolism of two former independent nations being re-joined, the reunification of Berlin presented numerous challenges. The city underwent massive redevelopment, involving the political, economic and cultural environment of both East and West Berlin. However, the "scar" left by the Wall, which ran directly through the very heart of the city had consequences for the urban environment that planning still needs to address. Despite planning efforts, significant disparity between East and West remain. The reunification of Berlin presented legal, political and technical challenges for the urban environment. The political division and physical separation of the city for more than 30 years saw the East and the West develop their own distinct urban forms, with many of these differences still visible to this day. East and West Berlin were directed by two separate political and urban agendas. East Berlin developed a mono-centric structure with lower level density and a functional mix in the city's core, while West Berlin was poly-centric in nature, with a high-density, multi-functional city center. The two political systems allocated funds to post-war reconstruction differently, based on political priorities, and this had consequences for the reunification of the city. West Berlin had received considerably more financial assistance for reconstruction and refurbishment. There was considerable disparity in the general condition of many of the buildings; at the time of reunification, East Berlin still contained many leveled areas, which were previous sites of destroyed buildings from World War II, as well as damaged buildings that had not been repaired. An immediate challenge facing the reunified city was the need for physical connectivity between the East and the West, specifically the organization of infrastructure. In the period following World War II, approximately half of the railway lines were removed in East Berlin. As urban planning in Germany is the responsibility of city government, the integration of East and West Berlin was in part complicated by the fact that the existing planning frameworks became obsolete with the fall of the Wall. Prior to the reunification of the city, the Land Use Plan of 1988 and General Development Plan of 1980 defined the spatial planning criteria for West and East Berlin, respectively.