By the 1960s, quite different societies were developing in the two halves of Berlin, one under capitalist auspices and the other under communism. With West German Chancellor Willy Brandt’s Ostpolitik in the early 1970s, a series of treaties resulted in recognition of the GDR and easing of travel restrictions from west to east. Under GDR leader Erich Honecker, the modernity of ‘actually existing socialism’ was expressed in an energetic housing development programme, significant public buildings, and some leeway for cultural experimentation; yet the secret police or Stasi continued to expand, and the physical apparatus of the Wall was further refined. Divergent identities between East and West were evident not only in differing political ideologies, social profiles, and degrees of freedom, consumerism, and material well-being, but also in patterns of historical memorialisation. In the 1980s the economic and environmental decline of the GDR became ever more visible. Growing unrest culminated in challenges to communist rule and the opening of the Wall on 9 November 1989, and led to German reunification in October 1990.