The close relationship between architecture and ideology is manifested most clearly in ideologically divided territories. The role of architecture as a projection screen for ideological messages is exemplified by East and West Berlin between 1945 and 1989. In both parts of the city, highly symbolic state, residential, and cultural buildings were erected and existing buildings were brought into line with ideology. As part of the exhibition Between Walls and Windows. Architecture and Ideology at Haus der Kulturen der Welt (HKW), this contribution seeked to open the ideas from the initiative 0150 Initiative Weltkulturerbe Doppeltes Berlin to a wider public. The Initiative Weltkulturerbe Doppeltes Berlin considered the mirrorable representative architectures built in East and West Berlin between 1945 and 1989 to be unique and aimed at promoting them as UNESCO World Cultural Heritage, being symptomatic of the divided Berlin. The Congress Hall of HKW, where the exhibition took place, has also a counterpart “on the other side”: the Congress Hall at Alexanderplatz. In the exhibition, a list of the double architectures was shown, which formulated the official public demand to have them listed as World Heritage Sites. The visitors were invited to become part of the initiative, to contribute material via the initiative office, which was set up at the Congress Hall for the duration of the exhibition, or to suggest further parallel architectures.