Esra Akcan’s September 22, 2016 lecture at the American Academy defines “openness” as a foundational modern value albeit prone to contradictions, and open architecture as the translation of the ethics of hospitality into architecture. It particularly focuses on a single street corner in Berlin, at Checkpoint Charlie, where the stories of an Italian architect, a Spanish architect collective, a Turkish guest worker, and a Kurdish refugee met during the time of Kreuzberg’s urban renewal in the 1980s. This case will be treated both as an example of the IBA’1984/87—a building exhibition of mostly social housing for which the Berlin Senate invited a large number of established and cutting-edge international architects—and as a prism of the notion of open architecture as collectivity.