A historical and theoretical account of the city of Berlin from the intertwined perspectives of architecture, environmental, and media studies. In 1945, having occupied German territory, Soviet troops made two strategic moves: they dismantled the Deutschlandsender III radio transmission tower, the single tallest structure at the time in Europe, and they seized the Haus des Rundfunks in West Berlin, a monumental building designed by Hans Poelzig. These moves were crucial both symbolically and technically, as together they sparked what would become a veritable radio war between the Eastern and Western blocs during the Cold War. In Radio-Activities, Alfredo Thiermann Riesco investigates this spatial conflict as he interrogates the political, technological, and environmental dimensions of architecture at a time when buildings began to interact with the remote transmission of information. By its very nature, the medium of radio promised to evaporate the intrinsic material aspect of architecture; in fact, it did no such thing. By way of transscalar analyses, Thiermann Riesco pays particular attention to Berlin’s buildings, walls, transmission towers, factories, research institutions, and territorial organizations during the Cold War period, which enabled the production, reproduction, and transmission of sonic-based content across the divide of the Iron Curtain. In doing so he reveals under researched continuities between politics, technology, media, and architecture, in the process reframing notions of national and transnational boundaries. A timely and fascinating study, Radio-Activities brilliantly interrogates the status and agency of buildings during a period—not unlike today’s—of increasingly hyperconnected, ubiquitous, and invisible modes of coexistence.