Advances in digital technology spell the possibilities of conducting mobile modes of interaction across national boundaries, and in the process expose the participants to novel sensory experiences, giving rise to a new form of public culture. Understanding this phenomenon calls for a reconceptualization of "public space" and "ambience," as well as connecting the two concepts with each other. This pioneering study of the impact of media platforms on urban cultural life presents a theoretical analysis and a history of screens, followed by discussions of site-specific urban screen practices on five continents. There is also a substantial examination of the world's first real-time cross-cultural exchange via the networking of large public screens located in Melbourne and Seoul.