Discussions on social movements in Asian cities are inseparable from the abundance of public rallies in the region. In this article, I look at the case of Thamrin‐Sudirman, the main thoroughfare in Jakarta, Indonesia, to uncover how physical urban spaces constituting part of the city as living systems broaden the reach of social movements’ agendas. The study involved continuous observation at rallies, interviews with social movement leaders and participants, and a look at simultaneous public rallies in various cities. This article analyzes the sites of public rallies as ‘megaphones’, based on the patterns of issues featured in the rallies, the groups participating, and the nodes and paths that they constructed. Two key dimensions of the megaphone are: (1) the symbolic and historical significance of the sites of rallies; (2) the relationship between the space and the media. Particular sites in cities become places where information is gathered, distributed and transferred through the media, facilitating a network among cities. This article concludes that cities are agents of political actions that amplify ideas and spread them across the globe. The urban centers’ megaphonic function results from the synergy between the public space in the built environment and the public sphere, and is reflective of the recentering of the city.