ABSTRACT This paper explores the role of urban grassroot movements in the social configuration of contentious heritage and multiple temporalities and political articulations of heritage defense activism. Using the case study method, the paper traces the genealogy of one urban movement in defense of socialist modernist heritage in contemporary Montenegro, shedding light on the process of slow political recognition as opposed to the wide and rampant repertoire of urban contention and socio-cultural appropriation. Focusing on the events following the announcement of the construction of the 12-floor skyscraper (colloquially dubbed “the Monster”) in the immediate proximity of the iconic modernist Hotel Podgorica, the paper theorizes the capacity of urban activism in the contemporary post-socialist city to activate heritage dynamics and leverage urban knowledge as a tool of cultural control. Relying on a multi-method approach including participatory observations, interviews, urban and critical discourse analysis, and the archival research, this paper provides a multi-perspectival analysis of the complex interactions between contentious heritage, grassroot movements and political performativity in the post-socialist city. The results shed light on the evolving role of citizenship in urban development, signaling a paradigm shift towards engaged architecture and emancipatory urban activism as mechanisms for mitigating institutional inefficiencies and political performativity.