The paper revisits two decades of research on contestations of memory activism and efforts to decolonise the public space in postcolonial southernAfrica, insisting that social memory is primarily about contested claims to power. My earlier work primarily engaged with the historical staging of former colonial empire and postcolonial nationalist narrative through memorialization in statues and monuments and the built environment. More recently, my work has increasingly shift ed to include embodied and performative practices that subvert dominant narratives of nationalism and liberation. Artist-activists have (re-)created spaces, in which the meanings of remembrance as a fiercely contested process of past-based meaning production in the present are subverted through artistic interventions. I will explore questions relevant to the collaboration of artists, activists and researchers in art-based practices: How does the site and the dynamic situation in which the artist and the researcher work shape the co-production of multi-faceted knowledge? Which complex questions are raised for radical art, activism, and art-based research practices regarding collaboration and ethics? I unravel these questions through case studies from South Africa and Namibia, where artists, scholars and activists have come together inintersectional activism such as #RhodesMustFall and #ACurtFarewell. These campaigns to decolonise public space through removing colonialmonuments have linked mobilisation for the decolonisation of the public space with enduring and entangled structural violence, highlighting issues of racism, gender and sexuality, as perpetuated by coloniality.