This dissertation argues that the Red Power Movement (1969–1973) was an architectural project for Indigenous sovereignty. Every protest involved the takeover of colonial architecture: frontier-era forts; Bureau of Indian Affairs offices; Department of Defense property; seemingly mundane governmental infrastructure; national iconography, including Mount Rushmore, Ellis Island; and the infamous Wounded Knee massacre site. Activists used takeovers as historiographical interventions to make colonial history contemporary again for the non-Indigenous public. Internally, takeovers functioned as intergenerational intertribal design laboratories in which activists debated and developed decolonial and Indigenous design principles. Uniting spatial and cultural modes of analysis, this dissertation examines the strategies activists used to design political transformations, weaponizing landscapes shaped by their oppressors against the state and creating new worlds within old architectural forms. Analyzing Indigenous sovereignty as an architectural project—recognizing activists as design historians, theorists, critics, and practitioners—this dissertation illuminates an overlooked history of decolonization through design in the United States.