Urban experimentation with sustainability has been gaining prominence in policy and academic discourses about urban transformations, spurring the creation of urban living laboratories and transition arenas. However, the academic literature has only begun examining why experimentation flourishes in particular cities, and why it conforms to place-specific styles. Meanwhile, the strategic niche management (SNM) tradition has extensively explored how protective spaces for experimentation emerge but has dealt only tangentially with why this happens in particular places. In this paper, we develop an approach for unpacking the formation of favourable environments for experimentation in specific places. We adopt an abductive research design to create a dialogue between distinct theoretical positions and one in-depth case study. Our case examines the formation of the Bristol energy scene, which hosts a variety of experimental initiatives concerning civic energy alternatives. Based on our findings, we refine the understanding of the processes shaping this experimental setting. There is value in characterising the 'genealogy' of experimental spaces and acknowledging their antecedents, path-dependencies and place-specificities. Efforts to foster urban transformation demand nuanced accounts of how places become experimental because they are not static backgrounds for experimentation.