Using a variety of devices from visual displays, material objects, sensory engagements and embodied performance, museums select and narrate particular moments in history to an increasingly active audience. Thus far, focus on specific elements of museum design has eluded the altogether more pervasive, intangible and complex sensations designed, engineered, co-constituted and also arising unexpectedly from these sites: atmospheres. This article draws upon a particular museum experience -that of the prison museum -to interrogate how atmospheres are a key component of retelling the past. Here, the authors explore the production and consumption of what they term 'carceral atmospheres'. Focusing on two prison museums, the article explores how visitors unlock experiences of incarceration via the variety of atmospheric sensations calculated and provoked in these museum settings through visual/material manifestations and cues. The authors conclude that understanding atmospheric design is vital to gaining a deeper appreciation of how heritage sites function in the 21st century.