Architecture in the twentieth century, more than any other period in history, embodies the very idea of innovation in building. Its innovation embraces both the continued refinement of proven techniques as well as the introduction of new technologies – as often as not dependent on the logic of industrialised production which in itself would come to revolutionise the entire construction sector. How do we recapture the diversity and complexity of the century’s construction systems? How do we retain the evidence of its architectural and technical history? This study, while not claiming to be exhaustive in its treatment, explores the specifics of the era’s more emblematic industrialised and prefabricated systems, and analyses the problems of architectural conservation that ensue. Ultimately, the architecture of the recent past, often synonymous with mass production and the heritage of the ordinary, demands a rethink of the concepts and common practices that inform heritage conservation in our time.