The Ruin Aesthetic: Episodes in the History of an Architectural Idea One of the most arresting images in Michel Serres\'s Rome: The Book of Foundations is the idea that history is \”a knot of different times\” — a knot most visibly reified by the tangible traces of past civilizations. Serress knot speaks as readily to the stratigraphic realities of Roman urban space as to the composite aesthetics of eighteenth-century ruin pictures or Auguste Rodins Symbolist recasting of Medieval church portals. Artifacts, fragments, vestiges, rubble, debris, detritus,wreckage: all this has prompted a venerable body of writings and objects that work the metaphor of ruin into anything from template for the Sublime to mechanism for iconoclastic violence. We will begin by thinking about architecture and the vision of the past in the early modern period, considering a range of examples such as the Hypnerotomachia Poliphili, Nicolas Poussin\'s Et in Arcadia Ego, and the plates of antiquarian treatises. We will then consider how the cult of the ruin has shaped notions of nostalgia and dystopia in modern contexts. Examples might include the Surrealist discovery of the broken column house at the Desert de Retz, Le Corbusier\'s apprehension of columns segments from the north facade of the Parthenon, Albert Speer\'s ruin theory of architecture, the Heideggerian concept of Ruinanz and the reflection of absence in the National September 11 Memorial. Writings by Arnaldo Momigliano, Alois Riegl, Walter Benjamin, Michel Foucault, Manfredo Tafuri and Anthony Vidler among others will be crucial to address.