One of the arresting images in Michel Serres\'s Rome: The Book of Foundations is the idea that history is \”a knot of different times\”—a knot rendered visible by the tangible traces of past civilizations. The knot of which Serres speaks applies as readily to the stratigraphic realities of Roman urban space as to the composite aesthetics of 18th-century ruin pictures or Auguste Rodin\'s 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 a template for the Sublime to a 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 from the Hypnerotomachia Poliphili to antiquarian treatises. We will then consider how the cult of the ruin has shaped 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. Readings by Arnaldo Momigliano, Alois Riegl, Walter Benjamin, Michel Foucault, Manfredo Tafuri and Anthony Vidler among others.