This chapter addresses the concept of mnemonic landscapes in the example of the former penal colony in French Guiana, one of the most sprawling illustrations of the ways in which unintentional monumentality occurs in prominent historical sites. Mnemonic landscapes can be composed of ruins or ecologies or both; as Édouard Glissant theorized the Caribbean region: “our landscape is its own monument.” Mnemonic landscapes are particularly important sources of cultural memory because they memorialize willfully forgotten sites of state violence. The hauntings of these repressed histories nonetheless emerge from the land itself in material and spectral forms. Whether they are officially commemorated or ignored, sites of trauma and suffering resist practices of forgetting because they have a “mnemonic energy” (Assman) that asserts itself in unexpected and thus all the more effective and affective terms. The case of the penal colony is striking because of its size (covering several coastal islands in multiple clusters of buildings) and its unambiguous witnessing of a brutal history of incarceration. It also traces a transgeographical form of memory in that, while it is located in French Guiana, the penal colony is an apparatus of the French colonial government and one of several nodes along France’s “carceral archipelago,” as Foucault named it. In its state of ruins and encroaching vegetation, the site signifies the neglect and forgetting that has nonetheless been documented in the agent of memory under investigation in this study: the 1994 co-authored photo/essay Guyane: Traces-mémoires du bagne [French Guiana: Memory-traces of the Penal Colony] by Rodolphe Hammadi and Patrick Chamoiseau, a work scaffolded upon the mnemonic landscape poetically and visually.