While walking down the corridors of the Tuol Sleng Museum, with their checked tile floors and cream walls, it’s not hard to imagine the site’s simple origins as the Tuol Svay Prey High School. However, delving into former classrooms shatters any illusion of normalcy. A single rusty bed and a disturbingly gruesome black-and-white photo are all that adorn some rooms, but they stand as testament to the unthinkable horrors that happened here.