Once the Khmer Rouge’s notorious S-21 prison, Tuol Sleng saw more than 17,000 men, women, and children interrogated and executed between 1976 and 1979. Today, the museum preserves its stark cells and haunting photographs, but many believe the victims’ spirits still linger. Visitors report ghostly cries, apparitions in the corridors, and an oppressive energy that weighs heavily on those who enter. Frequently featured in dark tourism documentaries and paranormal travel series, Tuol Sleng is regarded as one of Southeast Asia’s most chilling haunted sites.