Travel deep dive
Tuol Sleng and Choeung Ek: Cambodia's Genocide Memorials
For many visitors, Tuol Sleng and Choeung Ek are the most difficult stop on a Cambodia itinerary, and also one of the most important. Between 1975 and 1979, the Khmer Rouge regime emptied Cambodia's cities and ran the country as a forced-labour state; an estimated one and a half to two million people died from execution, starvation, forced labour and disease before the regime fell. Tuol Sleng, a former Phnom Penh high school converted into the regime's main security prison, and Choeung Ek, one of the sites where many of its prisoners were later taken, are preserved today as memorials. What follows is what each site actually contains and how to visit them, not a history of the wider period, which belongs elsewhere.
Updated 2026-08-15
Tuol Sleng: the School That Became S-21
Tuol Sleng was an ordinary high school until 1976, when the Khmer Rouge converted its four classroom buildings around a shared courtyard into S-21, the regime's main security prison for the Phnom Penh area. That ordinariness is still visible and is part of what makes the site affecting: the low concrete buildings, the open-air stairwells and the courtyard could belong to any school in the region, and the improvised cells inside — some built as narrow brick partitions within former classrooms, others simply the classroom itself lined with rows of iron bed frames — sit at odds with the setting around them.
The most extensive record the museum holds is photographic: the regime documented most prisoners on arrival, and several rooms are given over to these portraits, row after row of faces. It is the part of a visit most former visitors describe first afterward. A small number of prisoners are known to have survived the prison; the great majority did not. Most people find a self-guided walk with the audio guide takes around one and a half to two hours, and few move quickly through it.
Choeung Ek: the Memorial Stupa and the Grounds
Choeung Ek lies a slow tuk-tuk or car ride outside central Phnom Penh, on the site of a former orchard that the Khmer Rouge used as one of its execution grounds — the destination for many prisoners taken from S-21. It is one of many such sites found across the country, but the most visited, both for its proximity to the capital and its direct connection to Tuol Sleng.
A tall memorial stupa near the entrance holds skulls and bones recovered from the site's mass graves, arranged by age and sex as a forensic record rather than a display. Beyond it, a marked walking path circles the grounds — now grassed over and quiet, closer to a park than a former execution site to look at, with small signposts explaining what excavation found at each point along the way. Choeung Ek's audio guide, narrated in part with survivor testimony, is widely regarded as essential to understanding what the grounds show, since very little is left standing to explain itself.
Visiting Both Sites Together
Most visitors see Tuol Sleng first, since it gives the context that makes Choeung Ek's quieter grounds legible, then travel out to Choeung Ek afterward — the two combine comfortably into a single half-day with a tuk-tuk or car arranged for the return trip, since Choeung Ek itself is well outside the city and has no public transport connection back. Morning visits generally mean smaller crowds at Tuol Sleng, though neither site is ever heavily crowded in the way Phnom Penh's other landmarks can be.
Both sites are treated as memorials by Cambodians themselves, not as tourist attractions with a difficult backstory — many visitors are Cambodian, some visiting a place connected to their own family. Quiet, unhurried behaviour is expected throughout; photography is permitted in most areas of both sites but is restricted at some individual points, marked clearly by signage, and is worth following without argument. Casual or beach-style dress is out of place here in a way it is not elsewhere in the city.
Why These Sites Were Preserved
Both sites were kept deliberately rather than redeveloped, as a record for a country in which the period they document touched almost every family. Cambodia's own reckoning with the era continued for decades afterward: a UN-backed tribunal, the Extraordinary Chambers in the Courts of Cambodia, tried several of the regime's surviving senior leaders between the 2000s and 2010s, decades after the events themselves. Tuol Sleng and Choeung Ek predate that process and exist independently of it, functioning as the country's primary sites of public memory rather than as evidence tied to any single legal proceeding.