Phnom Penh: The Killing Fields and S-21
Tuol Sleng Genocide Museum (S-21) and the Choeung Ek Killing Fields are not attractions. They are the two central sites of the Cambodian genocide, and this page treats them with the gravity that requires: what happened, what to expect, and how to visit respectfully. There is no listicle version of this history.
What happened, stated plainly
From 17 April 1975 to early January 1979, the Khmer Rouge, formally Democratic Kampuchea under Pol Pot, ruled Cambodia. An estimated 1.7 to 2.2 million people died during those years, roughly a quarter of the country’s population, from execution, starvation under forced agrarian policy, forced labor, and disease. The regime fell when Vietnamese forces took Phnom Penh in early January 1979. Any number you see quoted for the death toll should be treated as an estimate within that range, not a precise figure; the true count will never be known exactly.
Tuol Sleng Genocide Museum (S-21)
Tuol Sleng was a Phnom Penh high school before the Khmer Rouge converted it into Security Prison 21, the regime’s central secret detention and interrogation center, in 1975. An estimated 14,000 to 20,000 people were held there over the following four years; almost all were killed, and only around 12 are known to have survived. It has operated as a museum since 1980, preserving cells, restraints, and a photographic archive the regime itself compiled of most prisoners.
It is open daily 8am-5pm. Admission is about $5 for adults, $3 for youth, and the $5 audio guide, available in 11 languages, is genuinely worth adding, it structures a visit that would otherwise be overwhelming. Tickets and information are available through the official Tuol Sleng site ; this is not a site to book through a third-party tour affiliate. The material is heavy and graphic. Go with the intent to understand, not to collect an experience.
Choeung Ek Killing Fields
Choeung Ek sits about 15km south of central Phnom Penh, roughly 30-45 minutes by tuk-tuk, and was the execution and burial site for prisoners transferred from S-21. The memorial stupa holds more than 5,000 skulls recovered from the site’s mass graves; of 129 graves identified, many remain unexcavated by deliberate policy, out of respect for the dead. The Killing Tree, where infants were killed against its base, is among the site’s most difficult features. Bone and cloth fragments still surface seasonally after rain; staff collect them as part of ongoing site care.
It is open daily 7:30am-5:30pm. Admission is about $6, including an audio guide that carries survivor testimony and is essential to a visit here, most of the site’s context comes from the narration rather than signage. Tickets are sold at the gate; there is no affiliate or third-party booking route for Choeung Ek, and none is needed.
Visiting both sites
The commonly recommended and most respectful order is Tuol Sleng first, then Choeung Ek, following the chronological path a prisoner would have taken from detention to execution. Budget three to four hours total for both. Dress modestly, shoulders and knees covered, as you would at any memorial. Photography is restricted in parts of Tuol Sleng out of respect for what the rooms document; follow posted signage at both sites. Most visitors find engaging with both sites in a single sitting, rather than splitting them across separate days, keeps the history connected rather than diluted. Don’t schedule anything upbeat immediately afterward.
Beyond the memorial sites
Phnom Penh’s Royal Palace, National Museum and riverside sit apart from this history geographically but not entirely from it in spirit, the city carries both openly. For the fuller city context, see our Phnom Penh guide , and for a day-by-day plan that gives these two sites their own sober half-day, our 3-day itinerary .