A Complete Guide to S21 and CHOEUNG EK – Cambodia’s Killing Fields

Beneath Cambodia’s serene tropical paradise, with its beautiful beaches, ancient ruins and relaxed backpacker vibes, lies a dark and tragic part of its recent history, and some of the most popular tourist sites in Phnom Penh serve as reminders of this.  

From 1975 to 1979 Cambodia was ruled by a brutal communist regime, the Khmer Rouge, which committed countless atrocities and that will make your skin crawl. In the real world, it’s rarely appropriate to denounce any group of people as ‘evil’, but if it is, it would be when describing this regime.

The Tuol Sleng Museum (S21) and Choeung Ek Genocidal Center are 2 sites in Phnom Penh used by the Khmer Rouge to imprison, torture and execute thousands of people. Visiting these sites is a confronting and tear-jerking experience.

So, why visit such disturbing places? The Khmer Rouge regime had a major impact on Cambodia’s modern history in ways that are still felt today, and is a harsh reminder of unchecked power mixed with radical ideology.  In the same way that visiting places like Auschwitz offer powerful lessons on humanity, so do S21 and Choeung Ek. 

Visiting them is encouraged by the Cambodian government, and if you’re going to travel Cambodia and enjoy everything it has to offer, it’s important to also learn about this major event that still hangs over it.   

In this guide, I’ve provided you with everything you need to know in thise complete guide to visiting Tuol Sleng (S21) and Choeung Ek.

Table of Contents

Background - The Brutal Regime of the Khmer Rouge

The Khmer Rouge (rouge being French for ‘red’ –  the symbolic colour of communism) were a communist militant group which, supported by North Vietnam, grew their forces while hiding in the jungles of eastern Cambodia. 

During the Vietnam War the US bombed Cambodia heavily in an attempt to stop their development, but this only pissed off the locals who would then go and join the group, making them even stronger.  

The Khmer Rouge, led by Pol Pot (a name you might have heard in the same sentence as Hitler or Stalin), took over the countryside before the capital finally fell in 1975. In their efforts to turn Cambodia into a classless, agrarian utopia, they immediately started the process of ‘social engineering’ and a rapid reorganisation of its entire society. 

They ordered the mass evacuation of the cities, who’s residents were seen as ‘upper class’ and forced everyone into collective farms, where they were all to live equally as farmers.

The regime arrested, tortured and executed anyone who they considered enemies to their new paradise. This included:

  • ‘Intellectuals’ – meaning doctors, scientists, teachers, engineers, lawyers; really anyone who wasn’t a farmer or a soldier.  There were even instances in which people who wore eyeglasses were considered ‘educated’ and therefore killed. 
  • Anyone with ties to any former Cambodian government. 
  • Anyone who wasn’t ethnically Cambodian.
  • Anyone who practised a religion.
  • ‘Economic Saboteurs’  – which meant people who had lived in cities and therefore didn’t have farming skills. 


Over time, their paranoia grew out of control and this list began to include many of its own members as the regime started to eat itself alive. Their insane policies seem almost comical, if it wasn’t for the very real cost of human lives. 

Unsurprisingly, these changes led to mass famine, a lack of medical supplies & basic services, and all around economic collapse. Over their short 4 year reign, the Khmer Rouge caused the death of 25% of Cambodia’s population, around 2 million people. 

Despite North Vietnam (which was now unified Vietnam) being their biggest supporter during their rise, relations had turned sour as the rest of South-east Asia were coming to realise how insane these people actually were, and this would be the Regime’s undoing. 

In April 1978, the Khmer Rouge launched a small incursion into southern Vietnam in which they tortured and massacred a village of over 3000 people, including the children. This would ultimately lead to Vietnam launching a full-scale invasion of Cambodia.

The Vietnamese won decisively, and took Phnom Penh within a month. They’d remain in Cambodia for some time and attempt to set up a new, pro-Vietnamese government. The Khmer Rouge appealed to the UN for help, and the US & other western nations actually supported their case, simply out of spite for Vietnam. It was thanks to the Soviet Union that their appeal didn’t go anywhere. 

Unsurprisingly, the new Cambodian government struggled to rebuild their society on account of their entire educated population being executed, an issue which still impacts the country to this day.  

You’d be forgiven for thinking that the Khmer Rouge leaders would be immediately arrested and tried for crimes against humanity, but this wasn’t the case. Most of the regime’s top officials fled into Thailand, they held their seat in the UN for years following, and there was no accountability for decades. A tribunal ran from 2006 to 2022 but only led to 3 convictions. Most of them have now died of old age.

Tuol Sleng Museum (S21)

Tuol Sleng, Cambodia

About

Previously a highschool, this site, which was dubbed Security Prison 21 (S21), was one of between 150 and 196 (no one knows for sure) prisons & torture centres operated by the Khmer Rouge during their regime. 

The school became surrounded by electrified barbed-wire, the windows were covered by bars, and the classrooms were turned into prison cells and torture chambers. 

Anyone who met one of the above-mentioned categories, and therefore deemed an enemy to the new communist utopia, were arrested and imprisoned at S21. Here they would be tortured and forced to give up the names of family members and friends, who would then suffer the same fate.  

During the Khmer Rouge’s 4 year reign, an estimated 20,000 people were held here, of which only 7 survived. The rest were sent to Choeung Ek to be executed en masse

After Phnom Penh was liberated by the Vietnamese Army in 1979, S21 was immediately turned into a museum and has been open ever since.  

In 2010 the prison’s chief, Kang Kek Lew, became one of the few members of the regime actually convicted for their crimes.

What to expect

Visiting the Tuol Sleng Museum is an uncomfortable and confronting experience.

After purchasing your ticket at the entrance, you can begin exploring the grounds. There are 4 main buildings that make up the old school, with each exhibiting something a little different. 

The rooms in building A are maintained exactly as they were when S21 still operated, complete with the old metal bed frame which the prisoner was chained to. Building B is a gallery, with the walls covered in countless black and white photographs of those imprisoned here, taken by the guards upon their arrival. 

The rooms in building C were subdivided with planks of wood, giving the prisoners here barely enough room to lie down, and are now maintained exactly as they were. Lastly in building D, you’ll find a display of the various torture devices used on the prisoners.  

Currently, between 2:30 to 3pm on weekdays, the museum holds a ‘survivor’s testimony’, in which one of the 7 survivors tells his story.

Costs | $5 (includes audio guide)

Opening Hours | 8am to 5:30pm

How to get there

Tuol Sleng Museum is located in downtown Phnom Penh and is easy to reach. 

Depending on where you’re staying, you may be able to walk there. If not, a tuk tuk should only set you back a few dollars. 

Or read our below section on tours to learn more about a cheap shuttle bus that will take you to both sites for $15. 

The barbed wired doors of Tuol Sleng in Cambodia
The former classrooms and cells of Tuol Sleng in Cambodia

Choeung Ek (Killing Field)

About

After victims were imprisoned and tortured at S21, they would then be transported in the back of trucks to a site outside the city. In much the same way that the concentration camps in Nazi Germany were kept secret from the general public, the Khmer Rouge attempted to to do the same with their mass genocide.

Choeung Ek, formerly a peaceful orchid just outside of Phnom Penh, became one of almost 300 ‘killing fields’ across the country, where the Regime would execute people en masse

After the Khmer Rouge were ousted by the Vietnamese in 1979, and the horrors of their regime fully came to light, the bodies of almost 9000 people were found buried here in mass graves. 

Most of those bodies, which included children, were found hand-tied and blindfolded. To save bullets, the victims, which included children, were killed using hand-held weapons, like pickaxes.

What to expect

Being the site where so many were brutally executed, visiting Choeung Ek is arguably even more confronting than Tuol Sleng Museum. 

Upon entering, the first thing you’ll see is the central Memorial Stupa, a Buddhist monument which displays the skulls & bones of around 5000 of the victims who were dug up at this site. 

You’re then free to explore the grounds of this former killing field, and see the many exhumed massive grounds, some of which still contain human bones. After this, there’s also a museum. It’s not very big, but it does provide an insight into the Khmer Rouge, including attempts to convict those responsible for places like this. 

Costs | $6

Opening Hours | 8am to 5pm

How to get there

Choeung Ek is located further away, about 17 km south of the city centre.

Hiring a tuk-tuk driver to take you there and back should cost you around $10, but you may want to arrange to visit both Choeung Ek and S21 in the same trip. 

The most practical way to combine both sites is to book the shuttle bus, which runs twice a day and will take you to both sites for $15. Learn more about this and other tours below. 

The skulls of the victims at Choeung Ek, Cambodia
The exhumed mass graves of Choeung Ek in Cambodia

Tours

S21 and Choeung Ek are not located some distance from each other, so the most practical way to visit them both is with a booked tour. 

For $20 to $30 you can book a full tour which covers:

  • Pick up and drop off to your hotel. 
  • Entry to both sites
  • Local guide
  • Bottled water

Check out S21 & Choeung Ek tours here.

Alternatively, there’s also a hop-on/hop-off bus service that runs twice a day, which will take you to both sites for only around $15, which you can find here.

Where to stay

Whether you’re looking for fancy hotels or cheap backpacker hostels, Phnom Penh is full of amazing places to stay. 

Hotels

From budget hotels to 5-star resorts, Phnom Penh has private rooms to suit whatever style of travel you’re looking for. 

Book | Check out Phnom Penh’s range of hotels here.

Hostels

Cambodia is a backpacker hotspot, and has no shortage of cheap hostels. 

If you’re seeking a place that’s lively and social, then I’d recommend you check out Mad Monkey Hostel. They have newly built, high quality rooms (including private rooms), a great common area and host social events multiple days a week.  

Book | Check out Mad Monkey and other hostels in Phnom Penh here.

Tips

Dress Code | As with any religious or commemorative site in Cambodia, it’s expected that you wear appropriate clothing, which requires your legs and arms to be covered. 

Use the audio guides | A lot of the information at these sites is more visual than informative. Using the audio guide, which comes included with your entry ticket, is a great way to gain a deeper insight into what took place here. 

Bring Water | As with almost any activity in the hot tropical climate of Cambodia, it’s advisable to bring bottled water. You’re going to be doing a lot of walking, which at Choeung Ek will also be outdoors.

Use the shuttle bus | The above-mentioned hop-on/hop-off shuttle bus is by far the cheapest way to arrange transportation to both sites, less than hiring a tuk-tuk driver to take you to both and back.

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