For visitors, the city has become synonymous with the brutality of Pol Pot's regime: it's the place where what happened here is really laid bare for outsiders to see and try to understand. Pol Pot's Khmer Rouge came to power during a military coup in 1975, and attempted to bring about a Marxist revolution overnight. The army forcibly marched almost all of Phnom Penh's residents into the countryside: everyone was to work in the fields as part of a new classless society. But things didn't end there. Inspired by Mao's Great Leap Forward, and fearful of his imagined enemies, Pol Pot ordered the systematic extermination of some 2 million 'enemies' over a 3 year period: Vietnamese, intellectuals, anyone who had supported Lon Nol [Pot's immediate predecessor], foreign language speakers, doctors, lawyers, even children were killed in the name of the new regime.

People were taken to prisons around the country to be interrogated, sometimes for months, tortured until they agreed to produce 'confessions' and then were sent to the 'killing fields.' If they were lucky they were shot – if not, they were either decapitated or hit over the head with a blunt object, in order to preserve bullets.

At the height of the Khmer Rouge's regime, there were hundreds of prisons across the country,

but Phnom Penh's Tuol Sleng prison, or S21 as it was better known, was the central prison in the operations. It was run by a man called Duch, who is currently one of the few members of the regime standing trial for his crimes. Formerly a school, the site was converted into 4 prison blocks which were used to incarcerate and interrogate prisoners. The individual cells are so small one person could barely lie down, and the large cells held up to 40 people at any one time, shackled together by their ankles. The walls are covered with pictures of the victims – of 17,000 people brought here, only 7 survived.

Once a person's guilt had been 'proven', he or she was taken to Cheung El Killing Fields. Today it's a small and quiet field, birds singing in the background. This makes what happened here all the more astounding. The field is dominated by a 17 story stupa, which contains skulls, bones and clothing found when some of the pits here were excavated in 1980. The stupa serves as a delicate compromise: giving the victims the proper religious respect they deserve, whilst also showing the reality of what happened here. Wooden signs explain the different pits, what was found there, how the field operated. Most distressing is the tree against which soldiers used to kill babies by smashing their heads. Quite what kind of person, however afraid, could agree to do this, is simply beyond me.

So it was a difficult visit in some ways, but there is much more to Phnom Penh than its past. We also visited the Royal Palace, which still functions as the main royal residence today. It's a stunning complex, with a golden throne room and a silver pagoda with some 5000 silver floor tiles and a 90kg golden Buddha, dripping with diamonds. There's also a slightly creepy recreation of the royal coronation procession from 2004, complete with a muppet-esque waxwork model of the King himself. Bizarrely, it's made us want to visit Buckingham Palace next year – I doubt they'll have a Queen Elizabeth II Coronation muppet though.

And one of our favourite moments in the city came walking back from a day's sightseeing through the local park, at around 5pm. It was absolutely filled with people, enjoying the last of the sunshine after a hard day's work. Lots of old women danced along to loud pop music, led by energetic and very camp young men, people were playing badminton, going for a jog, or just enjoying a chat and a snack.