Going to the killing fields was one of the most intense things I've ever done. The killing fields are where Pol Pot brought numerous cambodians for massacre for being opposed to the communist revolution and for other reasons as stupid as knowing a foreign language or wearing eyeglasses. His fascination with communism and marxist economics and his ruthlessness resulted in deaths of up to 3 million of his own people. A real tragedy was a loss of many of the educated, intelligent and talented people from the cambodian bloodlines by his killing of professors, doctors, dancers, and musicians. Pol Pot also tragically ordered destruction of many temples in Ankor and other religious artifacts and libraries.
The killing fields were a mass grave where around 17,000 people were buried. There is a temple where 8,000 skulls are held, arranged by age and sex. You can still see bones and clothes remaining on the ground from the killings. It is incredible.
Every Cambodian was affected in some negative way by Pol Pot and the Khmer Rouge. Everyone has had a family member killed or tortured by this regime. The most unbelievable thing is no one has ever been brought to justice from this brutal period.
S21 is probably even more difficult to take than the killing fields. It was a school turned into a prison where the Khmer Rouge kept "political" prisoners for torture and "reprogramming". Everything about S21 has been left intact since the Vietnamese "liberated" it during their invasion of Cambodia in 1979. There are several paintings on what life was like at the prison that one of the only seven survivors did, and these are displayed on the walls. They are amatuerish, but powerful. It is really overwhelming and hard to stomach.
There are also photos displayed of all the prisoners of S21displayed by sex and age. There was a family there that had a picture of their father, and they were looking through the pictures to try to find him. He has been missing since he was abducted by the Khmer Rouge in the war. It was unbelievable. It is amazing that these horrors took place, and in S21 you get just a little too close to it all.