The popular tourist attractions for Phrom Penh are the Shooting Range, the Killing Fields, the Genocide Museum, the Russian Market, and the Central market.  Does anyone see a common theme here? 
Death, negativity, and depressing activities. I decided to just do two the Russian market and the Genocide museum.  Of course, non-touristy attractions along the way such as the Ta Phrom Temple and a primary school where I spent sometime with hopscotch with the kids. 
Walking through Phrom Penh in daylight, it is a bit better than night time as there is action in daytime, but I still get an eerie feeling walking the streets. I try to rent a bike and of course it is unsuccessful.  The chances of me having a bike that works are very low on my trip.  The ones I tried did not have brakes and if you ever saw the traffic in Phrom Penh and the way people drive-you would say this is most likely a death sentence. 
 The streets feel full of real culture with many food stands, locals eating noodle soup, preparing local delicacies, and always the tuk tuks roaming the streets looking for customers.  My local interaction is not as strong as other places , but I connect with a few that are genuine and curious about my trip and background.  I also met the cutest little 3 year old who was half Chinese and half Cambodia-what a doll. 
The Tuol Sleng Genocide Musuem
As I have mentioned before, the Khmer rouge came in 1975 and wiped out over 2 million people in Cambodia. The site used to be a high school, but it was used as a Security prison during the regime. They have all the cells still in the same condition with a metal bed and torture chains.  They show the bars where they were tortured and forced to exercise outside.  They have thousands of faces(the photographs taken when first arriving to the prison) looking at you as you walk through.  Some look worried, anxious, petrified, sad, and confused. There are human skulls that they have lined up in cabinets and paintings depicting the torture and tragedy.  The stories that were posted by survivors were heart felt and made me feel such sadness for these people.  
As a human being that sincerely FEELS and is ALIVE, I had difficulty accepting these deaths and the absurdity of this whole regime. These were human beings, teachers, doctors, students, children just wiped out and tortured for absurd reasons.  After this, I spoke with a survivor who was selling his book.  Out of 17,000 imprisoned, there has been record of only 7 survivors.   I knew that I did not want to go to the killing fields as I had already been exposed to enough of the reality of this historical tragedy.  
Here is a description from Wikipedia as it has detail of their routine in prison:
Life in the prison
 
Upon arrival at the prison, prisoners were photographed and required  to give detailed autobiographies, beginning with their childhood and  ending with their arrest. After that, they were forced to strip to their  underwear, and their possessions were confiscated. The prisoners were  then taken to their cells. Those taken to the smaller cells were  shackled to the walls or the concrete floor. Those who were held in the  large mass cells were collectively shackled to long pieces of iron bar.  The shackles were fixed to alternating bars; the prisoners slept with  their heads in opposite directions. They slept on the floor without  mats, mosquito nets, or blankets. They were forbidden to talk to each  other.
[1]The day in the prison began at 4:30 a.m. when prisoners were ordered  to strip for inspection. The guards checked to see if the shackles were  loose or if the prisoners had hidden objects they could use to commit  suicide. Over the years, several prisoners managed to kill themselves,  so the guards were very careful in checking the shackles and cells. The  prisoners received four small spoonfuls of rice porridge and watery soup  of leaves twice a day. Drinking water without asking the guards for  permission resulted in serious beatings. The inmates were hosed down  every four days.
[1]The prison had very strict regulations, and severe beatings were  inflicted upon any prisoner who tried to disobey. Almost every action  had to be approved by one of the prison's guards. They were sometimes  forced to eat human feces and drink human urine.
The unhygienic living conditions in the prison caused 
skin diseases, 
lice, 
rashes, 
ringworm  and other ailments. The prison's medical staffs were untrained and  offered treatment only to sustain prisoners’ lives after they had been  injured during interrogation. When prisoners were taken from one place  to another for interrogation, their faces were covered. Guards and  prisoners were not allowed to converse. Moreover, within the prison,  people who were in different groups were not allowed to have contact  with one another.
Torture and extermination
 
 
 
Waterboard displayed at Tuol Sleng. Prisoners' legs were shackled to the  bar on the right, their wrists were restrained to the brackets on the  left and water was poured over their face using the blue watering can.
 
 
Photos of the victims of the Khmer Rouge line the walls
 
 
Cabinets filled with human skulls
Most prisoners at S-21 were held there for two to three months.  However, several high-ranking Khmer Rouge cadres were held longer.  Within two or three days after they were brought to S-21, all prisoners  were taken for interrogation.
[1]  The torture system at Tuol Sleng was designed to make prisoners confess  to whatever crimes they were charged with by their captors. Prisoners  were routinely beaten and tortured with electric shocks, searing hot  metal instruments and hanging, as well as through the use of various  other devices. Some prisoners were cut with knives or suffocated with  plastic bags. Other methods for generating confessions included pulling  out fingernails while pouring alcohol on the wounds, holding prisoners’  heads under water, and the use of the 
waterboarding  technique (see picture). Females were sometimes raped by the  interrogators, even though sexual abuse was against Democratic Kampuchea  (DK) policy. The perpetrators who were found out were executed.
[1]  Although many prisoners died from this kind of abuse, killing them  outright was discouraged, since the Khmer Rouge needed their  confessions. The "Medical Unit" at Tuol Sleng, however, did kill at  least 100 prisoners by bleeding them to death.
[4]In their confessions, the prisoners were asked to describe their  personal background. If they were party members, they had to say when  they joined the revolution and describe their work assignments in DK.  Then the prisoners would relate their supposed treasonous activities in  chronological order. The third section of the confession text described  prisoners’ thwarted conspiracies and supposed treasonous conversations.  At the end, the confessions would list a string of traitors who were the  prisoners’ friends, colleagues, or acquaintances. Some lists contained  over a hundred names. People whose names were in the confession list  were often called in for interrogation.
[1]Typical confessions ran into thousands of words in which the prisoner  would interweave true events in their lives with imaginary accounts of  their espionage activities for the 
CIA, the 
KGB, or 
Vietnam. The confession of 
Hu Nim ended with the words "I am not a human being, I'm an animal". A young Englishman named 
John Dawson Dewhirst  who was arrested in August 1978 claimed to have joined the CIA at age  12 upon his father receiving a substantial bribe from a work colleague,  also an agent. Physical torture was combined with sleep deprivation and  deliberate neglect of the prisoners. The torture implements are on  display in the museum. It is believed that the vast majority of  prisoners were innocent of the charges against them and that the torture  produced false confessions.
For the first year of S-21’s existence, corpses were buried near the  prison. However, by the end of 1976, cadres ran out of burial spaces,  the prisoner and their family were taken to the 
Choeung Ek  extermination centre, fifteen kilometers from Phnom Penh. There, they  were killed by being battered with iron bars, pickaxes, machetes and  many other makeshift weapons owing to the scarcity, and subsequent price  of ammunition. After the prisoners were executed, the soldiers who had  accompanied them from S-21 buried them in graves that held as few as 6  and as many as 100 bodies.