Killing Fields, Phnom Penh
When you arrive at the airport you will be approached by taxi drivers who will try to rip you off. Remember, you can get a tuk tuk to take you anywhere you want for a full day for 15$, don't pay anything more, you will get offers to take you here or there for 30$ and on up, don't agree, shop around and when in doubt just head to your hotel and grab a tuk tuk for a much cheaper price. The taxi drivers know you are naive to the system fresh off your plane and will try to take advantage
Though some might find this visit interesting, I found it to be a waste of time. It is outside PP, you have to get there by motorbike (I paid 3 USD), then you get there and pay 2 USD, and all you get to see is a pile of skulls and some holes on the ground were mass tombs used to be.
I don't mean to be unrespectful with the many deaths and people that suffered here, but I think that if you wanna learn something about the topic, U better use those dollars in buying a good book on it...
Besides there is very few shade around and the sun makes the visit even harder...