Although Angkor Wat is the predominant attraction in Cambodia, Phnom Penh offers some worthwhile sites. If Angkor Wat represents the awe-inspiring Khmer golden ages, Phnom Penh has sobering memorials to its darkest periods.
If you only have one day in Phnom Penh, the following itinerary should be doable, if a bit packed.
1. Get up early in the morning and hire a tuktuk to take you to the first three sites, the most important of which is the "killing fields" or the Choeung Ek Genocidal Center. Although, there are various "killing fields" in Cambodia, the one in Phnom Penh is the most visited. There is a fee to enter and modest dress should be worn out of respect. The audio guide is included with your ticket.
Warning: This is a harrowing and devastating experience - as it should be for the horrors that happened during the reign of Pol Pot are unspeakable. Cambodians turned against other Cambodians in a genocide that wiped out almost two million of the population.
2. After the killing fields go to the infamous Tuol Sleng prison, which used to be a high school until it became a torture and interrogation center for the Khmer Rouge. There is a fee to enter, and an audio guide is provided. Again, this is a very bleak and soul-wrenching experience. There are blood stains still in the empty rooms.
I recommend visiting Tuol Sleng after the Killing Fields (even though technically, those who were imprisoned visited Tuol Sleng first and then were brought to the Killing Fields) because if you're like me there's only so much horror one can stomach. I thought the Killing Fields deserved more of my morning. Once I got to Tuol Sleng, I spent about an hour before I decided I had had enough for the day and needed something more uplifting.
3. After the sadness of the Killing Fields and Tuol Sleng, grab a cheap but satisfying lunch at the Russian Market, where life is bustling and noisy and somewhat restore your spirit. Do some light shopping too - everything from scarves to household items are for sale.
4. Get dropped off at the Royal Palace and you can dismiss your tuktuk driver for the day if you like, as the next two sites are within walking distance. There is a fee to enter and modest dress (arms and shoulders covered and no shorts) is required.
5. After exiting the Royal Palace turn left and walk down the riverfront, where there are many restaurants and clubs. After about 5-6 blocks, you will come upon a series of docks with cheap one-hour cruises ($5-$10). Time your cruise to catch the sun setting on the Mekong River. You can bring your own food and drink on board.
6. After the cruise, take some time strolling among the riverside pubs and neighborhoods. Drinks can be had for $1.50 and up. Relax and take in the view, do some people-watching and enjoy modern Cambodian life.