There's not a ton of sightseeing to do in Phnom Penh, but one of the must-see places in Cambodia's capital city is The Royal Palace. The Royal Palace is the official residence of Cambodia's king, and is situated near the Mekong River.
I didn't get a tour guide for my visit to the Palace, which I actually quite regret because I think I would have enjoyed my visit more if I had known more about what I was looking at. Nonetheless, it was a beautiful day and I enjoyed wandering the area and taking in the sights.
During my time in Cambodia I also visited two very large markets. The first one I visited is the Central Market. The Central Market has been around 1937, and is marked by a beautiful dome building. You can buy pretty much anything at this market, from clothes, to electronics, to food, to house goods. I didn't really need to buy anything, but I just wandered around for a bit to get a feel for the atmosphere.
I also went to Phnom Penh's other famous market, the Russian Market. This gigantic market is called the Russian Market because of the large amount of Soviets that visited in the 1980s. Inside it was SUPER hot and crowded with just about every kind of item you could ever want to buy. I didn't take any pictures here because it was ridiculously hot and didn't seem like the safest place to be walking around with my iphone in the open. Again, I didn't need to buy anything else because my backpack was already pretty full and heavy, so I just walked around the premises for a while to get a feel of the atmosphere.
If I had come to Cambodia with a larger bag, there is definitely stuff I could have bought for great prices at both of these markets. Unfortunately, when you're backpacking you only have a small amount of space in your bag, most of which was already occupied in mine from my shopping at the night market in Laos. Still, I'm glad I took the time to explore these notable locations in Phnom Penh.