The Tuol Sleng Genocide Museum in Phnom Penh, a former school, used to be one of the most brutal re-education camps in Cambodia, where thousands of people got killed and tortured. Most prisoners were then bought to the Killing Fields just outside of Phnom Penh.
A more cheerful sight is the Royal Palace, which is a stark contrast to Phnom Penh’s dusty streets with its manicured gardens and golden buildings. It is a beautiful complex with lots of impressive Khmer architecture to explore.
My favourite neighbourhood for exploring is the riverfront, which is lovely for a stroll, but also great to grab a bite to eat, enjoy a cold drink and visit some local markets, such as the old market in the old French quarter.
Street food can be found everywhere in Phnom Penh, as vendors have mobile kitchens attached to their motorbikes and so are able to prepare food anywhere they stop. It is delicious and really cheap where a meal often only costs $1.