The most interesting place to visit outside the city are these caves in the rocky walls of the sandstone mountains at the confluence of the Ou river and the Mekong, some 25 kilometres upriver from Luang Prabang.
The caves are inhabited by thousands of Buddha statues, some allegedly more than 300 years old. Monks used to live in the caves, too. When Laos was still a monarchy, the caves were visited every year by the king. A small royal Wat is near the caves.