Where the Nam Ou (Ou River) and Mekong River meet at Ban Pak Ou, two famous caves in the limestone cliff on the west bank of the river are crammed with myriad Buddha images. In the lower cave a group of larger Buddhas is silhouetted against the stunning riverine backdrop. The upper cave is a five-minute climb up steps and tucked away 50 meter into the rock face. The caves are 25 km to the north of Luang Prabang, or two hours upstream by long-tail boat.