Most people have heard of Angkor Wat, the large temples in Cambodia. However, not many people make it to another Angkorian temple in southern Laos called Wat Phu. This huge ancient temple is still in ruins and waiting for restoration, but still unbelievably beautiful. The temple is built with multiple tiers, and as you ascend up the stairs surrounded by frangipani trees you get a sense of awe at the scope of the ancient architecture. At the top you will see an elephant carved into a rock and a large stone slab with a crocodile carved into it, reputed to once be used for human sacrifice. All in all, one of the best historical sites that Laos has to offer.
Many important parts of the ruins lay in the museum at the base of the site so don't miss this.