Plain of Jars
Concierge.com's insider take:
Southeast Asia's most enigmatic tourist attraction, the Plain of Jars is named for the hundreds of enormous stone containers scattered over a few square miles there. Historians are baffled as to their origin and purpose. One theory is that they were created by an Iron Age civilization, possibly as funerary urns for cremated remains. The jars are not made from local stone and weigh several tons, so it's a mystery as to how they were transported here. You can hire a car and guide at nearby Phonsavan, the provincial seat. In the countryside, do not stray from designated paths, because there's a risk of encountering unexploded ordnance.