Joining a truly fascinating 18-point tour is the only way to see Vieng Xai's seven most important war-shelter cave complexes, set in beautiful gardens backed by fabulous karst scenery. A local guide unlocks each site while an audio guide gives a wealth of first-hand background information and historical context. The Kaysone Phomvihane Cave still has its air-circulation pump in working order and is the most memorable of the caves. Tours leave from the cave office at 9am and 1pm. If you want a tour outside of these two times, you'll have to pay a 50,000K surcharge per group.