This underground cave system was discovered by two local men in 1912—make that rediscovered, as one of the caves contained 42 human skeletons that had lain undisturbed for up to 7,000 years. The main cave system, Dan Yr Ogof (Welsh for "beneath the cave"), is an impressive natural wonder, particularly the Cathedral Cave with natural stone archways and a dramatic waterfall. The whole thing is pitched at kids, with "dramatic" piped music to "enhance" the atmosphere, and a park featuring life-size models of prehistoric creatures. There's also a petting zoo and playground. The caves are 17 miles southwest of Brecon.