Dan-yr-Ogof National Showcaves Centre for Wales

Brecon Beacons National Park

The limestone plateau of the southern Fforest Fawr is riddled with some of the largest and most complex cave systems in Britain. Most can only be visited by experienced cavers, but this set of three caves is well lit, spacious and easily accessible, even to children. The complex is just off the A4067, north of Abercraf.

The highlight of the 1.5-mile self-guided tour is the Cathedral Cave, a high-domed chamber with a lake fed by two waterfalls that pour from openings in the rock. Nearby is the Bone Cave, where 42 Bronze Age skeletons were discovered. Dan-yr-Ogof Cave, part of a 10-mile complex, has glistening limestone formations.

Somewhat at odds with the natural attractions are the plexiglas dinosaurs peeking through the trees, some of them locked in mortal combat, and a recreated Iron Age farm with mushroom-like huts. The admission fee covers other child-friendly draws, including a petting zoo and a shire-horse centre.

Beneath the hillside to the east lies the twisting maze of subterranean chambers known as Ogof Ffynnon Ddu (Cave of the Black Spring), the deepest and third-longest cave system in the UK (308m deep, with 30 miles of passages). This one is for expert potholers only, but you can explore it virtually at www.ogof.net.