National Showcaves Centre for Wales ( Dan yr Ogof )

National Showcaves Centre for Wales, is a 17-kilometre (11 mi) long cave system in south Wales, about 5 miles (8 km) north of Ystradgynlais and 15 miles (24 km) southwest of Brecon, in the Brecon Beacons National Park. It is the main feature of a show cave complex, which is claimed to be the largest in the United Kingdom and is a tourist attraction in Wales. The first section of the cave system is open to the public, but the extensive cave system beyond is scheduled as a national nature reserve and is open only to bona fide cavers. The bones of some 42 humans, as well as numerous animal bones, have been found in one of the nearby chambers of this cave system. The cave was first explored in 1912 by two local brothers, Edwin and Jeff Morgan, using candles and primitive equipment. Completely unsure of what they would discover, they armed themselves with a revolver. Edwin was the first to enter, as he was the smallest of the Morgan brothers.