The wild mountains and hidden valleys of the Brecon Beacons have been recognised with an international award.
The area is one of the most important geological sites in Europe
An area called Fforest Fawr, whose rocks record 470m years of history, has been named a geopark, making it one of only 24 in Europe.
Geopark status recognises the geological significance of an area.
It is the UK's first national park to win geopark membership, and authority chief Christopher Gledhill said it recognised the "amazing" landscape.
The geological heritage of this stunning part of Wales, in the central beacons, will be protected and promoted by the United Nations Educational, Scientific and Cultural Organisation (Unesco) .
In part, Unesco chose to make Fforest Fawr a geopark because it contains evidence of ancient seas, caves and waterfalls - a landscape shaped by the last ice age.
Among the other sites in the geopark are Carreg Cennen Castle, the Welsh National Showcaves, the Black Mountain, Pen y Fan mountain, Craig-y-nos Country Park, Brecon Mountain Railway and the national park's reservoirs.
A spokeswoman for the Brecon Beacons National Park Authority, which applied for the membership, said geopark status would recognise and protect an area which is "blessed with one of the most geologically interesting landscapes in southern Britain".
She added: "The rocks within the western Brecon Beacons record 470 million years of geological history in some of the most outstanding scenery in the UK."
The authority's chief executive, Mr Gledhill, added: "This is fantastic news for the Brecon Beacons National Park and big news for Wales.
"I want to thank all those who worked so hard on this bid for so long - it has been a real team effort. Finally, this amazing landscape has been officially recognised as one of the most important geological landscapes in Europe."
The park authority said it hoped geopark membership would emulate the success of the other sites around the world that have seen a major increase in visitor numbers and the creation of hundreds of new jobs.
There are three other geoparks in Britain, two in England and one in Scotland.
The geopark was officially opened by former Labour leader Lord Kinnock.