The night sky above the Brecon Beacons National Park has been granted special protection.
It has become Wales' first and only the fifth destination in the world to be granted the status of an international dark sky reserve.
The park society and the national park authority began their bid in 2011.
Jim Wilson, Chair of Brecon Beacons Park Society, said it recognised the area as one of the best places in Europe "to truly see dark skies".
The park joins Mont Megantic in Quebec, Canada; Exmoor National Park in south west England; Aoraki Mackenzie in New Zealand; and NambiRand Nature Reserve in Namibia with the status.
The status means the night-sky is protected and lighting controls are in place to prevent light pollution.
The national park said it already possessed some of the UK's darkest skies, which was ideal for stargazing.
Officials claimed that on a clear night above the Beacons people could see the Milky Way, as well as numerous constellations, bright nebulas and even meteor showers.
Julia James, chair of Brecon Beacons National Park Authority, said attaining the status was a massive boost for the entire area.
She said it would bring many environmental, wildlife, economic, tourism and wellbeing benefits.
To get through the application process local astronomers conducted a survey to assess the levels of light pollution, and lighting engineers audited the existing external lighting in the national park.
Information leaflets and letters were distributed to residents living in the 'core zone' to help them understand the simple measures they could take, such as tilting outdoor security lights downwards instead of up, that could make difference to how dark the night sky appears.
Local communities supported the bid, with residents in Talybont-on-Usk holding their own Star Party and organising a community light switch off.
Martin Morgan-Taylor, board member of the International Dark-Sky Association, the US based organisation which awards the status, said the gradual loss of the view of the night sky was a loss of part of culture.
"Whilst no-one wants all the lights to be switched off, we can improve the lighting we use in towns and cities.
"However, the best views of the night sky come from places such as the Brecon Beacons, who have dedicated themselves to protecting and restoring the night sky for all to enjoy."
Jim Wilson, chairman of Brecon Beacons Park Society, thanked all those who had taken part in the project, saying it recognised the park as one of the best places in Europe to see truly dark skies.
Environment Minister John Griffiths called the accreditation a "massive coup".
He said: "It shows the level of commitment here in Wales to tackling climate change and improving peoples' physical, spiritual and mental well-being."