The reserve consists of three wildflower meadows and a large area of woodland. The reserve lies on the site of a former coal-mine and is a wonderful example of how nature can reclaim an area.
Allt Rhongyr is within the Brecon Beacons National Park, adjacent to Craig y Rhiwarth Nature Reserve and offers dramatic views of the Tawe Valley. It features a diverse mix of limestone grassland, acidic grassland and woodland and it was once the site of an iron age hillfort. The site is now managed by grazing under an agri-environment scheme.
This reserve is a good example of a traditional wildflower meadow, a rare habitat in these days of intensively managed farmland where large quantities of both fertiliser and grazing animals are applied to meadows that may have once looked like this, but are now bright green with very few plant species surviving.