Craig y Cilau National Nature Reserve

The limestone cliffs rise up properly dramatic from the valley floor near Crickhowell, and that's what Craig y Cilau is - a wild, windswept nature reserve that feels like it belongs more to the peaks than to the gentle Mid Wales landscape around it. You're walking through beech woodland that clings to steep slopes, then suddenly you're among exposed rock faces and open grassland where the views stretch for miles across Powys.

It's a proper walker's destination, not a stroll. The terrain is unforgiving and the paths can be muddy even when it hasn't rained, so decent boots matter. Allow at least two hours if you want to reach the top, longer if you're taking it slow. The limestone geology means you'll spot rare plants and cave systems - it's designated as a Site of Special Scientific Interest, which explains why the access is a bit limited compared to the usual National Trust honeypots.

Historically significant too. This area was mined for limestone centuries back, and you can still see evidence of that industry dotted about. Bats use the caves, which makes it particularly valuable for conservation work.

Families with young kids might find it frustrating - the steep sections aren't suitable for pushchairs and the scrambling bits feel exposed. Serious walkers and geology enthusiasts will get far more from it. It's free to visit and worth combining with a stay at Cwmdu Campsite just down the road, which gives you a proper base for exploring the wider Crickhowell area. Go early in the day to avoid the afternoon crowds, and bring a map - the waymarking isn't as clear as it could be.