Dinas Castle

The ruins of Dinas Castle sit on a rocky outcrop above the Afon Rhondda valley, roughly three miles south of Crickhowell, and they're genuinely worth the scramble up. What you get is a jumble of stone walls from a 12th-century fortress - nothing you can walk inside, but enough to get a sense of the place and the strategic thinking behind it. From the top, the views across the Brecon Beacons are proper excellent, especially on a clear day when you can see right across the valley floor.

The castle itself is small. Walkers and history types will find it rewarding; families with young kids might find the twenty-minute climb a bit much for what amounts to a ten-minute exploration of rubble. It's free, obviously, and you can access it via a rough track from the nearby village of Dinas. There's no visitor centre, no interpretive boards, just you and the stones - which, depending on your mood, is either brilliant or a bit underwhelming.

If you're camping in the area - Cwmdu Campsite is just four miles away and excellent - Dinas Castle makes a decent morning walk before heading back for lunch. Combine it with a stroll down to the river or a visit to nearby Crickhowell itself, and you've got half a proper day mapped out. The Brecon Beacons aren't far either, so it fits well into a wider walking itinerary. Go in good weather; muddy days make that final push to the top unnecessarily treacherous.