Mynydd Bychan, Mound

The mound at Mynydd Bychan rises from the Powys landscape like something left behind from another world - and technically, it was. This is an Iron Age hill fort, though what you're looking at now is earthwork archaeology rather than stones and ramparts. The site itself is basically a raised fortification surrounded by ditches, best appreciated if you're willing to walk the perimeter and actually visualise how people defended this place two thousand years ago.

It's a proper trek to get any real sense of it. The mound dominates the immediate area, but you won't find interpretation boards or facilities - this is archaeology in the raw. Walkers will find it worthwhile, particularly those interested in Iron Age settlement patterns across the Welsh borderlands. Families with young kids might find it a bit abstract unless they're the type to enjoy scrambling about on earthworks and imagining Celtic warriors. Allow an hour to properly explore the site and the views across towards Hereford.

There's no charge and no set opening hours - it's accessible year-round, though winter rain can turn the ground boggy. Summer's the sensible time to visit. The site sits within easy reach of several campsites clustered around the Olchon Valley and Hay-on-Wye area - Olchon Valley Campsite is barely five miles away. Pair it with a walk in the Black Mountains or a visit to Hay-on-Wye's bookshops and you've got yourself a proper border country weekend.