Pen-y-gaer Roman Camp

The earthworks here are properly impressive if you know what you're looking at. Pen-y-gaer sits on a hilltop near Crickhowell with defensive ditches and ramparts that once formed a Roman auxiliary fort, and you can still trace the layout across the grass if you've got an ordnance survey map handy. It's not a visitor centre with information boards - this is the real thing, left to the elements, which some people love and others find a bit underwhelming without context.

You'll need decent walking boots and at least an hour to poke around properly. The views across the Brecon Beacons are cracking, and on a clear day you can see why the Romans chose this spot. It's free to visit and there's parking nearby, though the approach involves a fair bit of uphill trudging through fields.

History types and serious walkers will get the most from this. Families with young kids might find it a bit abstract - there's no fort to walk around, just bumps in the ground. That said, if you're camping at Cwmdu Campsite just down the road, it's a logical detour on a decent weather day. Pencelli Castle Caravan Park is also within striking distance if you're basing yourself in the area for a week.

Go midweek if possible. Weekends attract the rambler crowd, which is fine, but the solitude here really does help you imagine the garrison watching the valleys below.