Craignethan Castle

The ruins of Craignethan sit on a dramatic bend of the Nethan Water, about three miles south of Lanark. It's a proper fortress - squat, serious, built to mean business rather than impress visitors. What you see today is mostly 16th-century work, though the bones of it go back further, and honestly it's the setting that does most of the talking here.

You can walk right up to it. The castle spreads across a rocky outcrop with thick defensive walls and what remains of a gun emplacement - that sunken artillery chamber is genuinely clever engineering for its time. Inside you wander through roofless chambers and scramble up spiral stairs that lead nowhere particularly dramatic, but the views down to the river valley compensate. It's not Instagram-ready, which actually makes it better.

History buffs will appreciate the defensiveness of the design - this was built when keeping the English out mattered. Walkers gravitate here naturally, especially if combining it with the riverside paths along the Nethan. Families with young kids might find it a touch underwhelming for more than an hour unless they're genuinely into ruins and clambering about. There's no visitor centre or tea room, so bring water.

If you're based at Ecosse Glamping nearby, it's a straightforward morning outing. Free to visit, open access, best in dry weather when the paths aren't treacherous. It's a working castle ruin rather than a polished attraction - exactly what some people want.