Kilmartin Castle

The castle sits low and deliberate on the landscape near Lochgilphead, a fortress that's seen proper centuries unfold around it. What you're looking at is a 15th-century stronghold - solid stone, no nonsense about it - that belonged to the Campbells and tells a fairly brutal chapter of Scottish clan politics. The structure itself is compact rather than sprawling, which means you can walk round it reasonably quickly, though there's genuine atmosphere in the thick walls and the way it commands the valley.

This one works best for history enthusiasts rather than kids seeking dramatic towers and dungeons. It's not a theme park version of a castle - it's the real thing, weathered and honest. If you're already exploring Argyll's archaeological riches, Kilmartin Castle slots in as part of a proper deep dive into the region's medieval past. The nearby Pod Over By holiday park is just four miles away, so you could base yourself there and take it as part of a walking circuit through Argyll's castles and standing stones.

Access and opening details aren't entirely straightforward to pin down - you'll want to check locally before you go, as visiting arrangements can be limited. Even if you can't get inside, the external stonework and setting are worth the detour if you're in the area. Lochgilphead makes a sensible jumping-off point for the surrounding countryside.