Greenan Castle

A crumbling sandstone ruin perched on a rocky outcrop above Doon Valley - that's Greenan Castle, and it's considerably more dramatic than most Scottish castle remnants you'll stumble across. The structure dates back to the 15th century, though what you're looking at now is largely 18th-century work built atop medieval foundations. The whole thing leans slightly, which adds to its slightly precarious charm.

You can walk right up to it. The approach isn't exactly strenuous - a path leads from the nearby layby up to the castle's base, and you'll get proper views across the valley on the way. The interior is accessible if you're careful, though there's not much to see beyond the bare stone walls and the view out towards the Firth of Clyde on a clear day. Budget twenty minutes, maybe thirty if you're photographing or want to sit with a thermos and actually take in the landscape.

History types will appreciate the connection to Robert Burns, who spent time nearby. Walkers treating it as a pit-stop between longer rambles won't feel cheated. Young children might lose interest quickly once they've clambered about the ruins - it's not a place with interactive elements or much to do beyond looking.

If you're staying at Haven Craig Tara just down the road, Greenan makes a sensible afternoon diversion. Admission is free, and there's basic parking at the layby. Go when the light's decent - overcast days flatten the whole thing considerably.