Colachla, dun site

You'll need proper hill legs and a decent map for this one. Colachla is a dun - that's a prehistoric stone fort - sitting on a hillside near Tarbert in Argyll, and there's not much left of it, to be honest. What remains are low stone foundations, mostly grass-covered, that give you just enough sense of where the Iron Age inhabitants built their defences. The walk up takes maybe forty minutes depending on your fitness, and the real reward is the view across the loch rather than the archaeology itself.

This is squarely for history types and serious walkers, not casual tourists. Children might find it dull after ten minutes - there's no interpretation boards, no facilities, just open moorland and old stone. It's a challenge even to spot the site if you're not careful with directions. Free to visit, obviously, since there's no gate or warden.

If you're staying at The Gather holiday park six miles away, Colachla works as a morning walk before heading to more substantial attractions elsewhere in Argyll. It's the kind of place that rewards preparation - research beforehand, bring good boots, and go when the weather's decent. On a grey day it'll feel rather bleak. Worth the detour only if Iron Age forts genuinely interest you and you're already in the area.