Mile Castle 51

Walking the Hadrian's Wall path near Haltwhistle, you'll stumble across Mile Castle 51 - a proper Roman fortlet that's genuinely got your heart racing if you're into this stuff. It's one of the smaller forts along the wall, built around AD 122, and what remains is a square stone structure with walls you can still make out despite nearly two thousand years of weather battering.

The fort sits in a commanding position overlooking the Tyne Valley, and you can absolutely see why the Romans chose this spot. They'd have watched troop movements and monitored the frontier from here. There's not much left to physically explore - you're not walking through elaborate rooms or anything - but the setting itself tells the story. The surrounding landscape hasn't changed much since legionaries tramped these stones.

This is one for the committed history walker rather than casual strollers. Kids under ten will probably get bored within ten minutes unless they're already obsessed with Romans. Allow an hour if you're taking photographs and soaking in the views; twenty minutes if you're just ticking it off. It's free, naturally - it's a ruined fortlet on open moorland.

If you're based at Haltwhistle Camping and Caravanning Club Site, it's a straightforward walk from town. Combine it with other stretches of the wall nearby for a proper day out. The site's only six miles away, which makes it the ideal jumping-off point for exploring this section without driving between each ruin.