Burwell

The earthworks at Burwell are what archaeologists get genuinely excited about - a rare Iron Age fort that's managed to survive in reasonable nick despite being in the middle of Lincolnshire farmland. You're looking at defensive ditches and banks that would have been properly imposing two thousand years ago, though these days they're more subtle than dramatic. The site itself is free to wander, which is the good news. The less good news is that unless you're genuinely into Iron Age settlement patterns, thirty minutes probably does it. There's no visitor centre, no interpretation boards worth mentioning, just the earthworks and your imagination.

It's worth the detour if you're already exploring the area around Horncastle - a cracking market town about four miles south - but I wouldn't plan a trip solely around Burwell. History enthusiasts and serious walkers will get more from it than families with restless kids. Go in late afternoon when the light's better for photography and the fields are quieter. If you're staying at one of the nearby parks - Lincolnshire Glamping sits just 2.4 miles away, or Oxcombe Campsite at 3.1 miles - it makes sense as a twenty-minute drive to stretch your legs and poke around something genuinely old. Combine it with a walk around Horncastle's Georgian streets and a decent pub lunch, and you've got a proper morning sorted.