Cainhoe Castle

Cainhoe Castle sits just outside Henlow as a proper oddity - a Norman motte-and-bailey that's been quietly crumbling for about nine centuries. You're basically looking at earthworks now, which sounds dull until you actually stand there and realise you're on a 900-year-old fortification.

The site itself is accessible but underwhelming if you're expecting stone towers. What you get instead is a raised mound with traces of the outer defences still visible if you know what to look for. It's the sort of place where history enthusiasts will spend twenty minutes poking around and taking photos, while others might manage five. Kids might enjoy scrambling up the bank, though there's not much to actually do once they reach the top.

Free to visit and no time limit - just turn up. The nearest proper facilities are back in Henlow, so you're not doing this as a destination on its own. Instead, combine it with a stay at Henlow Bridge Lakes, which is only a couple of miles away and breaks up a walking route nicely. The lakes park itself is decent enough - bit more substantial than a castle mound, at least.

Best visited on foot if you're staying locally, ideally as part of a longer country walk rather than a dedicated trip. Weather matters here; muddy and uninspiring in winter, at least pleasant to stand on in summer. Worth fifteen minutes if you're passing through Hertfordshire, not worth detouring for.