Queenborough Castle

What remains of Queenborough Castle today is honestly rather modest - a handful of low stone walls and earthwork lumps on the Isle of Sheppey, just outside Sheerness. Built in 1361 by Edward III as a military fortress to defend against French raids, it's now more of an archaeological site than a proper castle you can wander round. The original structure was substantial enough in its day, but time and the elements have done their work.

You'll spend maybe thirty minutes here, tops. There's no visitor centre, no interpretation boards, and precious little to actually see beyond the ground plan if you're not already interested in medieval fortifications. For archaeology types or serious military history enthusiasts, it's worth the detour - you can still make out the defensive layout and imagine the garrison at work. Kids will likely lose interest quickly unless they're genuinely gripped by castle sites.

The real appeal here is combining it with a broader Sheppey outing. Stay at Sheerness Holiday Park or Ashcroft Coast Holiday Park and make this part of a day exploring the island's coastline. The walk to the castle itself is pleasant enough, with decent views across the water. Check locally before you visit - access and opening arrangements can be vague for these small English Heritage sites. It's free, or at least, nobody seems to charge, but do ring ahead if you're making a special trip.