Grimsbury Castle - Main fortifications

The earthworks here are proper modest compared to what you might expect from a castle - no stone keeps or dramatic walls, just a series of grassy humps and ditches that take a bit of imagination to read. But that's actually what makes Grimsbury interesting. These are the remains of an Iron Age fort that later became a Norman stronghold, and once you clock what you're looking at, you can trace the defensive lines quite clearly across the field.

It's a ten-minute walk from Thatcham, so worth bundling into a wider afternoon if you're staying at one of the local caravan parks like Rhodeside Club nearby. History enthusiasts will find it genuinely compelling - the kind of place where you start photographing the contours and working out sight lines. Families with younger kids might struggle; there's no visitor centre, no interpretation boards, and the appeal is entirely cerebral. Older walkers and archaeology buffs will get hours out of it though.

The site sits in open countryside, so bring a map and go when the ground's dry if possible - wet grass makes the earthworks harder to distinguish. Free to visit, naturally, and you can poke around at your own pace. If you're combining it with Cherry Bird Country Park three miles away or Bishops Green Farm a bit further out, you've got a decent little historical trail going. Worth the detour if you're into this sort of thing; skip it if you need visible battlements and gift shops.