Audley's Castle (State Care Monument)

The ruins of Audley's Castle sit on a rise near Downpatrick, a handful of crumbling stone walls that don't look like much until you're actually standing among them. Built in the 15th century, it's a straightforward rectangular tower house - the kind of fortification Ulster landlords threw up to keep their estates secure. There's not a roof, barely intact windows, but the structure's solid enough that you can work out how people actually lived in these places.

It's free to visit and takes about twenty minutes to have a proper look around, though you could spend longer if you're the sort who photographs every bit of masonry. The site's unguarded and unstaffed, which means you turn up when you like, no gates to unlock. There's a modest layby nearby for parking. Bring a torch if you want to see into the lower rooms - they're dark enough that details are hard to spot in dull weather.

Walkers will get more from this than casual visitors. It's not a destination in itself, but it works well as a stop on a loop walk around the area. If you're already staying at one of the excellent caravan parks nearby - Castle Ward is just a mile away, or Delamont's five-star facilities are four miles off - it's absolutely worth the detour. History enthusiasts will appreciate the genuine early medieval Ulster feel of the place, though there's precious little interpretation on site. Families with young kids might find it a bit bare and forgettable after ten minutes.