Drumena Cashel

You're standing in a field outside Castlewellan looking at what amounts to a ring fort - a circular earthwork with a stone-built cashel (defensive wall) at its core. Drumena Cashel is genuinely old, dating back to around the 7th century, and the souterrain underneath is the real draw here. These underground passages were storage chambers or refuges, depending on who you ask and which historian you trust.

The site itself is modest. You won't find visitor facilities or interpretation boards spelling everything out - this is archaeology in the raw. The earthen rampart is still visible, and if you're keen on early medieval settlement patterns, there's proper substance here. For most people though, it's a 20-minute wander at best, then you're done. Kids under ten will lose interest fast unless they're already fascinated by Iron Age life.

It's free and open access, which is the way these things should be. Allow an hour if you're stopping in Castlewellan anyway - the town itself is pleasant enough for a coffee. If you're based at one of the nearby campsites - Tollymore Campsite is closest at 2.2 miles, or the posh option at Enniskeen Estate a bit further - Drumena makes sense as a half-hour detour before tackling Tollymore Forest Park proper, which is the real heavyweight in the area. Don't plan a trip around it alone, but it's worth knowing about if you're already exploring the Mourne foothills.