National Trust - Dinefwr

The ruins of Dinefwr Castle sit on a hilltop overlooking the Towy Valley, and the walk up alone is reason enough to make the trip from Llandeilo. This is proper medieval Wales - stone walls, sweeping views, and a sense that you're standing somewhere that actually mattered in history. The National Trust manages the grounds, which means they're well kept without feeling sanitised.

What you get is a castle keep and outer walls to explore, plus the surrounding parkland that's been here since the 18th century. There's a decent circular walk that takes in both the castle and the landscape, and on a clear day you can see for miles across rolling farmland. Kids will find it interesting for an hour or so, though don't expect interactive exhibits - this is old stones and views, not a theme park. History types will want longer, especially if they read up on the Dinefwr lords beforehand.

It's free to wander the grounds, which is excellent value. Allow a couple of hours if you're doing the full walk and poking about the ruins. The best time is late afternoon when the light hits the valley properly and you've got fewer people around.

Being so close to Llandeilo makes this a natural add-on to a park holiday in the area. Ravenscroft Retreats is barely a mile away, making it handy for a morning ramble before heading elsewhere. Combine it with a stroll round the town itself for a proper day out.