Dolbadarn Castle

A squat red-stone tower rises abruptly from the valley floor between Llanberis and Caernarfon, impossible to miss as you drive through Snowdonia. This is Dolbadarn Castle, and it's one of those places that rewards the short detour far more than you'd expect.

The castle itself dates back to the 13th century, when it served as a stronghold for the princes of Gwynedd. Today you're looking at the remains of what was once a formidable fortress - mainly the circular keep, which still commands the landscape in that satisfying way old fortifications do. There's no visitor centre or refreshment hut, just the ruin itself standing in a field with the mountains looming behind it.

Walking up to it takes perhaps fifteen minutes from the car park, and the views from the top (if you're fit enough to scramble up) are genuinely excellent. You get proper vistas across to Snowdon and down the Pass of Llanberis. It's the sort of place that works brilliantly if you're based at one of the local parks - Llanberis Touring Park or Glamping in Llanberis are practically on your doorstep, and it makes an easy morning's work before lunch.

History buffs will appreciate the medieval significance, and children do enjoy clambering around ruins, though there's not much to occupy them for more than an hour. Admission appears to be free, and it's accessible year-round. Worth stopping for if you're in the area, but don't expect crowds or facilities.