United Kingdom
A childhood favourite, Carreg Cennen Castle is unique in Wales as it is the only castle built by the Welsh, for the Welsh. The other castles you are likely to recognise and visit west of the border were instruments of subjugation, used by English (or, more accurately, Norman) rulers to keep the Welsh under control.
Carreg Cennen is all the more interesting because of its isolation and spectacular location, perched on a ridge in the remote west of the Brecon Beacons national park, its romantic setting has inspired generations of artists, including Turner.
Approached through a farmyard, you will need decent shoes for the steep path and, unusually, a torch. The latter is necessary to follow the tunnel which starts within the castle walls and descends deep into the cold, wet rock below - a spooky climax to the visit for children and grown-ups, where it is believed prisoners were held captive for months on end in the pitch black.
Once you step, blinking, back into the daylight, the downhill trek will return you to the farm and car park where lunch, snacks and cream teas can be bought.
Nearest village is Trapp. Nearest station is Ffairfach on the Swansea - Shrewsbury line. Llandeilo, Carmarthen and Swansea are all 20-45 minutes away.
01558 822291, carregcennencastle.com
Adults £3.70, children 5-16 £3.30
Google map: tinyurl.com/3yznou3