Caerphilly Castle: Merlin and Dr. Who
The castle has long been synonymous with Caerphilly. It dominates the town.
Caerphilly Castle is also a great backdrop for TV and film. It secured a starring role recently in the popular BBC TV series Merlin.
Dr. Who's Tardis seems to have been caught in a timewarp and was observed on top of one of the turrets at Caerphilly castle when I last visited.