The British writer Caitlin Moran once wrote fondly of Aberystwyth's "Glitter-glue sea and smashed-cake castle," and these crumbling ruins at the southern end of the bay do have an endearing quality. Built in 1277, the castle was one of the key strongholds captured in the early 15th century by Owain Glyndwr, a Welsh prince who led the country's last serious bid for independence from England. Today it's a romantic, windswept ruin, rather incongruously used as a cut-through walking path by locals for whom it's nothing out of the ordinary at all. To find the ruins, just walk along the bay, away from the town center; they are located just after the small pier.
New Promenade, Aberystwyth, SY23 1JT, Wales