Kinda liked Caerphily cos it was just over the hill from me at uni.
The tower leans more than the leaning tower of Pisa.
Cardiff Castle and the little folly castle of Castell Coch (just north of Cardiff) were regular haunts during my time at uni too.
Also, it should be a requirement of this thread to post a pic of the castle in question.
Here’s Castell Coch, also known as the Fairytale Castle for obvious reasons. There was good MTBing in thewoods around there, really quite steep in places!