Our apartment was centrally located, which was the best part. It was nothing special but convenient. Russ rested a lot so I found myself touring the area alone. Cardiff is compact with 3 universities in the area so there were always lots of students around. The main shopping area had modern buildings like the John Lewis department storeroom the left and the new library to the right. I never did figure out what the needle and circle structure represented.
The most prominent piece of architecture in the city is the castle, centrally located. I didn't take the tour but rather walked outside the perimeter in the Bute Park grounds.