3.-Who built them?

Cardiff Castle- The castle was built by the Romans.
Raglan Castle- The castle was built by William ap Thomas.
Caerphilly Castle- The castle was built by Gilbert de Clare.
Chepstow Castle- It was built by wiliam the Conqueror or his son Roger Fitz Osbern on a high cliff overlooking the river wye.
Castle Coch- The castle was built by John Crichton-Stuart and William Burges.