Beaumaris (beautiful marsh). Although planned from the start, building work only began after the Madoc ap Llywelyn's rebellion in 1294. The castle was never finished, maybe due to lack of funds. Or maybe the building was too heavy to sit on waterlogged ground.

Chepstow - earliest stone built castle in Wales one of the earliest in Britain.

Did you know that Wales has more castles per square mile than any other country