Photograph by Dave Newbould

Beaumaris Castle is the great unfinished masterpiece. Started in 1296, it was the last of the massive Edwardian fortresses of the 13th century to be built in North Wales, but money ran out before the fortifications reached their fall height. Beaumaris is nonetheless an awesome sight, regarded by many as the finest of Edward's Welsh castles. The king's military architect, the brilliant James of St George, brought all last experience and inspiration to bear when building this moated castle on the beau marais (beautiful marsh) overlooking the Menai Strait. In pure architectural terms Beaumaris, the most technically perfect castle in Britain, has few equals. Its ingenious - and perfectly symmetrical walls within walls design was state of the art for the late 13th century. Built into its plan were no less than four successive lines of fortifications and 14 separate major obstacles that any attacker would have to overcome, together with hundreds of cleverly sited arrow slits and the deadly "murder holes" to defend entrances. This outstanding fortress is a World Heritage listed site.