Beaumaris, begun in 1295, was the last and largest of the castles to be built by King Edward I in Wales. Raised on an entirely new site, without earlier buildings to fetter its designer’s creative genius, it is possibly the most sophisticated example of medieval military architecture in Britain.
This is undoubtedly the ultimate “concentric” castle, built with an almost geometric symmetry. Conceived as an integral whole, a high inner ring of defenses is surrounded by a lower outer circuit of walls, combining an almost unprecedented level of strength and firepower. Before the age of cannon, the attacker would surely have been faced with an impregnable fortress. Yet, ironically, the work of construction was never fully completed, and the castle saw little action apart from the Civil War in the 17th century.