Concentric defences could develop through additions to an older castle. At the Tower of London, Castle Rushen on the Isle of Man and Kidwelly in Carmarthenshire, an added outer curtain is the means of adopting the system. Caerphilly in Glamorgan takes the arrangement further with water available for wide moats and lakes. Its intricate entrance defences make water part of the comparison alongside the spacing of walls.
Notable Point · 2:47-3:20
Concentric additions and Caerphilly's water defences
Outer curtains could turn older castles into concentric defences, while Caerphilly used moats, lakes and elaborate entrances to develop the system further.