Caerphilly is a big castle, covering 30 acres complete with moat and buttressed wall. A botched effort at demolition during the Civil War can be sen in the wall of the Drum tower that leans by 12 feet from the perpendicular. Never the less it is a beautiful site today.
The Romans built a fort around AD 75, and 500 soldiers were stationed here for about 50 years. The site was then re-assessed by the Normans in the 11th century. To start with they were content for the Cearphilly Mountains to act as a natural barrier between the Welsh in the mountains and the Normans on the fertile plains
However in the 1260s, the last Welsh prince of Wales, Llywelyn ap Gruffudd,
controlled Breconshire and was likely to move further south. He
was opposed by the Norman lord, Gilbert de Clare, who moved north to attack
the Welsh in 1267. He captured the Welsh lord, Gruffudd ap Rhys, and in the
next year begin the construction of Caerphilly Castle as a defence.
No sooner had construction begun, than the Welsh attacked and burnt it in 1270. Negotiations by King Henry III, the
withdrawal of Llywelyn, and building of Caephilly in 1271. It is thought that building went on for another 50 years
Caerphilly was built to a concentric design with successive lines of defence
set one inside the other. The attacker first had to cross the moat, with a great
curtain wall and gatehouse. There was then an inner moat and gatehouses
for the second line of defence. Finally, the inner ward, a large quadrangle
surrounded by four curtain walls, with massive round towers at each
corner and yet more gatehouses. The gatehouses were each castles in their own right, and could be separately defended.
It was attacked again in 1316 by Llywelyn Bren, who lost his life at the hands on the English in 1318..
Land of Castles - Wales