Caerphilly Castle
In the town centre, Caerphilly, South Wales Location map link for Caerphilly Castle
Caerphilly Castle is one of the great medieval castles of western Europe. Several factors give it this pre-eminence - its immense size (1.2h), making it the largest in Britain after Windsor, its large-scale use of water for defence and the fact that it is the first truly concentric castle in Britain. Of the time of its building in the late 13th century, it was a revolutionary masterpiece of military planning
One of Henry III's most powerful and ambitious barons, Gilbert de Clare, lord of Glamorgan, built this castle. His purpose was to secure the area and prevent lowland south Wales from falling into the hands of the Welsh leader Llywelyn the Last, who controlled most of mid and north Wales. De Clare built other castles on the northern fringes of his territory for the same purpose, such as Castell Coch. He had seized the upland district of Senghenydd, in which Caerphilly lies, from the Welsh in 1266 to act as a buffer against Llywelyn's southward ambitions. Llywelyn realised the threat and tried but failed to prevent the castle from being built; it was begun on 11 April 1268, was attacked by Llywelyn in 1270, and was begun again in 1271. This time it was completed without hindrance. Its message was not lost on Llywelyn, who retreated northwards. Apart from the remodelling of the great hall and other domestic works in 1322-6 for Hugh le Despenser, no more alterations were carried out, making it a very pure example of late 13th-century military architecture.
Below: southern view of the castle showing Caerphilly's postern gate (center) and the leaning south-east tower (right).
Caerphilly is unusual in being a late castle built on a virgin site. This allowed a unity of conception rare in medieval castles. It is a double-skinned parallelogram surrounded by large-scale water defences. The concentric arrangement was more flexible than earlier plans. It gave rapid access to any part of the castle by mural passages and wall-walks, towers and gatehouses could be independently held, attackers could be well covered and there was no possibility of mounting siege engines against the inner walls. The castle’s cellular structure and strength is indicated by the presence of numerous portcullises.
Below: general view of Caerphilly's inner ward showing the inner west gatehouse (left) and the north-west tower (right).
The outer skin or ward is formed by a low battlemented curtain wall with large semi-circular projections in the corners and gatehouses in the middle of the east and west sides. Only a narrow strip separates this from the much stronger inner ward which has high curtain walls, circular corner towers and two large strong gatehouses corresponding with the outer ones. The great east gatehouse is the highest part of the castle and was its nucleus. As will be seen, it could be separately defended if necessary.
The south and north lakes around the castle formed an almost insuperable barrier to attackers. The dams themselves are a major achievement of medieval engineering. The southern, earliest one is a massive earth platform revetted in stone and strengthened on its lower side by eight great buttresses (below left). To the right of the entrance to the castle is the northern dam, a narrower platform with a high outer wall with three great towers (below right) which are now unfortunately suffering from subsidence on the marshy ground. At its end is a strong postern gate and drawbridge. Outside the dam is a moat fed by sluices in the southern dam.
 
 
View of the southern dam at Caerphilly.
 

View of the three great towers along the northern dam.
 

The outer defences were completed by making a 1.2h artificial island to the west of the castle, known as the hornwork. A trench had already been dug in the early stages of construction outside the west side of the castle; now another was dug further west and the area between was raised, levelled and revetted in stone to form the hornwork. The north-west side has two semi-circular projections covering the drawbridge, the ruins of which can be seen between them.
Right: the outer east gatehouse at Caerphilly, the main entrance to the castle.
The outer gatehouse on the east side (right) is both the present and the original entrance. Here the main characteristics of the castle as deterrent become apparent - its great strength, its severity, its lack of windows and lack of decoration. Inside the gatehouse is an exhibition about the castle, and stairs lead up to roof level, from which is a panoramic view. Crossed rather than plain arrowslits in this gatehouse and in other buildings on the dams show that they are slightly later than the main castle. To the left is the platform of the south dam, the wider northern end of which may ...