David Newnham breaches its defences
Everybody loves a good castle. Unfortunately, in these largely untroubled islands, good castles are few and far between.
On the one hand, there is your romantic ruin. Here, everything is left to the imagination - floors, roofs and those all-important battlements having long since fallen prey to the British weather and thieving locals in need of decent building materials. Then there are your Windsors, kept intact by continuous occupation but invariably messed about to such an extent that they are now little more than stately homes with turrets.
Only occasionally can we experience the best of both worlds - a castle that has portcullises and spiral stairs and a moat full of water, and still breathes the fiery breath of a working medieval fortress. A good proportion of these are found in north Wales, where Edward I built a chain of many-towered strongholds to break the power of the Welsh princes.
But it is a small town in south Wales, just over the hills above Cardiff, that boasts the grandaddy of them all. Built by the English baron Gilbert de Clare between 1243 and 1295, Caerphilly Castle is a truly astonishing structure. A Welsh poet in the 14th century called it "giant Caerfilli", and 500 years later, Alfred Lord Tennyson described it as not so much a ruined castle as a ruined town. When Tennyson visited, the castle was indeed in a ruinous state, scoring full marks for romantic appeal but offering little in the way of walk-through experience.
But all that was about to change. By the end of the 19th century, Cardiff was the world's busiest coal port, and the lion's share of the profits was going to the third Marquess of Bute, John Patrick Crichton Stuart, whose father had founded the docks and developed the Rhondda coalfield. A passionate medievalist, he was one of the world's richest men, which meant he had one or two real castles to play with.
At Cardiff and, with more artistic success, at nearby Castell Coch, he had his architect, William Burges, convert existing ruins into enchanting fantasy castles. But at Caerphilly, he took an altogether more serious approach, recording the remains with archeological fervour and preventing further decay.
Then in the 1930s, his son, the fourth Marquess, John Crichton Stuart, went one step further, and began painstakingly reassembling fallen masonry, restoring roofs and battlements and demolishing houses that had been built hard against the castle walls.
While such meddling with the fabric of history is out of line with modern thinking, it does mean that visitors to Caerphilly can experience the castle in a way that is seldom possible. Which is particularly fortunate, as this is without doubt one of the most exciting castles in western Europe. Head custodian Tony Payne is in no doubt that the monument's unique selling point is its sheer size. "It's awesome," he says. "I live up on the hillside and I often look down and think what a huge statement it is. 'This is what we can do,' it says. 'This is what we're up to'."
What de Clare was "up to" was securing a large section of south-east Wales for himself, in the face of armed opposition from Llywelyn ap Gruffudd. To this end, he fortified no less than 30 acres of land, which makes Caerphilly the second most expansive castle in the UK, the largest being Windsor.
But there is more to Caerphilly than bulk. Having taken part in the siege of Kenilworth and seen at first hand the effectiveness of water as a defence, de Clare girded his stronghold with two artificial lakes, holding them in check with a pair of massive fortified dams. Not only did the lakes keep besieging forces with their boulder-slinging engines at a safe distance, but it also made undermining the walls impossible. Only by crossing a succession of drawbridges could an enemy hope to gain access to the main fortress. And that was when the castle's ground-breaking design would have made the going tougher than ever.
By donning headphones and following a 45-minute audio tour, you can now see this castle's ingenious defences through the eyes of an assailant and understand why, in the words of Mr Payne, "it was once besieged by 10,000 Welshmen, and a handful of Normans inside were able to stop them getting in".
For Caerphilly was the first castle in Britain to be built from scratch on the principle of concentric rings, forcing an attacker to fight through a succession of barriers while under constant fire from the loftiest, innermost towers. A fiendish array of hinged bridges, angled arrow slits and overhead "murder holes" made forward progress virtually impossible, while defenders were free to move about the castle at will, concentrating their efforts where they were most needed. Thanks to the relative completeness of these sophisticated defences, it's easy for visitors to grasp the mechanics of siege warfare.
On one section of the battlements, a projecting timber fighting deck has been reconstructed to show how a handful of crossbowmen could pick off anyone approaching the walls, and the castle is the proud possessor of four replica siege engines in full working order.
Surprisingly, given that this was primarily a military installation, a tour of Caerphilly offers insights into less belligerent aspects of medieval life. Thanks to the coal barons and their almost limitless wealth, the cavernous great hall has a timber roof and replica minstrel's gallery, giving a glimpse of the magnificent lifestyle their medieval forebears enjoyed. There are even the recognisable remains of a corn mill within the walls, bearing out Tennyson's assertion that this was more town than castle. Powered by a constant stream of water from the lake, and protected by its own tower, this would have ensured that the defenders could enjoy fresh bread even during a siege.
Today, displays and videos in the towers explain every aspect of the castle's existence, from politics to geology to a medieval soldier's daily pay (a duke got the equivalent of 66p, a knight 10p and a footsoldier 1p).
But, ultimately, it is the size and strength of the structure that impresses. For everyone loves a good castle, and Caerphilly ranks among the very best.
WORTH THE VIEW
Guided tours are available by arrangement (tel: 02920 883143), and medieval costumes can be supplied. Teachers who prepare a school visit in advance are allowed free admission. The castle is in the care of Cadw, the Welsh Assembly's historic environment agency: www.cadw.wales.gov.uk.
Don't miss: The leaning tower.
Probably owing to subsidence, this three-storey structure has split and now tilts at an angle of 10 degrees from the vertical - more than the campanile at Pisa. Never fully restored, it retains more genuinely original features than other parts of the castle.
Siege engines: A trebuchet, magonel, ballista and perrier, these monsters are in full working condition. Three times a year, they demonstrate their power by hurling huge concrete boulders into the water.
Civil War redoubt: This tree-covered gun platform was constructed in the 17th century next to one of the lakes. Excavations in the 1960s also revealed remains of a Roman fort.
By car: From the M4 motorway, exit at junction 32, then take the A470 or A469 and follow the signs for Caerphilly.
By rail:Take the train to Cardiff, then catch a Valleys Line service to Caerphilly.
Opening: April 1-May 31, 9.30am-5pm daily. June 1-September 30, 9.30am-6pm daily. October 1-31, 9.30am-5pm daily. November 1-March 31, 9.30am-4pm, Monday-Saturday, 11am-4pm, Sundays. Last admission 30 minutes before closing. www.caerphillycastle.org
Price: Adults pound;3, family ticket (two adults and up to three children under 16) pound;8.50, concs pound;2.50, children under five free. Audio guide pound;1. Children under 12 must be accompanied by an adult. No dogs except guide dogs.
Facilities: Parking, toilets, gift shop.
Attractions: Special events take place at the castle throughout the year, from drama productions to displays of jousting and archery. August 29 and 30, noon-4pm, siege engine firings in castle grounds (normal admission charges). See website for details and future events.
Anywhere else like it?
* Castell Coch, the 13th-century ruin converted into a romantic folly by the third Marquess of Bute, lies a few miles north of Cardiff. Like Cardiff Castle, it is open to the public.
* The chain of powerful castles Edward I built in north Wales used many of the ideas developed at Caerphilly. Notable examples include Harlech, Caernarfon, Conwy and the ultimate concentric castle, the almost perfectly symmetrical Beaumaris on the island of Anglesey. For information about all Welsh castles, including profiles, photographs and historical essays, see www.castlewales.comhome.html
* One of the most powerful fortifications in England, the water defences of which probably inspired those at Caerphilly, is Kenilworth in Warwickshire.
* The first British castle to use the concentric design was Dover, although here the plan evolved gradually. In Scotland, castles developed along different lines, in response to local conditions and largely under French influence.
* A comprehensive guide to castles in Britain is at www.castlexplorer.co.uk