Caerphilly Castle

Gilbert de Clare began building in 1268 and produced the first fully concentric castle in Britain, surrounded not by a dry ditch but by artificial lakes held back by a dam over three hundred metres long which is itself fortified with towers and gates; the water defences cover about twelve hectares, making the site the second largest castle in Britain after Windsor. The southeast tower leans about ten degrees out of vertical, further than the tower at Pisa, the result of subsidence or of an attempt to demolish it by undermining, and it has stood at that angle for centuries. The great hall was refitted in the 1870s and 1930s by the Marquesses of Bute, who also restored the lakes, which had drained. Replica siege engines stand on the lawns.

What you actually see

• The leaning tower - about ten degrees off vertical, more than Pisa's.
• The water defences - artificial lakes across roughly twelve hectares.
• The fortified dam - a three-hundred-metre platform with its own towers.
• The restored great hall - refitted by the Bute family in the 1870s and 1930s.

When to go

April to October for full opening and the best of the lakes; winter hours are shorter. Still days give reflections of the whole castle in the water, which is the standard photograph.

Honest expectations

Most of the interior is empty stone with only the great hall furnished. The site is very large and exposed, with long walks around the water defences. Some towers are closed and the wall walks are limited.

Nearby

Cardiff lies south; the Rhymney valley runs north from the town.