The beautiful structure of Caerphilly Castle, in South Wales. The leaning south east tower is on prominent display from this angle. Built by Gilbert de Clare in the thirteenth century, it is the second largest castle in Britain and supposedly helped introduce concentric castle defences (multiple curtain walls) to Britain. It’s a lovely castle with nice grounds and a nice village just outside its entrance. It is an accessible day trip from Cardiff.

http://cadw.gov.wales/daysout/caerphilly-castle/?lang=en
https://en.wikipedia.org/wiki/Caerphilly_Castle
https://en.wikipedia.org/wiki/Caerphilly