The Castle of Dürnstein in Austria. In 1192 Richard the Lionheart was imprisoned in this castle while returning from the Third Crusade. He was later passed over to Henry VI, the Holy Roman Emperor, who locked him in the Trifels Castle (present Germany). I visited Trifels a couple of years ago but wasn't really photographing then... Anyways, i hope you like the above photo:) Thanks to Bernhard for pointing me to this location!
Update: Yes, the sky is real, it is not photoshopped into the picture. Single long exposure, wide angle lens, dark gray filter.