Königstein Fortress, one of Europe’s largest hilltop fortresses, offers stunning views over the Elbe Valley. Notable highlights include the Giant Cask, once the largest wine barrel in Europe, capable of holding 55,000 gallons, though it was never fully used. The fortress also played a role in history as a prison, famously holding American officers captured during World War II. Of course the boys are annoyed it is “just another castle”.