So we have 1800's castleish? Okay...
Maybe something in Russia. I'm trying to think of a country that still had castles and royal families in 1800. The US had just had a revolution, Napoleon was terrorizing Europe, England was fighting hard to get rid of him.
Oh! Brain storm!
Plot Idea: A poorish noble family is trying to avoid the war and the persecution of the aristocracy in France. In order to avoid detection, they have escaped to a very old family home along the German (known as the Confederation of the Rhine)
See Map (and let me tell you that was a pain to find!
What do you think?