here. I am unsure if this papercraft is a real or fictional building. The official title of the model is "Schloß Rosenberg" but a quick Internet search of that name did not reveal any real life buildings that look remotely like the model. If you have more information about this building please let me know.
Other Papercraft Castles:
Miniature Fantasy Castle
Papercraft Castle Lantern
Modular Miniature Gaming Castle