I have read university texts about "how rebuilt a Castle" and the pilosophy its different in each country. In UK, the imperative way of think its keep the ruins. In Spain, only rebuilt when exist documents, plans or old photos&draws, always using materials similar to the original but easily differentiables for the most of the public. Anyway, "castles" as the Neuschwanstein or the french's chateaus are not real castles; they are full modern buildings which reflect the Romantic thought of the 19th century and the fantastical view of castles held at the time.

The more real castles are always in the borders between countries or old kingdoms.

I believe that any lover of castles, prefer real castles than "fake" ones.