There should be a castle that generates only in extreme hills biomes. Of course, since it would be big, it should be even more rare to find than normal generated structures.
Castles have been suggested many times in greater detail than yours, such as here. There are also many mods for these. Please use the search button before posting, and provide more details in your future suggestions.
Castles have been suggested many times in greater detail than yours, such as here. There are also many mods for these. Please use the search button before posting, and provide more details in your future suggestions.
Locking.