Some info:
-I think the Rondo of Blood Dracula stage3' thing is made simpler in The DraculaX Chronicles, where the silhouette is even easier to identify.
-Carmilla's Castle in Circle of the Moon is not in Romania, but in Austria, I believe, and he resides there for a while.
-Dracula exists in The Castle Proserpina with Elizabeth in England.
-Also, the other examples people mentioned.
-In Lords of Shadow's epilogue, he's residing in an abandoned church somewhere in a city. That's most likely not his castle.
So it's safe to say that he can leave the castle.
This also matches the stories in Bram Stoker's Dracula, both book and movie.
It's possible that his power is weaker outside of the castle but 'citation needed'.
Maybe as long as he's got 'earth from his property' it'll work just fine, like in Bram Stoker's novel?