Dawn of Sorrow's Castle is not Dracula's at all; it belongs to Celia's Cultists.
It is unknown where its location is, exactly, but we see Windmills in the ending scene so... Holland?
Regardless, that particular castle features the iconic Staircase, as well as a hidden "Castle Entrance Hall" section deep underground.
So, to recap:
-some castles that are not Dracula's Castle may have the stairs/throne room.
-some castles ARE versions of Dracula's Castle, and yet don't have those stairs.