In the original mine craft (no mods) this will not move around but it can be placed in the sky using MC_edit.
I currently do not have any information about airship game mods, although i have seen a few on youtube, that would be a good place to start.
Lovely castle, I can't wait to finish building it :)
I do have one question: When I import the .schematic file in Schematic2Blueprint, the program says that there are unrecognised bricks used in the castle. Any idea what they are?