I see a generic dark castle.

To me the tone gives a real haunted vibe and there are points that would seem to go well with a spacious scenery (rickety land bridge over a bottomless ravine?). A great addition to any horror genre type cartoon.

Heh

I like this,
I really like the creepy melody on the top end. Wasn't too crazy about the drums, but I think the melody sets the tone and surprisingly makes this song. If you expounded, you could probably use that as a motif to make reoccurring theme based movie scores :D

One idea that could work as well is adding a swelling drone at the end.

Overall,
Great work!