I recognize that my creation is not, strictly speaking, a full castle. However, I believe it meets the spirit of the challenge because it's supposed to be a ruin deep in the woods that the men of the forest have reoccupied.
Here are the pictures (note that the pictures are links):




I tried to make the edges of the cave "rough" to demonstrate that it's a cutaway from the mountain.

Here is a link to the Entire Gallery.
For those of you who would prefer Flikr, here's a link.