Altdahn
The two right photos shows how the castle was built on sandstone ledges that actually overhang.  It's a very precarious arrangement to say the least!
Below, some of the defensive works were carved directly from the rock.  Not only did this reduce construction time but it also created a better structure defensively.
To the right, one of the fireplaces showing original decorative molding around the hearth.
Left, an example of how the castle is built into the living rock.  The stone enhanced the defensive nature of the structure and made it less costly to build.