What if he were left-handed?

Often you'll find two sets of spirals, one for up, one for down and especially for use in case of an attack. Also, one might be disguised and for use in an emergency. Other than that, they are relatively easy to build and are the most efficient use of space for vertical circulation.

And sometimes very fancy sets of two, such as those at Chambord.

I'm surprised no one has mentioned Burg Eltz, near the Mosel river. It's spectacular from the outside, the definition of what a "castle" should look like.

I'd never define Linderhof as a castle. It's a very lovely palace. Not at all what you might expect to see manned by a Frenchman in a Monte Python movie.

This is great! I've started checking out each suggestion. We decided to rent a car so we are starting to plan a route partially based on the one or two castles we pick from your posts.

Which one is thought to be the model for Mary Shelley's Frankenstein?

A quick surf of the net tells me the model for the castle in Mary Shelley's Frankenstein is Castle Frankenstein near Darmstadt.

Here's a link that shows an image of Burg Eltz: http://www.burg-eltz.de/e_index.html.

We liked our time on the Mosel much more than on the Rhine.

Burg Eltz is wonderful, but its not in the Black Forest or Bavaria. That's why I didn't mention it.

Actually, in German,

Schloss = palace (Linderhof, Versailles, etc).

Burg = castle (Eltz, Wartburg, etc).