1. This is a movie about Ludwig II of Bavaria. Even if you haven't heard of Ludwig, you've certainly been influenced by him: his castle Neuschwanstein provided the model for Walt Disney's Magic Kingdom and he was a patron of Richard Wagner. I had almost certainly heard of him before, but I was most recently interested in him because I played Gabriel Knight: The Beast Within, an FMV adventure game from Sierra.
2. Gabriel Knight is a series of supernatural mysteries. The first one has to do with voodoo and is...problematic, even though the game itself is solid. The Beast Within is less problematic, unless you regard gay-metaphor lycanthropy as problematic.
3. Ludwig is obliquely alluded to in The Waste Land:
Summer surprised us, coming over the Starnbergersee
With a shower of rain; we stopped in the colonnade,
And went on in sunlight, into the Hofgarten,
And drank coffee, and talked for an hour.
Lake Starnberg is the location where Ludwig died by drowning (possibly? suicide?)--the first of Eliot's deaths by water.
4. Ludwig was also gay--and this, too, ties into The Waste Land in some way that I've not totally unpacked. A few lines later and Eliot introduces hyacinths, named for the male lover of Apollo, and much later Mr. Eugenides will proposition a (male?) narrator with an offer of a weekend at the Metropole. Thus, Ludwig unites three factors (Wagner, drowning, and homosexuality) that are woven throughout Eliot's poem.
5. Visconti's previous movie was Death in Venice, which I've been meaning to watch but haven't quite yet. My understanding is that it also deals with homoerotic desire of some sort and also features a lead who visibly decays onscreen, as Ludwig does here.
6. At any rate, Visconti plays it slow with the revelation of Ludwig's sexual orientation, teasing us at first with the possibility of an unrequited romance with his cousin Elisabeth. However, she notes (with a nice, subtle bit of psychology) that what he really wants is an impossible love; the implication is that he is looking for a woman he can be in love with without needing to go beyond a chaste kiss. Finally, though, Ludwig makes a move on one of his servants and from then on there's no question from him or anyone else (in fact, once we know for certain that he is gay, it seems like everyone in the movie remembers that they always knew).
7. Eventually, Ludwig does try to marry but winds up cancelling and spending his time isolated in his castle[s] with a band of young, handsome male servants. Meanwhile, he slowly decays--his teeth go black, his hair goes wild--while everyone around him stays noticeably the same age (including his younger brother Otto, who never looks much older than nineteen). I could try to make something out of this, like an observation about how we never see people immediately around us getting older, but I think it's more likely that Visconti just didn't care about aging his cast.
8. This movie is long at almost exactly four hours. The Irishman is only 3 1/3. Like The Irishman, the time--once invested--does not seem wasted; the length lulls the viewer into this decadent story about a fairytale prince and his tragic end (does he commit suicide? Or is there something else going on?).
9. Wagner shows up, but he seems often more like a cunning fraud than a genius. I do feel a bit cheated on this score; Ludwig's reputation now rests almost entirely on his castles and his patronage of Wagner, and while neither of these are given a lot of attention, I do rather feel like we should be allowed to experience some of Wagner's genius instead of taking it for granted. Or maybe I just wanted to see some Wagner (I'm going to be watching some Wagner soonish).
10. Ludwig never attempts to solve the mystery of Ludwig's life. Was he mad? Was he a dreamer crushed by a cruel world? Was he a decadent aristocrat? All three? None of the above? You could make a case for each of these based on the evidence in the film. As Ludwig himself observes, he desires to be an enigma even to himself. Ludwig honors that wish.