I'm terribly sorry for not taking time to figure out how to make a decent blog post, but I just wanted to share my strange idea with you guys. Yes, I'm well aware that there is absolutely no way to predict what is going on in Kubo-sensei's head, but I'm going to bet that the location of the Quincy palace is... the Moon.
Yes, the moon. The idea first came to me when I've read somewhere (unfortunally, can't remember where) that Kubo said that the "villains' base" is "somewhere near yet in a place where noone is looking" or, you can say, right "under your nose" (actually, I forgot the correct version of this proverb). Unfortunally, I don't have much proof to support my moon-theory, but here is something:
1) Remember, Kubo doesn't like to draw detailed background? Yet we can clearly see the moon above the mysterious figure in chapter 480 "The Thousand Year Blood War", we can see it in the colour pages above Hueco Mundo in chapter 487 "Breath But Blind" and we can see Ryuken glaring at it in the chapter 537 "Everything But The Rain Op. 10". 2) Another "art hint" - look at the chapter 484 "The Buckbeard" where we see the "Quincy palace" for the first place. See that darkness above the temple? This really looks like Space, doesn't it? 3) If this is really true, than Ichigo's Zanpakutō name - Zangetsu, which means "Slaying moon" is somewhat symbolic, don't you agree?
In the end...
Thank you for reading my thoughts. I would like to know if there is someone else who thinks that way and, of course, hear your thoughts. Please, express them in the comment section. May the spirits be with you.