One of the coolest moments in Rogue One: A Star Wars Story comes when we pay a visit to Darth Vader's castle on Mustafar, the fiery planet where Obi-Wan Kenobi managed to defeat him during the events of Revenge of the Sith. The movie never identifies it as that, but Lucasfilm's Pablo Hidalgo has confirmed that it is and that its inclusion in the Star Wars Rebels season one finale was deliberate.
However, Hidalgo's Star Wars: Rogue One: The Ultimate Visual Guide sheds even more light on the "Dark Monolith." In a fascinating twist, it's The Emperor who has seen to it that Vader is forced to live on the planet where he suffered his greatest failure. "Vader’s personal abode is an obsidian tower on an inhospitable world," he reveals. "It is the Emperor’s design that Vader lives in such an unforgiving environment. Vader’s attendant, Vanee, visits Vader as he meditates within a rejuvenation
chamber. The stark, modern structure is built over an ancient castle full of dark secrets."
Dark secrets? Well, in The Art of Rogue One, author Doug Chiang reveals that the castle was, "built over a natural cave — a Sith cave deep down below, in the lava world." He also indicates that this is somewhere we'll return to down the line, adding: "We were building worlds, so we always had to keep in mind the broad strokes and the big picture, in case they were needed for the story"
It would make a lot of sense for Kylo Ren to pay a visit here, especially as concept art for Star Wars: The Force Awakens included various designs for Vader's castles. What do you guys think of these details?